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DRUG IMAGES
CVS HEARTBURN RELIEF CHEW TAB
The following indications for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide) have been approved by the FDA:
Indications:
Dyspepsia
Heartburn
Professional Synonyms:
Brash
Functional dyspepsia
Pyrosis
Indications:
Dyspepsia
Heartburn
Professional Synonyms:
Brash
Functional dyspepsia
Pyrosis
The following dosing information is available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide):
Antacids are administered orally. The dose of antacids should be expressed in terms of mEq of acid neutralizing capacity. Dose and frequency of administration depend on the acid secretory rate of the stomach, gastric emptying time, and the disorder being treated.
The duration of action of antacids is determined principally by gastric emptying time. In fasting subjects, antacids have a duration of action of 20-60 minutes. However, if the drugs are administered 1 hour after meals, acid neutralizing effects may persist up to 3 hours.
Sodium bicarbonate generally has a shorter duration of action than other antacids. Antacids should be used for longer than 2-week periods only under the management of a physician and as part of a carefully planned therapeutic regimen.
There is considerable variation in in vivo acid neutralizing capacity of equal volumes of different antacids and antacid products. Since suspensions are more rapidly and effectively solubilized than powders or tablets, antacid suspensions have a greater ability to react with and neutralize gastric acid. Antacid suspensions have a smaller particle size than do tablets and drying of antacid suspensions to prepare powders and tablets causes substantial loss of ability to neutralize acid.
In general, an antacid suspension is preferable to a tablet or powder; tablets should be reserved for chronic use in patients who refuse suspensions because they are inconvenient or unpalatable. Tablets should be thoroughly chewed before swallowing.
The US Food and Drug Administration (FDA) requires that antacids have a minimum in vitro acid neutralizing capacity of 5 mEq per dose and that antacid labeling contain the in vitro acid neutralizing capacity; however, this FDA in vitro test does not correlate with in vivo acid neutralizing capacity.
For peptic ulcer disease, dosages of antacids are empirical and various antacid dosages have been used. In patients with uncomplicated duodenal ulcers or gastric ulcers, an antacid is administered 1 and 3 hours postprandially and at bedtime. In patients with duodenal ulcers, antacids are usually given for 4-6 weeks, and in patients with gastric ulcers, antacids are administered until healing is complete.
If symptoms of duodenal ulcer recur, some clinicians recommend that antacids be administered 1 and 3 hours postprandially and at bedtime for 1 week and, if pain is relieved, less frequently for an additional 1-2 weeks; these patients should consult their physicians if pain worsens or is not relieved after the first week of therapy. Additional doses of antacids may be administered to relieve ulcer pain which occurs between regularly scheduled doses.
For the acute management of moderate or severe esophageal reflux, an antacid suspension is administered every hour; if symptoms persist, antacids may be given every 30 minutes. For long-term therapy of esophageal reflux, antacids are administered 1 and 3 hours postprandially and at bedtime and whenever symptoms recur.
In the management of GI bleeding and stress ulceration, antacids are usually administered every hour and, for GI bleeding, the antacid dosage should be titrated to maintain the nasogastric aspirate above pH 3.5. For severe symptoms, antacid suspensions may be diluted with water or milk and given by continuous intragastric infusion.
To reduce the risk of anesthesia-induced gastric acid aspiration, an antacid suspension has been given 30 minutes before anesthesia.
In conjunction with dietary phosphate restriction in the management of hyperphosphatemia, 30-40 mL of aluminum hydroxide or aluminum carbonate suspension is administered 3 or 4 times daily.
Dosage of cimetidine hydrochloride is expressed in terms of cimetidine.
The usual adult IM or IV dosage of cimetidine is 300 mg every 6-8 hours. If necessary, parenteral dosage may be increased by increasing the frequency of administration, but the manufacturer recommends that IM or intermittent IV dosage not exceed 2.4 g daily.
When feasible, IV dosage should be adjusted to maintain an intragastric pH of 5 or greater.
When cimetidine is administered by continuous IV infusion in adults, the drug usually is infused at a rate of 37.5 mg/hour, but the rate should be individualized according to patient requirements. For patients requiring more rapid increases in GI pH, an initial 150-mg IV loading dose may be required.
In one study in patients with pathologic hypersecretory conditions, the average dosage by continuous IV infusion required to maintain gastric acid secretion at 10 or less mEq/hour was 160 mg/hour, but individual requirements varied considerably, ranging from 40-600 mg/hour.
For the prevention of upper GI bleeding in critically ill patients, cimetidine usually is administered to adults by continuous IV infusion at a rate of 50 mg/hour for up to 7 days; the manufacturer states that the safety and efficacy of continuously infused cimetidine for more prolonged periods have not been established. The manufacturer also indicates that an initial loading dose is not required when the drug is administered prophylactically in such patients. However, some clinicians recommend initiating cimetidine therapy in critically ill patients with a 300-mg IV loading dose administered over 5-20 minutes, followed by a continuous IV infusion initiated at a rate of 37.5-50
mg/hour and titrated according to gastric pH (e.g., maintenance of a pH of at least 3.5-4) by additional 25-mg/hour increments, generally up to a maximum rate of 100 mg/hour. Intermittent IV doses of the drug appear to be less effective in preventing upper GI bleeding than continuous IV infusions.
In the treatment of upper GI bleeding+, peptic esophagitis+, and stress ulcers+, IV or oral dosage of 1-2 g daily, administered in 4 divided doses, has been used.
When the potential benefits are thought to outweigh the possible risks, a pediatric cimetidine dosage of 20-40 mg/kg daily in divided doses has been used in a limited number of children.
Accumulation of cimetidine may occur in patients with severe renal failure; therefore, the lowest effective dosage of the drug should be used. In patients with creatinine clearances of less than 30 mL/minute, the manufacturer recommends oral or IV cimetidine dosage of 300 mg every 12 hours. Dosage may be adjusted on the basis of gastric acid secretory response.
Dosage intervals may be cautiously decreased from every 12 hours to every 8 hours or less, if necessary. In patients with severe renal impairment, accumulation of the drug may occur and the longest dosage interval compatible with an adequate response should be used. For the prevention of upper GI bleeding in critically ill patients, the manufacturer states that patients with renal impairment (creatinine clearance less than 30 mL/minute) can receive one half of the usual cimetidine dosage.
When hepatic impairment is also present, further reduction in dosage may be necessary. Because hemodialysis greatly reduces blood cimetidine concentrations, cimetidine should be administered at the end of dialysis and every 12 hours during the interdialysis period.
The duration of action of antacids is determined principally by gastric emptying time. In fasting subjects, antacids have a duration of action of 20-60 minutes. However, if the drugs are administered 1 hour after meals, acid neutralizing effects may persist up to 3 hours.
Sodium bicarbonate generally has a shorter duration of action than other antacids. Antacids should be used for longer than 2-week periods only under the management of a physician and as part of a carefully planned therapeutic regimen.
There is considerable variation in in vivo acid neutralizing capacity of equal volumes of different antacids and antacid products. Since suspensions are more rapidly and effectively solubilized than powders or tablets, antacid suspensions have a greater ability to react with and neutralize gastric acid. Antacid suspensions have a smaller particle size than do tablets and drying of antacid suspensions to prepare powders and tablets causes substantial loss of ability to neutralize acid.
In general, an antacid suspension is preferable to a tablet or powder; tablets should be reserved for chronic use in patients who refuse suspensions because they are inconvenient or unpalatable. Tablets should be thoroughly chewed before swallowing.
The US Food and Drug Administration (FDA) requires that antacids have a minimum in vitro acid neutralizing capacity of 5 mEq per dose and that antacid labeling contain the in vitro acid neutralizing capacity; however, this FDA in vitro test does not correlate with in vivo acid neutralizing capacity.
For peptic ulcer disease, dosages of antacids are empirical and various antacid dosages have been used. In patients with uncomplicated duodenal ulcers or gastric ulcers, an antacid is administered 1 and 3 hours postprandially and at bedtime. In patients with duodenal ulcers, antacids are usually given for 4-6 weeks, and in patients with gastric ulcers, antacids are administered until healing is complete.
If symptoms of duodenal ulcer recur, some clinicians recommend that antacids be administered 1 and 3 hours postprandially and at bedtime for 1 week and, if pain is relieved, less frequently for an additional 1-2 weeks; these patients should consult their physicians if pain worsens or is not relieved after the first week of therapy. Additional doses of antacids may be administered to relieve ulcer pain which occurs between regularly scheduled doses.
For the acute management of moderate or severe esophageal reflux, an antacid suspension is administered every hour; if symptoms persist, antacids may be given every 30 minutes. For long-term therapy of esophageal reflux, antacids are administered 1 and 3 hours postprandially and at bedtime and whenever symptoms recur.
In the management of GI bleeding and stress ulceration, antacids are usually administered every hour and, for GI bleeding, the antacid dosage should be titrated to maintain the nasogastric aspirate above pH 3.5. For severe symptoms, antacid suspensions may be diluted with water or milk and given by continuous intragastric infusion.
To reduce the risk of anesthesia-induced gastric acid aspiration, an antacid suspension has been given 30 minutes before anesthesia.
In conjunction with dietary phosphate restriction in the management of hyperphosphatemia, 30-40 mL of aluminum hydroxide or aluminum carbonate suspension is administered 3 or 4 times daily.
Dosage of cimetidine hydrochloride is expressed in terms of cimetidine.
The usual adult IM or IV dosage of cimetidine is 300 mg every 6-8 hours. If necessary, parenteral dosage may be increased by increasing the frequency of administration, but the manufacturer recommends that IM or intermittent IV dosage not exceed 2.4 g daily.
When feasible, IV dosage should be adjusted to maintain an intragastric pH of 5 or greater.
When cimetidine is administered by continuous IV infusion in adults, the drug usually is infused at a rate of 37.5 mg/hour, but the rate should be individualized according to patient requirements. For patients requiring more rapid increases in GI pH, an initial 150-mg IV loading dose may be required.
In one study in patients with pathologic hypersecretory conditions, the average dosage by continuous IV infusion required to maintain gastric acid secretion at 10 or less mEq/hour was 160 mg/hour, but individual requirements varied considerably, ranging from 40-600 mg/hour.
For the prevention of upper GI bleeding in critically ill patients, cimetidine usually is administered to adults by continuous IV infusion at a rate of 50 mg/hour for up to 7 days; the manufacturer states that the safety and efficacy of continuously infused cimetidine for more prolonged periods have not been established. The manufacturer also indicates that an initial loading dose is not required when the drug is administered prophylactically in such patients. However, some clinicians recommend initiating cimetidine therapy in critically ill patients with a 300-mg IV loading dose administered over 5-20 minutes, followed by a continuous IV infusion initiated at a rate of 37.5-50
mg/hour and titrated according to gastric pH (e.g., maintenance of a pH of at least 3.5-4) by additional 25-mg/hour increments, generally up to a maximum rate of 100 mg/hour. Intermittent IV doses of the drug appear to be less effective in preventing upper GI bleeding than continuous IV infusions.
In the treatment of upper GI bleeding+, peptic esophagitis+, and stress ulcers+, IV or oral dosage of 1-2 g daily, administered in 4 divided doses, has been used.
When the potential benefits are thought to outweigh the possible risks, a pediatric cimetidine dosage of 20-40 mg/kg daily in divided doses has been used in a limited number of children.
Accumulation of cimetidine may occur in patients with severe renal failure; therefore, the lowest effective dosage of the drug should be used. In patients with creatinine clearances of less than 30 mL/minute, the manufacturer recommends oral or IV cimetidine dosage of 300 mg every 12 hours. Dosage may be adjusted on the basis of gastric acid secretory response.
Dosage intervals may be cautiously decreased from every 12 hours to every 8 hours or less, if necessary. In patients with severe renal impairment, accumulation of the drug may occur and the longest dosage interval compatible with an adequate response should be used. For the prevention of upper GI bleeding in critically ill patients, the manufacturer states that patients with renal impairment (creatinine clearance less than 30 mL/minute) can receive one half of the usual cimetidine dosage.
When hepatic impairment is also present, further reduction in dosage may be necessary. Because hemodialysis greatly reduces blood cimetidine concentrations, cimetidine should be administered at the end of dialysis and every 12 hours during the interdialysis period.
Cimetidine and cimetidine hydrochloride are administered orally. Cimetidine hydrochloride may also be given by IM or slow IV injection or by intermittent or continuous slow IV infusion, in hospitalized patients with pathologic hypersecretory conditions or intractable ulcer, or when oral therapy is not feasible. Antacids may be given as necessary for relief of pain in patients with ulcers but should not be administered simultaneously with oral cimetidine.
Commercially available prefilled syringes of cimetidine hydrochloride are intended for IM injection or for preparation of IV admixtures; because the drug must be diluted prior to IV administration, the prefilled syringemust not be used for direct IV injection. Parenteral solutions of cimetidine hydrochloride should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.
Commercially available prefilled syringes of cimetidine hydrochloride are intended for IM injection or for preparation of IV admixtures; because the drug must be diluted prior to IV administration, the prefilled syringemust not be used for direct IV injection. Parenteral solutions of cimetidine hydrochloride should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit.
| DRUG LABEL | DOSING TYPE | DOSING INSTRUCTIONS |
|---|---|---|
| CVS HEARTBURN RELIEF 200 MG TB | Maintenance | Adults take 1 tablet (200 mg) by oral route 2 times per day 30 minutes before meals |
| DRUG LABEL | DOSING TYPE | DOSING INSTRUCTIONS |
|---|---|---|
| CIMETIDINE 200 MG TABLET | Maintenance | Adults take 1 tablet (200 mg) by oral route 2 times per day 30 minutes before meals |
The following drug interaction information is available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide):
There are 6 contraindications.
These drug combinations generally should not be dispensed or administered to the same patient. A manufacturer label warning that indicates the contraindication warrants inclusion of a drug combination in this category, regardless of clinical evidence or lack of clinical evidence to support the contraindication.
| Drug Interaction | Drug Names |
|---|---|
| Dofetilide/MATE Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: The active tubular secretion of dofetilide is inhibited by renal cation transport inhibitors.(1) CLINICAL EFFECTS: The concurrent administration of dofetilide with renal cation transport inhibitors may result in elevated levels and increased effects of dofetilide including QT prolongation or torsades de pointes.(1) PREDISPOSING FACTORS: Renal impairment may increase risk for excessive QTc prolongation as dofetilide is primarily renally eliminated. To prevent increased serum levels and risk for ventricular arrhythmias, dofetilide must be dose adjusted for creatinine clearance < or = to 60 mL/min.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The manufacturer of dofetilide states that the concurrent administration of dofetilide with renal cation transport inhibitors is contraindicated. The manufacturer suggests that agents that have no effect on dofetilide plasma levels, such as aluminum and magnesium hydroxide antacids, omeprazole, or ranitidine, be used as alternatives to cimetidine. If dofetilide is to be discontinued, a washout of at least 2 days is recommendation prior to starting cimetidine.(1) DISCUSSION: Dofetilide is primarily excreted in the urine via both glomerular filtration and active tubular secretion via the cation transport system. Cimetidine is believed to inhibit the cation transport system.(1) The concurrent administration of dofetilide (500 mcg twice daily) with cimetidine (400 mg twice daily) resulted in an increase in dofetilide plasma levels by 58%. The concurrent administration of dofetilide (500 mcg single dose) with cimetidine (100 mg twice daily) resulted in an increase in dofetilide plasma levels by 13%.(1) Therefore, the manufacturer of dofetilide states that the concurrent administration of dofetilide and cimetidine is contraindicated. The manufacturer suggests that agents that have no effect on dofetilide plasma levels, such as aluminum and magnesium hydroxide antacids, omeprazole, or ranitidine, be used as alternatives to cimetidine.(1) MATE renal transport inhibitors include: cimetidine, pyrimethamine, risdiplam, and vandetanib.(3) |
DOFETILIDE, TIKOSYN |
| Epirubicin/Cimetidine SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: The exact mechanism is unknown, but it is not believed to involve decreased CYP P-450 activity or decreased liver blood flow.(1) CLINICAL EFFECTS: Concurrent use of cimetidine may result in elevated levels of and toxicity from epirubicin.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of epirubicin states that cimetidine therapy should be discontinued prior to epirubicin use.(2) DISCUSSION: In a study in 8 patients, subjects received epirubicin (100 mg/m2) every 3 weeks with and without oral cimetidine (400 mg twice daily) for 7 days starting 5 days before epirubicin. Cimetidine increased the area-under-curve (AUC) of epirubicin, epirubicinol, and 7-deoxy-doxorubicinol aglycone by 50%, 41%, and 357%, respectively.(1) The clearance of epirubicin decreased by 30%.(2) |
ELLENCE, EPIRUBICIN HCL |
| Zolmitriptan (Greater Than 2.5 mg)/Cimetidine SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Cimetidine inhibits the CYP1A2 mediated metabolism of zolmitriptan and its active N-desmethyl metabolite.(1,2) CLINICAL EFFECTS: Increased concentrations of zolmitriptan and its active N-desmethyl metabolite may increase the risk for adverse effects such as paresthesia, dizziness, or sensation of heaviness or tightness in the neck/throat/jaw, or chest.(1) PREDISPOSING FACTORS: Due to the extended half-life associated with concurrent cimetidine use, multiple doses of zolmitriptan within a 24-hour period may lead to accumulation, increasing the risk for adverse effects.(1,2) PATIENT MANAGEMENT: The manufacturer of zolmitriptan recommends the maximum single dose be reduced to 2.5 mg, not to exceed 5 mg in any 24-hour period.(1) When possible, consider use of an alternative acid reducing agent. DISCUSSION: Zolmitriptan is converted to several metabolites, but only the N-desmethyl metabolite is active. Although plasma concentrations are about 2/3 of the parent drug, the N-desmethyl metabolite is 2 to 6 times more potent at 5-HT1B/1D receptors than zolmitriptan and may contribute substantially to its pharmacologic effect.(1) Zolmitriptan added to therapeutic doses of cimetidine 400 mg three times a day increased the area-under-curve(AUC) for zolmitriptan and its active N-desmethyl metabolite of approximately 1.5 fold and 2 fold respectively.(1,2) An open 2 period crossover study in 16 volunteer subjects evaluated the pharmacokinetics of zolmitriptan and the N-desmethyl metabolite with or without cimetidine 400mg every 8 hours for 2 days. After cimetidine treatment, the AUC of zolmitriptan and the N-desmethyl metabolite increased 1.48 and 2.05 fold respectively. The half-life of zolmitriptan increased from 4.99 to 7.19 hours, while the active metabolite half-life increased from 3.81 to 8.00 hours after treatment with cimetidine.(2) |
ZOLMITRIPTAN, ZOLMITRIPTAN ODT, ZOMIG |
| Lemborexant (Greater Than 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(1,2) |
DAYVIGO |
| Fezolinetant/CYP1A2 Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: Inhibitors of CYP1A2 may inhibit the metabolism of fezolinetant.(1-4) CLINICAL EFFECTS: Concurrent use of a CYP1A2 inhibitor may increase levels of and adverse effects from fezolinetant.(1-4) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Recommendations for concurrent use of fezolinetant with CYP1A2 inhibitors differ in different regions. The US manufacturer of fezolinetant states that concurrent use with strong, moderate, and weak CYP1A2 inhibitors is contraindicated.(1) The Australian, Canadian, and UK manufacturers of fezolinetant state that concurrent use with strong and moderate CYP1A2 inhibitors is contraindicated, while weak CYP1A2 inhibitors are not predicted to cause clinically relevant changes in fezolinetant exposure.(2-4) DISCUSSION: In a study, fluvoxamine, a strong CYP1A2 inhibitor, increased fezolinetant maximum concentration (Cmax) and area-under-curve (AUC) by 80% and 840%, respectively. Mexiletine (400 mg every 8 hours), a moderate CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 40% and 360%, respectively. Cimetidine (300 mg every 6 hours), a weak CYP1A2 inhibitor, increased fezolinetant Cmax and AUC by 30% and 100%, respectively.(1) Strong CYP1A2 inhibitors linked to this monograph include angelica root, ciprofloxacin, enasidenib, enoxacin, fluvoxamine, and rofecoxib. Moderate CYP1A2 inhibitors linked to this monograph include capmatinib, dipyrone, fexinidazole, genistein, hormonal contraceptives, methoxsalen, mexiletine, osilodrostat, phenylpropanolamine, pipemidic acid, rucaparib, troleandomycin, vemurafenib, and viloxazine. Weak CYP1A2 inhibitors linked to this monograph include allopurinol, artemisinin, caffeine, cannabidiol, cimetidine, curcumin, dan-shen, deferasirox, disulfiram, Echinacea, famotidine, ginseng, norfloxacin, obeticholic acid, parsley, piperine, propafenone, propranolol, ribociclib, simeprevir, thiabendazole, ticlopidine, triclabendazole, verapamil, zileuton.(5-7) |
VEOZAH |
| Colchicine (for Cardioprotection)/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 1-Contraindicated Drug Combination: This drug combination is contraindicated and generally should not be dispensed or administered to the same patient. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2) CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2) PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal or hepatic impairment.(1,2) PATIENT MANAGEMENT: The manufacturer of colchicine used for cardiovascular risk reduction states that concurrent use of colchicine with P-gp inhibitors is contraindicated.(1) DISCUSSION: There are several reports of colchicine toxicity(3-5) and death(6,7) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(8) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(9) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vimseltinib, and voclosporin.(1,10,11) |
LODOCO |
There are 41 severe interactions.
These drug interactions can produce serious consequences in most patients. Actions required for severe interactions include, but are not limited to, discontinuing one or both agents, adjusting dosage, altering administration scheduling, and providing additional patient monitoring. Review the full interaction monograph for more information.
| Drug Interaction | Drug Names |
|---|---|
| Selected Anticoagulants (Vit K antagonists)/Cimetidine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Cimetidine is a weak inhibitor of CYP1A2, CYP2C9, and CYP3A4. The more potent S-warfarin isomer is metabolized by CYP2C9 where as the weaker warfarin R-enantiomer is metabolized by CYP1A2 and CYP3A4. The cimetidine inhibitory effect appears to be greater on the less active R-warfarin isomer. CLINICAL EFFECTS: The pharmacologic effects of warfarin may be increased resulting in a higher risk for bleeding. PREDISPOSING FACTORS: Interaction magnitude is expected to be greater with use of prescription doses of cimetidine, e.g. 800 mg to 1,600 mg daily. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). Pharmacogenomic information: warfarin patients with a CYP2C9 intermediate metabolizer genotype, and/or 1-2 copies of a reduced function VKORC1 gene are expected to be more susceptible to this interaction. Although patients with a pre-existing CYP2C9 poor metabolizer genotype are expected to be less susceptible to effects from this drug combination, their reduced function genotypes (e.g. CYP2C9 *1/*3, *2/*2, *2/*3, and *3/*3) result in an inherently higher warfarin half-life and risk for warfarin-associated bleeding. CYP2C9 poor metabolizers generally require lower anticoagulant doses and more time (>2 to 4 weeks) to achieve effective and safe anticoagulation than patients without these CYP2C9 variants. PATIENT MANAGEMENT: Given the availability of alternatives, coadministration of cimetidine and warfarin should be avoided, particularly if high doses of cimetidine are prescribed. Consider use of H-2 antagonists famotidine or nizatidine which are unlikely to interact with warfarin. If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. The time of highest risk for a coumarin-type drug interaction is when the precipitant drug is initiated or discontinued. Contact the prescriber before initiating, altering the dose or discontinuing either drug. DISCUSSION: The majority of drug interaction reports involving H-2 antagonists and warfarin have occurred with cimetidine. Reports of a possibly significant interaction between ranitidine and warfarin have been equivocal. Famotidine and nizatidine do not appear to affect prothrombin time. A study of 6 healthy subjects receiving cimetidine and warfarin concomitant therapy had no significant effect on the S-warfarin however increased R-warfarin trough concentrations 28% (p<0.05) and decreased R-warfarin clearance by 23% (p<0.05). |
ANISINDIONE, DICUMAROL, JANTOVEN, PHENINDIONE, WARFARIN SODIUM |
| Carmustine/Cimetidine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The exact mechanism is unknown. Both carmustine and cimetidine have bone marrow suppression properties, which may be additive during concurrent therapy. It has also been suggested that cimetidine may inhibit the metabolism of carmustine.(1) CLINICAL EFFECTS: Cimetidine may enhance carmustine-induced bone marrow suppression, including leukopenia and neutropenia. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid concomitant use of these medications. If the drugs are used together, monitor for excessive bone marrow toxicity. Since other H-2 antagonists (e.g., ranitidine, famotidine) do not appear to interact, substituting cimetidine with one of these agents may be desirable. However, if a patient is already receiving this combination and is not experiencing adverse effects, substitution is probably not necessary. DISCUSSION: Additive bone marrow depression was seen in patients receiving concurrent therapy with carmustine and cimetidine when compared to control patients not receiving cimetidine.(2,3) In an animal study, rats were given a single injection of cimetidine at various times up to 30 minutes before or up to 60 minutes after a carmustine injection. Enhanced carmustine bone marrow toxicity was seen with concurrent administration of cimetidine.(4) |
BICNU, CARMUSTINE, GLIADEL |
| Theophylline Derivatives/Cimetidine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Cimetidine inhibits the metabolism of theophylline by CYP1A2.(1-10) The duration of cimetidine's inhibitory action is uncertain. Short-term cimetidine therapy appears to reverse rapidly(2) but may persist in prolonged therapy. Increased pentoxifylline serum levels may be the result of an increase in the oral bioavailability of pentoxifylline.(11) CLINICAL EFFECTS: Concurrent cimetidine and theophylline derivative therapy may result in elevated theophylline derivative concentration levels, prolonged elimination half-life, and decreased clearance. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Theophylline derivative blood levels should be very closely monitored if cimetidine therapy is to be initiated, changed, or discontinued. Theophylline has a narrow therapeutic range; therefore, dosage reductions up to 30-50%(4) should be considered to prevent intoxication when cimetidine therapy is started. Antacids, famotidine, or possibly ranitidine might be more judicious choices than cimetidine in patients receiving theophylline derivatives. DISCUSSION: It is well documented that cimetidine impairs the elimination of theophylline when the two agents are co-administered to patients.(1-10, 12-22) This interaction has been noted by a variety of routes including continuous intravenous infusion.(22) Reports indicate that with concurrent cimetidine, theophylline plasma concentrations increase, theophylline half-life is prolonged from 29% to 73%(1-3;9,12-14) and theophylline clearance is decreased by 18.5% to 46%.(1-3,9,13,23) Age and smoking do not appear to affect the magnitude of the interaction.(17,18,20) Significant changes can be seen within 24 hours(3,5) and may progress as co-therapy continues.(3) A study involving ten healthy patients demonstrated that concomitant administration of cimetidine significantly decreased the plasma clearance of oxtriphylline.(24) Aminophylline is involved in a similar interaction as theophylline as seen in one case report.(25) In one report cimetidine also decreased the clearance and prolonged the half-life of caffeine.(26,27) A study demonstrated that cimetidine caused a significant increase in plasma levels of pentoxifylline.(11) Information on ranitidine is conflicting. Several studies have shown that ranitidine does not influence theophylline.(9,15,16,19,28,29) One case report noted toxic theophylline levels after ranitidine;(30) however, this case report has been challenged.(31) In another case report, theophylline levels rose from 16.6 mcg/ml to 39.7 mcg/ml(32) when the patient was given ranitidine. Other reports have also noted a reduction in theophylline elimination by ranitidine.(33,34) Famotidine has shown to have no effect on theophylline metabolism in a clinical trial;(35) however, there is one case report of decreased theophylline clearance during famotidine therapy.(36) Dyphylline, a theophylline derivative that is not converted to theophylline in vivo, is not to be expected to interact with cimetidine. A study showed that cimetidine increased the average steady state plasma concentration of pentoxifylline and its metabolite by 25% and 30%, respectively.(37) |
ACETAMIN-CAFF-DIHYDROCODEINE, AMINOPHYLLINE, ASA-BUTALB-CAFFEINE-CODEINE, ASCOMP WITH CODEINE, BUTALB-ACETAMINOPH-CAFF-CODEIN, BUTALBITAL-ACETAMINOPHEN-CAFFE, BUTALBITAL-ASPIRIN-CAFFEINE, CAFCIT, CAFFEINE, CAFFEINE AND SODIUM BENZOATE, CAFFEINE CITRATE, ELIXOPHYLLIN, ERGOTAMINE-CAFFEINE, FIORICET, FIORICET WITH CODEINE, MIGERGOT, NORGESIC, NORGESIC FORTE, ORPHENADRINE-ASPIRIN-CAFFEINE, ORPHENGESIC FORTE, PENTOXIFYLLINE, THEO-24, THEOPHYLLINE, THEOPHYLLINE ANHYDROUS, THEOPHYLLINE ER, THEOPHYLLINE ETHYLENEDIAMINE, TREZIX |
| Deferasirox/Aluminum Salts SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Decreased absorption of deferasirox possibly from complex formation with the aluminum salt. CLINICAL EFFECTS: The therapeutic effects of deferasirox may be reduced. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of deferasirox states patients taking deferasirox should not take aluminum salts or aluminum-containing antacid products. DISCUSSION: Simultaneous administration of deferasirox and aluminum has not been studied. Even though deferasirox has a lower affinity for aluminum than iron, it should not be taken with aluminum-containing products. |
DEFERASIROX, EXJADE, JADENU, JADENU SPRINKLE |
| Oral Phosphate Supplements; Urinary pH Modifiers/Aluminum; Calcium; Magnesium SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Medications containing significant amounts of aluminum, calcium, or magnesium may bind to the phosphate and prevent its absorption.(1) CLINICAL EFFECTS: Concurrent use of medications containing significant amounts of aluminum, calcium, or magnesium may result in decreased effectiveness of phosphate supplements and urinary pH modifiers high in phosphate.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Patients receiving phosphate supplements or urinary pH modifiers high in phosphate should be instructed to avoid medications containing aluminum, calcium, or magnesium.(1) Some phosphate laxative products used as phosphate supplements may contain sufficient quantities of phosphate to interact as well. DISCUSSION: The manufacturer of K-Phos states that products containing aluminum, calcium, or magnesium may bind to the phosphate and prevent its absorption. Therefore, patients receiving phosphate supplements and urinary pH modifiers high in phosphate should be instructed to avoid products containing aluminum, calcium, or magnesium.(1) |
K-PHOS NO.2, K-PHOS ORIGINAL, POTASSIUM PHOSPHATE, SODIUM PHOSPHATE DIBASIC, UROQID-ACID NO.2 |
| Solid Oral Potassium Tablets/Anticholinergics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concentrated potassium may damage the lining of the GI tract. Anticholinergics delay gastric emptying, resulting in the potassium product remaining in the gastrointestinal tract for a longer period of time.(1-16) CLINICAL EFFECTS: Use of solid oral dosage forms of potassium in patients treated with anticholinergics may result in gastrointestinal erosions, ulcers, stenosis and bleeding.(1-16) PREDISPOSING FACTORS: Diseases or conditions which may increase risk for GI damage include: preexisting dysphagia, strictures, cardiomegaly, diabetic gastroparesis, elderly status, or insufficient oral intake to allow dilution of potassium.(1-10,21) Other drugs which may add to risk for GI damage include: nonsteroidal anti-inflammatory drugs (NSAIDs), bisphosphonates, or tetracyclines.(21) PATIENT MANAGEMENT: Regulatory agency and manufacturer recommendations regarding this interaction: - In the US, all solid oral dosage forms (including tablets and extended release capsules) of potassium are contraindicated in patients receiving anticholinergics at sufficient dosages to result in systemic effects.(2-8) Patients receiving such anticholinergic therapy should use a liquid form of potassium chloride.(2) - In Canada, solid oral potassium is contraindicated in any patient with a cause for arrest or delay in tablet/capsule passage through the gastrointestinal tract and the manufacturers recommend caution with concurrent anticholinergic medications.(1,9-10) Evaluate each patient for predisposing factors which may increase risk for GI damage. In patients with multiple risk factors for harm, consider use of liquid potassium supplements, if tolerated. For patients receiving concomitant therapy, assure any potassium dose form is taken after meals with a large glass of water or other fluid. To decrease potassium concentration in the GI tract, limit each dose to 20 meq; if more than 20 meq daily is required, give in divided doses.(2) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Patients should be instructed to immediately report any difficulty swallowing, abdominal pain, distention, severe vomiting, or gastrointestinal bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: In clinical trials, there was a higher incidence of gastric and duodenal lesions in patients receiving a high dose of a wax-matrix controlled-release formulation with a concurrent anticholinergic agent. Some lesions were asymptomatic and not accompanied by bleeding, as shown by a lack of positive Hemoccult tests.(1-17) Several studies suggest that the incidence of gastric and duodenal lesions may be less with the microencapsulated formulation of potassium chloride.(14-17) |
KLOR-CON 10, KLOR-CON 8, KLOR-CON M10, KLOR-CON M15, KLOR-CON M20, POTASSIUM CHLORIDE, POTASSIUM CITRATE ER, UROCIT-K |
| Tizanidine/Cimetidine; Famotidine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Cimetidine and famotidine may inhibit the metabolism of tizanidine by CYP1A2.(1) CLINICAL EFFECTS: Concurrent use of cimetidine or famotidine may result in elevated levels of and effects from tizanidine, including hypotension, bradycardia, drowsiness, sedation, and decreased psychomotor function. PREDISPOSING FACTORS: The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(2) PATIENT MANAGEMENT: The US manufacturer of tizanidine states that concurrent use of tizanidine with inhibitors of CYP1A2, such as cimetidine or famotidine, should be avoided. If concurrent use is warranted, tizanidine should be initiated with 2 mg dose and increased in 2-4 mg steps daily based on patient response to therapy.(1) If adverse reactions such as hypotension, bradycardia, or excessive drowsiness occur, reduce or discontinue tizanidine therapy.(1) DISCUSSION: In a study in 10 healthy subjects, concurrent fluvoxamine, another inhibitor of CYP1A2, increased tizanidine maximum concentration (Cmax), area-under-curve (AUC), and half-life (T1/2) by 12-fold, 33-fold, and 3-fold, respectively. Significant decreases in blood pressure and increases in drowsiness and psychomotor impairment occurred.(1) In a study in 10 healthy subjects, concurrent ciprofloxacin, another inhibitor of CYP1A2, increase tizanidine Cmax and AUC by 7-fold and 10-fold, respectively. Significant decreases in blood pressure and and increases in drowsiness and psychomotor impairment occurred.(1) |
TIZANIDINE HCL, ZANAFLEX |
| Posaconazole Suspension/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: H2 antagonists and proton pump inhibitors (PPIs) increase the stomach pH, possibly reducing gastrointestinal absorption of posaconazole suspension. CLINICAL EFFECTS: Concurrent use of H2 antagonists or proton pump inhibitors (PPIs) may result in decreased effectiveness of posaconazole suspension. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid the concurrent use of posaconazole suspension with H2 antagonists or proton pump inhibitors (PPIs).(1) If H2 antagonists or PPI therapy is required, use the tablet formulation or powder mix formulation of posaconazole. DISCUSSION: Concurrent cimetidine (400 mg twice daily) decreased both posaconazole (200 mg daily) maximum concentration (Cmax) and area-under-curve (AUC) levels by 39%.(1) No significant effects with other H2 blockers have been noted.(1) Esomeprazole (40 mg daily for 3 days) decreased the Cmax and AUC of a single dose of posaconazole suspension (400 mg) by 46% and 32%, respectively.(1) In a study of posaconazole levels in patients with acute myeloid leukemia or myelodysplastic syndrome, use of pantoprazole was associated with decreased posaconazole levels.(3) In a cross-over study in 5 healthy subjects, esomeprazole decreased the Cmax and AUC of posaconazole suspension by 37% and 84%, respectively. Simultaneous intake of Coca-Cola did not completely counteract the effects of esomeprazole.(4) In a study in healthy subjects, esomeprazole decreased the Cmax and AUC of posaconazole suspension by 55% and 49%, respectively. Simultaneous intake of Coca-Cola did not completely counteract the effects of esomeprazole.(5) |
NOXAFIL, POSACONAZOLE |
| Dabigatran/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Dabigatran etexilate is a substrate for the P-glycoprotein (P-gp) system. Inhibition of intestinal P-gp leads to increased absorption of dabigatran.(1-3) CLINICAL EFFECTS: The concurrent use dabigatran with P-gp inhibitors may lead to elevated plasma levels of dabigatran, increasing the risk for bleeding. PREDISPOSING FACTORS: Factors associated with an increased risk for bleeding include renal impairment, concomitant use of P-gp inhibitors, patient age >74 years, coexisting conditions (e.g. recent trauma) or use of drugs (e.g. NSAIDs) associated with bleeding risk, and patient weight < 50 kg.(1-4) PATIENT MANAGEMENT: Assess renal function and evaluate patient for other pre-existing risk factors for bleeding prior to initiating concurrent therapy. The US manufacturer of dabigatran states that the concurrent use of dabigatran and P-gp inhibitors should be avoided in atrial fibrillation patients with severe renal impairment (CrCl less than 30 ml/min) and in patients with moderate renal impairment (CrCl less than 50 ml/min) being treated for or undergoing prophylaxis for deep vein thrombosis (DVT) or pulmonary embolism (PE). The interaction with P-gp inhibitors can be minimized by taking dabigatran several hours apart from the P-gp inhibitor dose.(1) The concomitant use of dabigatran with P-gp inhibitors has not been studied in pediatric patients but may increase exposure to dabigatran.(1) While the US manufacturer of dabigatran states that no dosage adjustment is necessary in other patients,(1) the Canadian manufacturer of dabigatran states that concomitant use of strong P-gp inhibitors (e.g., glecaprevir-pibrentasvir) is contraindicated. When dabigatran is used for the prevention of venous thromboembolism (VTE) after total hip or knee replacement concurrently with amiodarone, quinidine, or verapamil, the dose of dabigatran should be reduced from 110 mg twice daily to 150 mg once daily. For patients with CrCl less than 50 ml/min on verapamil, a further dabigatran dose reduction to 75 mg once daily should be considered. Verapamil should be given at least 2 hours after dabigatran to minimize the interaction.(2) The UK manufacturer of dabigatran also states the use of dabigatran with strong P-gp inhibitors (e.g., cyclosporine, glecaprevir-pibrentasvir or itraconazole) is contraindicated. Concurrent use of ritonavir is not recommended. When dabigatran is used in atrial fibrillation patients and for treatment of DVT and PE concurrently with verapamil, the UK manufacturer recommends reducing the dose of dabigatran from 150 mg twice daily to 110 mg twice daily, taken simultaneously with verapamil. When used for VTE prophylaxis after orthopedic surgery concurrently with amiodarone, quinidine, or verapamil, the dabigatran loading dose should be reduced from 110 mg to 75 mg, and the maintenance dose should be reduced from 220 mg daily to 150 mg daily, taken simultaneously with the P-gp inhibitor. For patients with CLcr 30-50 mL/min on concurrent verapamil, consider further lowering the dabigatran dose to 75 mg daily.(3) If concurrent therapy is warranted, monitor patients for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Consider regular monitoring of hemoglobin, platelet levels, and/or activated partial thromboplastin time (aPTT) or ecarin clotting time (ECT). When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: When dabigatran was co-administered with amiodarone, the extent and rate of absorption of amiodarone and its active metabolite DEA were essentially unchanged. The dabigatran area-under-curve (AUC) and maximum concentration (Cmax) were increased by about 60% and 50%, respectively;(1,2) however, dabigatran clearance was increased by 65%.(1) Pretreatment with quinidine (200 mg every 2 hours to a total dose of 1000 mg) increased the AUC and Cmax of dabigatran by 53% and 56%, respectively.(1,2) Chronic administration of immediate release verapamil one hour prior to dabigatran dose increased dabigatran AUC by 154%.(4) Administration of dabigatran two hours before verapamil results in a negligible increase in dabigatran AUC.(1) Administration of sofosbuvir-velpatasvir-voxilaprevir (400/100/200 mg daily) increased the Cmax and AUC of a single dose of dabigatran (75 mg) by 2.87-fold and 2.61-fold, respectively.(5) Simultaneous administration of glecaprevir-pibrentasvir (300/120 mg daily) with a single dose of dabigatran (150 mg) increased the Cmax and AUC by 2.05-fold and 2.38-fold, respectively.(6) A retrospective comparative effectiveness cohort study including data from 9,886 individuals evaluated adverse bleeding rates with standard doses of oral anticoagulants with concurrent verapamil or diltiazem in patients with nonvalvular atrial fibrillation and normal kidney function. The study compared rates of bleeding following co-administration of either dabigatran, rivaroxaban, or apixaban with verapamil or diltiazem, compared to co-administration with amlodipine or metoprolol. Results of the study found that concomitant dabigatran use with verapamil or diltiazem was associated with increased overall bleeding (hazard ratio (HR) 1.52; 95% confidence interval (CI), 1.05-2.20, p<0.05) and increased overall GI bleeding (HR 2.16; 95% CI, 1.30-3.60, p<0.05) when compared to amlodipine. When compared to metoprolol, concomitant dabigatran use with verapamil or diltiazem was also associated with increased overall bleeding (HR, 1.43; 95% CI, 1.02-2.00, p<0.05) and increased overall GI bleeding (HR, 2.32; 95% CI, 1.42-3.79, p<0.05). No association was found between increased bleeding of any kind and concurrent use of rivaroxaban or apixaban with verapamil or diltiazem.(7) A summary of pharmacokinetic interactions with dabigatran and amiodarone or verapamil concluded that concurrent use is considered safe if CrCl is greater than 50 ml/min but should be avoided if CrCl is less than 50 ml/min in VTE and less than 30 ml/min for NVAF. Concurrent use with diltiazem was considered safe.(9) P-gp inhibitors include amiodarone, asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, conivaptan, cyclosporine, daclatasvir, danicopan, daridorexant, diosmin, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir, indinavir, itraconazole, ivacaftor, josamycin, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir, propafenone, quinidine, ranolazine, ritonavir, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, voclosporin, and voxilaprevir.(1-9) |
DABIGATRAN ETEXILATE, PRADAXA |
| Topotecan/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of P-glycoprotein may increase the absorption of topotecan.(1) CLINICAL EFFECTS: The concurrent administration of topotecan with an inhibitor of P-glycoprotein may result in elevated levels of topotecan and signs of toxicity. These signs may include but are not limited to anemia, diarrhea, and thrombocytopenia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of topotecan states that the use of topotecan and P-glycoprotein inhibitors should be avoided. If concurrent use is warranted, carefully monitor patients for adverse effects.(1) DISCUSSION: In clinical studies, the combined use of elacridar (100 mg to 1000 mg) increased the area-under-curve (AUC) of topotecan approximately 2.5-fold.(1) Oral cyclosporine (15 mg/kg) increased the AUC of topotecan lactone and total topotecan to 2-fold to 3-fold of the control group, respectively.(1) P-gp inhibitors linked to this monograph include: adagrasib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, bosutinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, ginseng, hydroquinidine, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pibrentasvir/glecaprevir, propafenone, quinidine, ranolazine, selpercatinib, sotorasib, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(2,3) |
HYCAMTIN |
| Solid Oral Potassium Capsules/Anticholinergics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Concentrated potassium may damage the lining of the GI tract. Anticholinergics delay gastric emptying, resulting in the potassium product remaining in the gastrointestinal tract for a longer period of time.(1-16)) CLINICAL EFFECTS: Use of solid oral dosage forms of potassium in patients treated with anticholinergics may result in gastrointestinal erosions, ulcers, stenosis and bleeding.(1-16) PREDISPOSING FACTORS: Diseases or conditions which may increase risk for GI damage include: preexisting dysphagia, strictures, cardiomegaly, diabetic gastroparesis, elderly status, or insufficient oral intake to allow dilution of potassium.(1-10,21) Other drugs which may add to risk for GI damage include: nonsteroidal anti-inflammatory drugs (NSAIDs), bisphosphonates, or tetracyclines.(21) PATIENT MANAGEMENT: Regulatory agency and manufacturer recommendations regarding this interaction: - In the US, all solid oral dosage forms (including tablets and extended release capsules) of potassium are contraindicated in patients receiving anticholinergics at sufficient dosages to result in systemic effects.(2-8) Patients receiving such anticholinergic therapy should use a liquid form of potassium chloride.(2) - In Canada, solid oral potassium is contraindicated in any patient with a cause for arrest or delay in tablet/capsule passage through the gastrointestinal tract and the manufacturers recommend caution with concurrent anticholinergic medications.(1,9-10) Evaluate each patient for predisposing factors which may increase risk for GI damage. In patients with multiple risk factors for harm, consider use of liquid potassium supplements, if tolerated. For patients receiving concomitant therapy, assure any potassium dose form is taken after meals with a large glass of water or other fluid. To decrease potassium concentration in the GI tract, limit each dose to 20 meq; if more than 20 meq daily is required, give in divided doses.(2) If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. Patients should be instructed to immediately report any difficulty swallowing, abdominal pain, distention, severe vomiting, or gastrointestinal bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: In clinical trials, there was a higher incidence of gastric and duodenal lesions in patients receiving a high dose of a wax-matrix controlled-release formulation with a concurrent anticholinergic agent. The lesions were asymptomatic and not accompanied by bleeding, as shown by a lack of positive Hemoccult tests.(1-17) Several studies suggest that the incidence of gastric and duodenal lesions may be less with the microencapsulated formulation of potassium chloride.(14-17) |
POTASSIUM CHLORIDE |
| Clopidogrel/Esomeprazole; Omeprazole; Cimetidine SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Clopidogrel is a prodrug and is converted to its active metabolite via a 2 step process. The first conversion step is mediated by CYP2C19, CYP1A2 and CYP2B6, while the second step is mediated by CYP3A4, CYP2B6 and CYP2C19.(1,2) CYP2C19 contributes to both steps and is thought to be the more important enzyme involved in formation of the pharmacologically active metabolite.(1) Proton pump inhibitors (PPIs) may inhibit CYP2C19 mediated conversion to the active metabolite of clopidogrel. The magnitude and clinical significance of CYP2C19 inhibition is highly variable between agents.(1) CLINICAL EFFECTS: Concurrent use of esomeprazole, omeprazole, or cimetidine may result in decreased clopidogrel effectiveness, resulting in increased risk of adverse cardiac events. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Evaluate patient risk for gastrointestinal(GI) bleeding. When PPIs are needed, use dexlansoprazole, lansoprazole, pantoprazole or rabeprazole as they have a lower interaction risk.(1,3) Consider the use of H2 blockers (such as famotidine, nizatidine, or ranitidine) in patients with a low bleeding risk and reserve the use of PPIs for patients at higher risk of GI bleeding. US manufacturers for clopidogrel and omeprazole state concurrent use of clopidogrel esomeprazole and omeprazole should be avoided.(1,4-5) As esomeprazole and omeprazole are irreversible inhibitors of CYP2C19, separating clopidogrel from esomeprazole or omeprazole administration times does not change the magnitude of this interaction.(1,4,6) The US manufacturer of clopidogrel states that alternatives to clopidogrel should be considered in patients who are poor metabolizers of CYP2C19.(1) It would be prudent to assume that patients taking strong inhibitors of CYP2C19 are poor metabolizers of this isoenzyme. Moderate CYP2C19 inhibitors, such as omeprazole, and weak CYP2C19 inhibitors, such as cimetidine, may also affect this interaction. Consider alternatives to esomeprazole, omeprazole, and cimetidine in patients stabilized on clopidogrel and alternatives to clopidogrel in patients stabilized on esomeprazole, omeprazole, and cimetidine. If concurrent therapy is warranted, consider appropriate testing to assure adequate inhibition of platelet reactivity. DISCUSSION: US manufacturer for clopidogrel states omeprazole and esomeprazole have been shown to reduce antiplatelet activity of clopidogrel and recommends against concomitant use. The antiplatelet effect of clopidogrel is reduced by approximately 40% in patients receiving 80 mg per day of omeprazole. Dexlansoprazole, lansoprazole and pantoprazole are described as having less effect on clopidogrel antiplatelet activity.(1,3) In the primary literature, documentation for this interaction is conflicting. However, both in-vitro and retrospective analyses indicate that omeprazole decreases the effectiveness of clopidogrel. Although the half-lives of esomeprazole and omeprazole (a racemic mixture of R- and esomeprazole) are short, the effect on CYP2C19 is long lasting because esomeprazole is an irreversible inhibitor of CYP2C19.(6) In two studies in healthy subjects, concurrent omeprazole decreased the effects of clopidogrel on platelets.(7-8) Several studies have found coadministration of clopidogrel with omeprazole resulted in increased platelet aggregation compared to clopidogrel with pantoprazole, or no PPI.(9-12) In a study, use of omeprazole was associated with a decreased risk of upper gastrointestinal bleeding in patients receiving dual antiplatelet therapy with clopidogrel and aspirin. There was no significant difference between the groups in rate of cardiovascular events.(12) Three studies found that simultaneous omeprazole with clopidogrel reduced clopidogrel concentrations and effects.(13-15) In a cross-over trial, healthy subjects received clopidogrel (300 mg loading dose/75 mg daily maintenance dose) and esomeprazole (40 mg oral once daily) co-administered for 30 days. Exposure to the active metabolite of clopidogrel was reduced by 35% to 40% over this time period.(16) In a study in 39 healthy subjects, the effects of omeprazole and rabeprazole on clopidogrel in patients with different CYP2C19 genotypes was examined. In rapid 2C19 metabolizers, simultaneous omeprazole and rabeprazole significantly decreased clopidogrel response. In decreased 2C19 responders, there was wide variation in clopidogrel response and simultaneous omeprazole and rabeprazole had no significant effect on overall clopidogrel effects; however, some subjects became low responders to clopidogrel while on PPI therapy. Staggered dosing of omeprazole had no effect on clopidogrel response in rapid metabolizers, but decreased clopidogrel response in decreased metabolizers.(17) Several retrospective studies found that patients who took clopidogrel with a PPI had increased incidence of major cardiovascular events compared to patients who took clopidogrel without a PPI.(18-22) A retrospective cohort study of 20,596 patients in the Tennessee Medicaid program, evaluated both cardiovascular disease event and GI bleed risk in patients prescribed clopidogrel with or without concurrent PPI use. Pantoprazole was prescribed in 62% of PPI patients. Concomitant PPI and clopidogrel use decreased the risk of hospitalization from GI bleeding by 50%. There was no clear-cut increase risk for serious cardiovascular disease events; however, the 95% CI for this was wide.(23) A post-hoc analysis of the PRINCIPLE-TIMI 44 trial and the TRITON-TIMI trial examined the effects of PPI use on the pharmacodynamic effects and clinical efficacy of clopidogrel. The PRINCIPLE-TIMI 44 trial examined 201 patients undergoing cardiac catheterization with planned percutaneous coronary intervention, 53 of which were taking a PPI at randomization. Patients receiving a PPI had significantly lower rates of inhibition of platelet aggregation at 0.5 hours, 2 hours, 6 hours, and 18-24 hours post-loading dose of clopidogrel. After 15 days of maintenance therapy, there were significantly more non-responders in the group receiving PPI (50% versus 7.9%). The TRITON-TIMI trial examined 13,608 patients who underwent cardiac catheterization with planned percutaneous coronary intervention, 4529 of which were taking a PPI at randomization. Patients received clopidogrel treatment for 6-15 months. There were no significant differences in occurrence of cardiovascular death, non-fatal MI, or non-fatal stroke between patients taking PPIs at randomization and those not; however, use of PPIs was only assessed at randomization and not during the study.(24) |
CLOPIDOGREL, CLOPIDOGREL BISULFATE, PLAVIX |
| Citalopram (Greater Than 20 mg)/Select CYP2C19 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Citalopram is primarily metabolized by the CYP2C19 isoenzyme.(1) CLINICAL EFFECTS: Concurrent use of an agent that inhibits CYP2C19 may result in elevated levels of and toxicity from citalopram, including including risks for serotonin syndrome or prolongation of the QTc interval.(1-5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(5) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, poor metabolizer status at CYP2C19, or higher blood concentrations of citalopram.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,5) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. PATIENT MANAGEMENT: The dose of citalopram should be limited to 20 mg in patients receiving concurrent therapy with an inhibitor of CYP2C19.(1,4) Evaluate the patient for other drugs, diseases and conditions which increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, discontinue other QT prolonging drugs) when possible.(1,2) Weigh the specific benefits versus risks for each patient. The US manufacturer recommends ECG monitoring for citalopram patients with congestive heart failure, bradyarrhythmias, taking concomitant QT prolonging medications or receiving concurrent therapy.(4) Citalopram should be discontinued in patients with persistent QTc measurements greater than 500 ms.(2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: Concurrent use of citalopram (40 mg daily) and cimetidine (400 mg twice daily) for 8 days increased the maximum concentration (Cmax) and area-under-curve (AUC) of citalopram by 39% and 43%, respectively.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, and tecovirimat.(7,8) |
CELEXA, CITALOPRAM HBR |
| Lomitapide (Less Than or Equal To 30 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of lomitapide.(1) Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Thus even weak CYP3A4 inhibitors may affect lomitapide exposure (AUC, area-under-curve). CLINICAL EFFECTS: Concurrent use of a weak inhibitor of CYP3A4 may result in 2-fold increases in lomitapide levels and toxicity from lomitapide.(1) PREDISPOSING FACTORS: This interaction may be more severe in patients with hepatic impairment or with end-stage renal disease.(1) PATIENT MANAGEMENT: The maximum lomitapide dose should be 30 mg daily for patients taking concomitant weak CYP3A4 inhibitors. Due to lomitapide's long half-life, it may take 1 to 2 weeks to see the full effect of this interaction. When initiating a weak CYP3A4 inhibitor in patients taking lomitapide 10 mg daily or more, decrease the dose of lomitapide by 50%. In patients taking lomitapide 5 mg daily, continue current dose. DISCUSSION: Lomitapide is very susceptible to CYP3A4 inhibition. For example, in an interaction study with a strong CYP3A4 inhibitor (ketoconazole) lomitapide exposure was increased 27-fold.(2) Based upon interactions with stronger inhibitors, weak inhibitors of CYP3A4 are predicted to increase lomitapide area-under-curve(AUC) 2-fold.(1) Weak CYP3A4 inhibitors linked to this interaction include alprazolam, amiodarone, amlodipine, asciminib, atorvastatin, azithromycin, Baikal skullcap, belumosudil, bicalutamide, blueberry juice, brodalumab, cannabidiol, capivasertib, cilostazol, cimetidine, ciprofloxacin, chlorzoxazone, clotrimazole, cranberry juice, cyclosporine, daridorexant, delavirdine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, larotrectinib, lacidipine, lapatinib, lazertinib, leflunomide, levamlodipine, linagliptin, lurasidone, maribavir, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, sitaxsentan, skullcap, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, vonoprazan, and zileuton.(1-3) |
JUXTAPID |
| Raltegravir/Aluminum & Magnesium Antacids & Magnesium Supplements SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Aluminum and/or magnesium containing antacids may alter raltegravir absorption by altering gastric pH. Magnesium antacids and supplements may bind to raltegravir in the GI tract, preventing its absorption.(1) CLINICAL EFFECTS: Aluminum and/or magnesium containing antacids and magnesium supplements may reduce levels and clinical effectiveness of raltegravir.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Concurrent use of any formulation of raltegravir and aluminum and/or magnesium antacids is not recommended. Instruct patients not to use aluminum and/or magnesium containing antacids or magnesium supplements. Calcium carbonate may be used in place of aluminum and/or magnesium containing antacids in patients receiving raltegravir chewable tablets, oral suspension, or 400 mg tablets. Calcium carbonate is not recommended for patients receiving one daily raltegravir (600 mg tablets).(1) DISCUSSION: Simultaneous administration of aluminum and magnesium hydroxide (20 ml) with raltegravir (400 mg BID) decreased raltegravir maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) by 44%, 49%, and 63%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours before raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 51%, 51%, and 56%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 22%, 30%, and 57%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 4 hours before after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 22%, 19%, and 60%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 4 hours after after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 30%, 32%, and 62%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 6 hours before after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 10%, 13%, and 50%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 6 hours after after raltegravir (400 mg BID) decreased raltegravir Cmax, AUC, and Cmin by 10%, 11%, and 49%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 12 hours after after raltegravir (1200 mg single dose) decreased raltegravir Cmax, AUC, and Cmin by 14%, 14%, and 58%, respectively.(1,2) Data from in vitro(3) and in vivo simulations(4) suggest that magnesium's effect on raltegravir may involve chelation as well as changes in pH. |
ISENTRESS, ISENTRESS HD |
| Colchicine (for Gout & FMF)/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may affect the transport of colchicine, a P-gp substrate.(1,2) CLINICAL EFFECTS: Concurrent use of a P-gp inhibitor may result in elevated levels of and toxicity from colchicine. Symptoms of colchicine toxicity include abdominal pain; nausea or vomiting; severe diarrhea; muscle weakness or pain; numbness or tingling in the fingers or toes; myelosuppression; feeling weak or tired; increased infections; and pale or gray color of the lips, tongue, or palms of hands.(1,2) PREDISPOSING FACTORS: This interaction is expected to be more severe in patients with renal and/or hepatic impairment(1,2) and in patients who receive concurrent therapy. PATIENT MANAGEMENT: The concurrent use of colchicine with P-gp inhibitors is contraindicated in patients with renal or hepatic impairment.(1-3) Avoid concurrent use in other patients, if possible.(3) In patients without renal or hepatic impairment who are currently taking or have taken a P-gp inhibitor in the previous 14 days, the dosage of colchicine should be reduced. For gout flares, the recommended dosage is 0.6 mg (1 tablet) for one dose. This dose should be repeated no earlier than in 3 days.(1,2) For gout prophylaxis, if the original dosage was 0.6 mg twice daily, use 0.3 mg daily. If the original dosage was 0.6 mg daily, use 0.3 mg every other day.(3-12) For Familial Mediterranean fever (FMF), the recommended maximum daily dose is 0.6 mg (may be given as 0.3 mg twice a day).(1,2) Patients should be instructed to immediately report any signs of colchicine toxicity, such as abdominal pain, nausea/significant diarrhea, vomiting; muscle weakness/pain; numbness/tingling in fingers/toes; unusual bleeding or bruising, infections, weakness/tiredness, or pale/gray color of the lips/tongue/palms of hands. DISCUSSION: There are several reports of colchicine toxicity(4-6) and death(7,8) following the addition of clarithromycin to therapy. In a retrospective review of 116 patients who received clarithromycin and colchicine during the same hospitalization, 10.2% (9/88) of patients who received simultaneous therapy died, compared to 3.6% (1/28) of patients who received sequential therapy.(9) An FDA review of 117 colchicine-related deaths that were not attributable to overdose found that 60 deaths (51%) involved concurrent use of clarithromycin.(2) There is one case report of colchicine toxicity with concurrent erythromycin.(10) In a study in 20 subjects, pretreatment with diltiazem (240 mg daily for 7 days) increased the maximum concentration (Cmax) and area-under-curve (AUC) of a single dose of colchicine (0.6 mg) by 44.2% (range -46.6% to 318.3%) and by 93.4% (range -30.2% to 338.6%), respectively.(1) In a study in 24 subjects, pretreatment with verapamil (240 mg twice daily for 7 days) increased the Cmax and AUC of a single dose of colchicine (0.6 mg) by 40.1% (range -47.1% to 149.5%) and by 103.3% (range -9.8% to 217.2%), respectively.(1) Colchicine toxicity has been reported with concurrent use of CYP3A4 and P-gp inhibitors such as clarithromycin, cyclosporine, diltiazem, erythromycin, and verapamil.(1,2) P-gp inhibitors include abrocitinib, amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, erythromycin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, schisandra, selpercatinib, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vimseltinib, and voclosporin.(1,11,12) |
COLCHICINE, COLCRYS, GLOPERBA, MITIGARE, PROBENECID-COLCHICINE |
| Dalfampridine/Cimetidine; Dolutegravir SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Cimetidine and dolutegravir inhibit the organic cation transporter 2 (OCT2). Dalfampridine is eliminated mainly via the kidneys with active renal secretion by OCT2.(1-3) CLINICAL EFFECTS: The concurrent administration of dalfampridine with an inhibitor of OCT2 may result in elevated levels of dalfampridine and signs of toxicity. Elevated levels of dalfampridine may increase the risk of seizures.(1,2) PREDISPOSING FACTORS: Renal impairment. PATIENT MANAGEMENT: The US manufacturer of dalfampridine states that the potential benefits of taking OCT2 inhibitors concurrently with dalfampridine should be considered against the risk of seizures. If concurrent use is warranted, carefully monitor patients for adverse effects. Permanently discontinue dalfampridine in patients who have a seizure while on treatment.(1) The UK and Canadian manufacturers of dalfampridine states that concurrent use of dalfampridine and OCT2 inhibitors is contraindicated.(4,5) DISCUSSION: In a single dose clinical study in 23 healthy volunteers, the combined use of cimetidine (400 mg every 6 hours) increased the area-under-curve (AUC) of cimetidine approximately 25% due to a reduction in the clearance of dalfampridine.(1) |
4-AMINOPYRIDINE, AMPYRA, DALFAMPRIDINE, DALFAMPRIDINE ER |
| Dasatinib; Pazopanib/H2 Antagonists SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The solubility of dasatinib(1) and pazopanib(2) is pH dependent. Changes in gastric pH from H2 antagonists may decrease the absorption of dasatinib(1) and pazopanib.(2) CLINICAL EFFECTS: Use of H2 antagonists may result in decreased levels and effectiveness of dasatinib(1) and pazopanib.(2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid the use of H2-antagonists and proton pump inhibitors (PPIs) in patients receiving treatment with dasatinib(1) or pazopanib.(2) Consider the use of short-acting antacids in these patients.(1) If antacids are used, separate the administration times by at least two hours for dasatinib(1) and several hours for pazopanib.(2) The manufacturer of Phyrago states that it can be administered with gastric acid reducing agents. Administration times should be separated with antacids.(3) DISCUSSION: In a study in 24 healthy subjects, administration of a single dose of dasatinib (50 mg) 10 hours after famotidine decreased dasatinib area-under-curve (AUC) and maximum concentration (Cmax) by 61% and 63%, respectively.(1) In a study in 14 healthy subjects, administration of a single dose of dasatinib (100 mg) 22 hours after omeprazole (40 mg at steady state) decreased dasatinib AUC and Cmax by 43% and 42%, respectively.(1) In a study in 24 healthy subjects, simultaneous administration of dasatinib (50 mg) with aluminum hydroxide/magnesium hydroxide (30 ml) decreased dasatinib AUC and Cmax by 55% and 58%, respectively. In the same subjects, administration of the antacid 2 hours before dasatinib decreased dasatinib Cmax by 26%, but had no effect on dasatinib AUC.(1) In a study in 13 patients, esomeprazole (40 mg daily for 5 days) decreased the Cmax and AUC of pazopanib (400 mg daily) by 42% and 40%, respectively, when compared to the administration of pazopanib alone.(2) Phyrago is not sensitive to increased gastric pH due to its polymer formulation. No clinically significant pharmacokinetic changes were seen with concurrent administration of Phyrago with omeprazole (proton pump inhibitor) or famotidine (H2 receptor antagonist).(3) |
DASATINIB, PAZOPANIB HCL, SPRYCEL, VOTRIENT |
| Eliglustat/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of eliglustat. If the patient is also taking an inhibitor of CYP2D6, eliglustat metabolism can be further inhibited.(1) CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of eliglustat, including prolongation of the PR, QTc, and/or QRS intervals, which may result in life-threatening cardiac arrhythmias.(1) PREDISPOSING FACTORS: If the patient is also taking an inhibitor of CYP2D6, is a poor metabolizer of CYP2D6, and/or has hepatic impairment, eliglustat metabolism can be further inhibited.(1) The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The concurrent use of eliglustat with weak inhibitors of CYP3A4 in poor metabolizers of CYP2D6 should be avoided.(1) The dosage of eliglustat with weak inhibitors of CYP3A4 in extensive metabolizers of CYP2D6 with mild (Child-Pugh Class A) hepatic impairment should be limited to 84 mg daily.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Ketoconazole (400 mg daily), a strong inhibitor of CYP3A4, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 4-fold and 4.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested ketoconazole would increase eliglustat Cmax and AUC by 4.4-fold and 5.4-fold, respectively, in intermediate metabolizers. PKPB models suggested ketoconazole may increase the Cmax and AUC of eliglustat (84 mg daily) by 4.3-fold and 6.2-fold, respectively, in poor metabolizers.(1) PKPB models suggested fluconazole, a moderate inhibitor of CYP3A4, would increase eliglustat Cmax and AUC by 2.8-fold and 3.2-fold, respectively, in extensive metabolizers and by 2.5-fold and 2.9-fold, respectively in intermediate metabolizers. PKPB models suggest that concurrent eliglustat (84 mg BID), paroxetine (a strong inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 16.7-fold and 24.2-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 7.5-fold and 9.8-fold, respectively.(1) PKPB models suggest that concurrent eliglustat (84 mg BID), terbinafine (a moderate inhibitor of CYP2D6), and ketoconazole would increase eliglustat Cmax and AUC by 10.2-fold and 13.6-fold, respectively, in extensive metabolizers. In intermediate metabolizers, eliglustat Cmax and AUC would be expected to increase 4.2-fold and 5-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, and vonoprazan.(3,4) |
CERDELGA |
| Erdafitinib/Serum Phosphate Level-Altering Drugs SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Medications that alter serum phosphate may interfere with interpretation of phosphate levels that are needed to determine initial erdafitinib dose.(1) CLINICAL EFFECTS: Serum phosphate levels that are elevated by concomitant medications may result in an inappropriately low dose and decreased effectiveness of erdafitinib. Serum phosphate levels that are decreased by concomitant medications may result in an inappropriately high dose and increased toxicity from erdafitinib. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of erdafitinib states that agents that alter serum phosphate levels should be avoided before the initial dose increase period for erdafitinib based on serum phosphate levels (days 14 to 21).(1) DISCUSSION: Concomitant administration of serum phosphate level-altering agents during the initial dose increase period of erdafitinib based on serum phosphate levels (days 14 to 21) may interfere with serum phospate levels and lead to incorrect dosing of erdafitinib.(1) Agents that may alter serum phosphate levels linked to this monograph include: aluminum carbonate, aluminum hydroxide, calcium acetate, calcium carbonate, calcium citrate, cod liver oil, ferric citrate, lanthanum, magnesium carbonate, magnesium hydroxide, potassium phosphate, sevelamer, sodium phosphate, sucroferric oxyhydroxide, tenapanor, and vitamin D.(1) |
BALVERSA |
| Secretin/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: H2 antagonists and proton pump inhibitors (PPIs) may result in an incorrect secretin stimulation test result.(1) CLINICAL EFFECTS: Concurrent use of H2 antagonists and proton pump inhibitors (PPIs) may impact the accuracy of the secretin stimulation test.(1) PREDISPOSING FACTORS: Patients with alcoholic or other liver disease may be hyperresponsive to stimulation with a secretin stimulation test, masking the presence of coexisting pancreatic disease. Consider additional testing and clinical assessment for diagnosis.(1) PATIENT MANAGEMENT: The US manufacturer of human secretin states concurrent use of H2 antagonists and proton pump inhibitors (PPIs) at the time of stimulation testing may cause the patient to be hyperresponsive to secretin stimulation and suggest false gastrinoma results. The manufacturer recommends discontinuing H2 antagonists at least 2 days prior to testing. The US manufacturer of vonoprazan recommends stopping vonoprazan at least 4 weeks prior to testing.(2-3) Consult prescribing information for PPIs before administering prior to a secretin stimulation test.(1) DISCUSSION: Concurrent use of H2 antagonists and proton pump inhibitors (PPIs) may impact the accuracy of the secretin stimulation test.(1) |
CHIRHOSTIM |
| Oral Lefamulin/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of P-glycoprotein (P-gp) may increase the absorption of lefamulin.(1) Oral lefamulin tablets may inhibit the metabolism of P-gp inhibitors that are also sensitive CYP3A4 substrates (i.e., asunaprevir, felodipine, ivacaftor, and neratinib).(1-3) CLINICAL EFFECTS: The concurrent administration of lefamulin with an inhibitor of P-gp may result in elevated levels of lefamulin and signs of toxicity, such as QT prolongation. Coadministration of oral lefamulin with agents that are also sensitive CYP3A4 substrates (i.e., asunaprevir, felodipine, ivacaftor, and neratinib) may result in elevated levels and toxicities of the sensitive CYP3A4 substrate. PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: The US manufacturer of lefamulin states that oral lefamulin tablet coadministration with P-gp inhibitors should be avoided.(1) If concomitant therapy with a P-gp inhibitor is necessary, monitor patients closely for prolongation of the QT interval. Obtain serum calcium, magnesium, and potassium levels and monitor ECG at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. Concomitant use of asunaprevir, felodipine, ivacaftor, or neratinib requires close monitoring for adverse effects of these drugs.(1) The manufacturer of venetoclax states that if concurrent use with a P-gp substrate cannot be avoided, take lefamulin at least 6 hours before venetoclax.(5) DISCUSSION: Coadministration of ketoconazole (a strong CYP3A4 and P-gp inhibitor) with lefamulin tablets increased lefamulin area-under-the-curve (AUC) and maximum concentration (Cmax) by 165% and 58%.(1) In a study, oral lefamulin tablets administered concomitantly with and at 2 or 4 hours before oral midazolam (a CYP3A4 substrate) increased the area-under-curve (AUC) and maximum concentration (Cmax) of midazolam by 200% and 100%, respectively. No clinically significant effect on midazolam pharmacokinetics was observed when co-administered with lefamulin injection.(1) P-gp inhibitors include: asunaprevir, belumosudil, capmatinib, carvedilol, cimetidine, danicopan, daridorexant, diosmin, flibanserin, fluvoxamine, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, ivacaftor, ledipasvir, neratinib, pirtobrutinib, propafenone, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, valbenazine, venetoclax, vimseltinib, and voclosporin.(1-3) |
XENLETA |
| Clozapine/Anticholinergics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Clozapine has potent anticholinergic properties and inhibits serotonin receptors, including 5-HT3.(1-4) Both of these properties may cause inhibition of gastrointestinal (GI) smooth muscle contraction, resulting in decreased peristalsis.(3,4) These effects may be compounded by concurrent use of anticholinergic agents.(1-6) CLINICAL EFFECTS: Concurrent use of clozapine with other anticholinergic agents may increase the risk of constipation (common) and serious bowel complications (uncommon), including complete bowel obstruction, fecal impaction, paralytic ileus and intestinal ischemia or infarction.(1-6) PREDISPOSING FACTORS: The risk for serious bowel complications is higher with increasing age, higher frequency of constipation, and in patients on higher doses of clozapine or multiple anticholinergic agents.(1,5) PATIENT MANAGEMENT: Avoid the use of other anticholinergic agents with clozapine.(1-6) If concurrent use is necessary, evaluate the patient's bowel function regularly. Monitor for symptoms of constipation and GI hypomotility, including having bowel movements less than three times weekly or less than usual, difficulty having a bowel movement or passing gas, nausea, vomiting, and abdominal pain or distention.(2) Consider a prophylactic laxative in those with a history of constipation or bowel obstruction.(2) Review patient medication list for other anticholinergic agents. When possible, decrease the dosage or number of prescribed anticholinergic agents, particularly in the elderly. Counsel the patient about the importance of maintaining adequate hydration. Encourage regular exercise and eating a high-fiber diet.(2) DISCUSSION: In a prospective cohort study of 26,720 schizophrenic patients in the Danish Central Psychiatric Research Registry, the odds ratio (OR) for ileus was 1.99 with clozapine and 1.48 with anticholinergics. The OR for fatal ileus was 6.73 with clozapine and 5.88 with anticholinergics. Use of anticholinergics with 1st generation antipsychotics (FGA) increased the risk of ileus compare to FGA alone, but this analysis was not done with clozapine.(5) A retrospective cohort study of 24,970 schizophrenic patients from the Taiwanese National Health Insurance Research Database found that the hazard ratio (HR) for clozapine-induced constipation increased from 1.64 when clozapine is used alone, to 2.15 when used concomitantly with anticholinergics. However, there was no significant difference in the HR for ileus when clozapine is used with and without anticholinergics (1.95 and 2.02, respectively).(6) In the French Pharmacovigilance Database, 7 of 38 cases of antipsychotic-associated ischemic colitis or intestinal necrosis involved clozapine, and 5 of these cases involved use of concomitant anticholinergic agents. Three patients died, one of whom was on concomitant anticholinergics.(3) In a case series, 4 of 9 cases of fatal clozapine-associated GI dysfunction involved concurrent anticholinergic agents.(4) |
CLOZAPINE, CLOZAPINE ODT, CLOZARIL, VERSACLOZ |
| Selected Cephalosporins/Long Acting Antacids; H2s;PPIs SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Absorption of oral cefpodoxime or cefuroxime may be reduced in patients receiving concomitant treatment with acid reducing agents.(1-5) CLINICAL EFFECTS: Antibiotic efficacy against organisms with a high minimum inhibitory concentration (MIC) to cefpodoxime or cefuroxime could be decreased. PREDISPOSING FACTORS: Taking cefpodoxime or cefuroxime on an empty stomach magnifies this effect. PATIENT MANAGEMENT: If possible, avoid the use of H2 antagonists and proton pump inhibitors(PPIs) in patients taking cefpodoxime or cefuroxime. If concurrent therapy is needed with antacids, H2 antagonists, or PPIs, administer cefpodoxime or cefuroxime after eating to maximize oral absorption. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: In a study of ten subjects, administration of cefpodoxime after single dose famotidine 40 mg decreased both maximum concentration (Cmax) and area-under-curve (AUC) by approximately 40 percent compared with administration of cefpodoxime on an empty stomach.(3) In a study of 17 subjects, administration of cefpodoxime after single dose ranitidine 150 mg decreased Cmax and AUC by approximately 40 percent compared with administration of cefpodoxime on an empty stomach.(4) In a study performed prior to the introduction of PPIs, administration of ranitidine 300 mg and sodium bicarbonate followed by cefuroxime taken on a empty stomach lowered both Cmax and AUC of cefuroxime by approximately 40 per cent compared with administration of cefuroxime alone on an empty stomach. Postprandial administration of cefuroxime in subjects taking ranitidine was similar to that of subjects taking cefuroxime on an empty stomach.(5) |
CEFPODOXIME PROXETIL, CEFUROXIME |
| Selected MATE Substrates/MATE Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of the Multidrug and Toxin Extrusion (MATE) renal protein transporters in the kidneys may inhibit the transport of MATE substrates.(1) Acyclovir, cephalexin, and valacyclovir are MATE substrates. CLINICAL EFFECTS: Concurrent use of MATE renal transporter inhibitors may result in increased levels of and toxicity from MATE substrates.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid concurrent use of acyclovir, cephalexin, or valacyclovir with MATE renal transporter inhibitors. If concurrent use cannot be avoided, monitor for toxicity of the MATE substrate and consider dosage reduction of the MATE substrate.(1) DISCUSSION: Based upon in vitro data, risdiplam is expected to produce clinically significant inhibition of MATE1 and MATE2-K transporters at clinically relevant concentrations.(1) Selected MATE substrates linked include: acyclovir, cephalexin, and valacyclovir.(1,2) MATE inhibitors include: cimetidine, pyrimethamine, risdiplam, and vandetanib.(2) |
ACYCLOVIR, ACYCLOVIR SODIUM, ACYCLOVIR SODIUM-0.9% NACL, CEPHALEXIN, VALACYCLOVIR, VALACYCLOVIR HCL, VALTREX, ZOVIRAX |
| Selected Mesalamine/Antacids SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Certain mesalamine formulations (namely Apriso) contain granules with an enteric coating that dissolves at pH 6 and above. Antacids may raise the intragastric pH, resulting in premature release of the drug in the stomach.(1) CLINICAL EFFECTS: Simultaneous administration of certain mesalamine formulations (namely Apriso) with an antacid may result in premature release of mesalamine in the stomach and decreased effectiveness in the intestines and colon.(1-2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of Apriso states that coadministration with antacids should be avoided.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: Dissolution of the enteric coating of mesalamine is pH-dependent. Coadministration of certain mesalamine formulations (namely Apriso) with antacids should be avoided.(1) |
APRISO, MESALAMINE ER |
| Relugolix/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Relugolix is a substrate of the intestinal P-glycoprotein (P-gp) efflux transporter. Inhibitors of P-gp may increase the absorption of relugolix.(1) CLINICAL EFFECTS: The concurrent administration of relugolix with an inhibitor of P-glycoprotein may result in elevated levels of relugolix and adverse effects, including hot flashes, skin flushing, musculoskeletal pain, hyperglycemia, acute renal injury, transaminitis, arrhythmias, and hemorrhage.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of relugolix states that the coadministration of relugolix with P-gp inhibitors should be avoided. If the P-gp inhibitor is to be used short-term, relugolix may be held for up to 2 weeks. If treatment with relugolix is interrupted for longer than 7 days, resume relugolix with a loading dose of 360 mg on the first day, followed by 120 mg once daily.(1) If coadministration with a P-gp inhibitor cannot be avoided, relugolix should be taken at least 6 hours before the P-gp inhibitor. Monitor the patient more frequently for adverse events.(1) DISCUSSION: Coadministration of relugolix with erythromycin (a P-gp and moderate CYP3A4 inhibitor) increased the area-under-curve (AUC) and maximum concentration (Cmax) of relugolix by 6.2-fold. Voriconazole (a strong CYP3A4 inhibitor) did not have a clinically significant effect on the pharmacokinetics of relugolix.(1) P-gp inhibitors linked to this monograph include: amiodarone, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, curcumin, cyclosporine, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, indinavir, itraconazole, ivacaftor, josamycin, ketoconazole, lapatinib, lonafarnib, mavorixafor, mibefradil, mifepristone, neratinib, osimertinib, paroxetine, pirtobrutinib, propafenone, quinidine, quinine, ranolazine, ritonavir, sarecycline, schisandra, selpercatinib, simeprevir, sotorasib, telaprevir, telithromycin, tepotinib, tezacaftor, tucatinib, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vimseltinib, and voclosporin.(2,3) |
MYFEMBREE, ORGOVYX |
| Chloroquine; Hydroxychloroquine/MATE Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Inhibitors of the Multidrug and Toxin Extrusion (MATE) protein transporters in the kidneys may inhibit the renal tubular secretion of chloroquine or hydroxychloroquine via the MATE1 transporter.(1,2) CLINICAL EFFECTS: Concurrent use of MATE inhibitors may result in increased levels of and toxicity from chloroquine or hydroxychloroquine, including irreversible retinopathy, potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP), hypoglycemia, or myopathy.(1,2) PREDISPOSING FACTORS: In general, the risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: The manufacturers of chloroquine and hydroxychloroquine state that concomitant use of MATE inhibitors should be avoided.(1,2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a study of healthy volunteers, cimetidine (400 mg daily for 4 days) decreased the clearance of single-dose chloroquine (300 mg) by 53% and half-life by 49%, compared to subjects not on cimetidine.(4) MATE inhibitors linked to this monograph include: bictegravir, cimetidine, isavuconazole, pyrimethamine, risdiplam, trimethoprim, and tucatinib.(5) |
CHLOROQUINE PHOSPHATE, HYDROXYCHLOROQUINE SULFATE, PLAQUENIL, SOVUNA |
| Eluxadoline/Anticholinergics; Opioids SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Eluxadoline is a mixed mu-opioid and kappa-opioid agonist and delta-opioid antagonist and may alter or slow down gastrointestinal transit.(1) CLINICAL EFFECTS: Constipation related adverse events that sometimes required hospitalization have been reported, including the development of intestinal obstruction, intestinal perforation, and fecal impaction.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid use with other drugs that may cause constipation. If concurrent use is necessary, evaluate the patient's bowel function regularly. Monitor for symptoms of constipation and GI hypomotility, including having bowel movements less than three times weekly or less than usual, difficulty having a bowel movement or passing gas, nausea, vomiting, and abdominal pain or distention.(1) Instruct patients to stop eluxadoline and immediately contact their healthcare provider if they experience severe constipation. Loperamide may be used occasionally for acute management of severe diarrhea, but must be discontinued if constipation develops.(1) DISCUSSION: In phase 3 clinical trials, constipation was the most commonly reported adverse reaction (8%). Approximately 50% of constipation events occurred within the first 2 weeks of treatment while the majority occurred within the first 3 months of therapy. Rates of severe constipation were less than 1% in patients receiving eluxadoline doses of 75 mg and 100 mg.(1) |
VIBERZI |
| Sotorasib/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The aqueous solubility of sotorasib is pH dependent. Higher gastric pH leads to lower solubility which may reduce sotorasib absorption.(1) CLINICAL EFFECTS: Coadministration of proton pump inhibitors (PPIs) or H2 antagonists may reduce the bioavailability of sotorasib, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of sotorasib with proton pump inhibitors, H2 antagonists, and antacids should be avoided. If coadministration with an acid-reducing agent is unavoidable, take sotorasib 4 hours before or 10 hours after a locally acting antacid.(1) The UK manufacturer of sotorasib states if co-administration with an acid-reducing agent (such as a PPI or an H2 antagonist) is required, sotorasib should be taken with an acidic beverage (such as cola). Alternatively, sotorasib should be taken 4 hours before or 10 hours after administration of a local antacid.(2) DISCUSSION: The solubility of sotorasib in the aqueous media decreases over the range pH 1.2 to 6.8 from 1.3 mg/mL to 0.03 mg/mL. In an interaction study, coadministration of repeat doses of omeprazole with a single dose of sotorasib decreased sotorasib maximum concentration (Cmax) by 65% and area-under-curve (AUC) by 57% under fed conditions, and decreased sotorasib Cmax by 57% and AUC by 42% under fasted conditions. Under fasted conditions, co-administration of repeat doses of omeprazole with a single dose of sotorasib and 240ml of an acidic beverage (non-diet cola) decreased sotorasib Cmax by 32% and AUC by 23%. The UK manufacturer of sotorasib states the clinical relevance of the decreased sotorasib exposure when co-administered with omeprazole and cola is unclear and sotorasib efficacy might be reduced.(2) Coadministration of a single dose of famotidine given 10 hours prior to and 2 hours after a single dose of sotorasib under fed conditions decreased sotorasib Cmax by 35% and AUC by 38%.(1) |
LUMAKRAS |
| Methylphenidate XR-ODT/H2 Antagonists;Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The solubility of methylphenidate extended release orally disintegrating tablets (XR-ODT) is pH-dependent. At elevated pH, methylphenidate may be released from the tablets more quickly, resulting in increased absorption.(1) CLINICAL EFFECTS: Coadministration of H2 antagonists or proton pump inhibitors (PPIs) may result in an altered pharmacokinetic profile of methylphenidate XR-ODT, which may change the effectiveness and/or adverse effects of methylphenidate XR-ODT.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of methylphenidate XR-ODT with H2 antagonists or PPIs is not recommended.(1,2) DISCUSSION: In in vitro studies, when media pH was increased from 1.2 to 6.8, percentage release of methylphenidate from the XR-ODT tablet was increased by 67% at 0.5 hours, and by 93% at 2.5 hours. The increased dissolution of methylphenidate at higher pH may result in increased drug absorption and change the concentration-time profile of methylphenidate, which is correlated with pharmacological effect.(1) |
COTEMPLA XR-ODT |
| Doxorubicin/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibition may increase doxorubicin cellular concentration, as well as decrease biliary or renal elimination.(1) CLINICAL EFFECTS: Increased cellular or systemic levels of doxorubicin may result in doxorubicin toxicity, including cardiomyopathy, myelosuppression, or hepatic impairment.(1) PREDISPOSING FACTORS: The interaction magnitude may be greater in patients with impaired renal or hepatic function. PATIENT MANAGEMENT: Avoid the concurrent use of P-gp inhibitors in patients undergoing therapy with doxorubicin.(1) Consider alternatives with no or minimal inhibition. If concurrent therapy is warranted, monitor the patient closely for signs and symptoms of doxorubicin toxicity. DISCUSSION: Doxorubicin is a substrate of P-gp.(1) Clinical studies have identified and evaluated the concurrent use of doxorubicin and P-gp inhibitors as a target to overcome P-gp mediated multidrug resistance.(2,3) P-gp inhibitors linked to this monograph include: amiodarone, asciminib, asunaprevir, azithromycin, belumosudil, capmatinib, cimetidine, cyclosporine, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, dronedarone, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo, ginseng, glecaprevir/pibrentasvir, hydroquinidine, istradefylline, ivacaftor, lapatinib, ledipasvir, mavorixafor, neratinib, osimertinib, paroxetine, pirtobrutinib, propafenone, quercetin, quinidine, quinine, ranolazine, sarecycline, schisandra, selpercatinib, simeprevir, sofosbuvir/velpatasvir/voxilaprevir, sotorasib, tepotinib, tezacaftor, valbenazine, vemurafenib, verapamil, vimseltinib, and voclosporin.(4,5) |
ADRIAMYCIN, CAELYX, DOXIL, DOXORUBICIN HCL, DOXORUBICIN HCL LIPOSOME |
| Levoketoconazole/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The aqueous solubility of levoketoconazole is pH dependent. Higher gastric pH leads to lower solubility. H2-receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) increase gastric pH and may decrease the absorption of levoketoconazole.(1) CLINICAL EFFECTS: Coadministration of H2RAs or PPIs may reduce the bioavailability of levoketoconazole, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of levoketoconazole with PPIs and H2RAs should be avoided.(1) DISCUSSION: Levoketoconazole is very slightly soluble in water but soluble below pH 2. H2RAs and PPIs raise gastric pH and may impair dissolution and absorption of levoketoconazole.(1) |
RECORLEV |
| Mavacamten/Weak CYP2C19 Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Weak CYP2C19 inhibitors may inhibit the metabolism of mavacamten.(1-3) CLINICAL EFFECTS: Concurrent use of weak CYP2C19 inhibitors increases plasma exposure of mavacamten which may increase the incidence and severity of adverse reactions of mavacamten.(1-3) PREDISPOSING FACTORS: CYP2C19 rapid and ultrarapid metabolizers may experience an increased incidence or severity of adverse effects.(1-3) PATIENT MANAGEMENT: The US manufacturer of mavacamten recommends to initiate mavacamten at the recommended starting dosage of 5 mg orally once daily in patients who are on stable therapy with a weak CYP2C19 inhibitor. Reduce dose by one level (i.e., 15 to 10 mg, 10 to 5 mg, or 5 to 2.5 mg) in patients who are on mavacamten treatment and intend to initiate a weak CYP2C19 inhibitor. Schedule clinical and an echocardiographic assessment 4 weeks after inhibitor initiation, and do not up-titrate mavacamten until 12 weeks after inhibitor initiation.(1) Avoid initiation of concomitant weak CYP2C19 inhibitors in patients who are on stable treatment with 2.5 mg of mavacamten because a lower dose is not available.(1) For short-term use (e.g. 1 week), interrupt mavacamten therapy for the duration of the weak CYP2C19 inhibitor. After therapy with the weak CYP2C19 inhibitor is discontinued, mavacamten may be reinitiated at the previous dose immediately upon discontinuation.(1) The Canadian manufacturer of mavacamten recommends additional monitoring when concurrent use of weak CYP2C19 inhibitors is warranted. Adjust the dose of mavacamten based on clinical assessment.(2) The UK manufacturer of mavacamten states no dose adjustment is necessary with weak CYP2C19 inhibitors. Monitor left ventricular ejection fraction (LVEF) in 4 weeks then resume usual monitoring schedule.(3) DISCUSSION: Concomitant use of mavacamten (15 mg) with omeprazole (20 mg), a weak CYP2C19 inhibitor, once daily increased mavacamten area-under-curve (AUC) by 48% with no effect on maximum concentration (Cmax) in healthy CYP2C19 normal metabolizers and rapid metabolizers.(1) Weak CYP2C19 inhibitors include: armodafinil, cimetidine, enasidenib, eslicarbazepine, felbamate, givosiran, isoniazid, obeticholic acid, osilodrostat, piperine, rucaparib, tecovirimat.(4,5) |
CAMZYOS |
| Sparsentan/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The aqueous solubility of sparsentan is pH dependent. Higher gastric pH leads to lower solubility. H2-receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) increase gastric pH and may decrease the absorption of sparsentan.(1) CLINICAL EFFECTS: Coadministration of H2RAs or PPIs may reduce the bioavailability of sparsentan, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of sparsentan with PPIs and H2RAs should be avoided.(1) DISCUSSION: Sparsentan is practically insoluble in water but has intrinsic solubility of 1.48 mg/mL and 0.055 mg/mL below pH 1.2 and 6.8, respectively. H2RAs and PPIs raise gastric pH and may impair dissolution and absorption of sparsentan.(1) |
FILSPARI |
| Nirogacestat/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The aqueous solubility of nirogacestat is pH dependent. Higher gastric pH leads to lower solubility which may reduce nirogacestat absorption.(1) CLINICAL EFFECTS: Coadministration of proton pump inhibitors (PPIs) or H2 antagonists may reduce the bioavailability of nirogacestat, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of nirogacestat with proton pump inhibitors, H2 antagonists, and antacids should be avoided. If coadministration with an acid-reducing agent is unavoidable, take nirogacestat 2 hours before or 2 hours after a locally acting antacid.(1) DISCUSSION: The solubility of nirogacestat is poor at a pH >= 6.(1) Concomitant use of proton pump inhibitors, H2 antagonists, or antacids are expected to reduce concentrations of nirogacestat.(1) |
OGSIVEO |
| Vincristine/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibitors may inhibit cellular efflux of vincristine.(1) CLINICAL EFFECTS: Concurrent administration of a P-gp inhibitor may result in elevated levels of and toxicity from vincristine including myelosuppression, neurologic toxicity, tumor lysis syndrome, hepatotoxicity, constipation, or bowel obstruction.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid the use of P-gp inhibitors in patients undergoing therapy with vincristine.(1) Consider alternatives with no or minimal P-gp inhibition. The manufacturer of vincristine states that concomitant use of P-gp inhibitors should be avoided.(1) The manufacturer of lopinavir/ritonavir states that patients who develop significant hematological or gastrointestinal toxicity on concomitant vincristine should temporarily hold lopinavir/ritonavir, or use alternative medications that do not inhibit CYP3A4 or P-gp.(2) DISCUSSION: Vincristine is a substrate of P-gp. Inhibitors of P-gp may increase toxicity of vincristine.(1) There are several case reports of neurotoxicity with concurrent administration of vincristine and itraconazole.(3-5) There is a case report of neurotoxicity with concurrent administration of lopinavir-ritonavir with vincristine.(6) In a prospective study in 22 children receiving various chemotherapy with prophylactic itraconazole oral solution (0.5 ml/kg per day), two children receiving vincristine developed non-alcoholic steatohepatitis (NASH) and one child developed syndrome of inappropriate anti-diuretic hormone secretion (SIADH).(7) Strong inhibitors of P-gp linked to this monograph include: abrocitinib, amiodarone, Asian ginseng (Panax ginseng), asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, diltiazem, diosmin, dronedarone, elagolix, eliglustat, erythromycin, flibanserin, fluvoxamine, fostamatinib, ginkgo biloba, glecaprevir and pibrentasvir, isavuconazonium, ivacaftor, lapatinib, mavorixafor, milk thistle (Silybum marianum), neratinib, osimertinib, pirtobrutinib, propafenone, quercetin, quinidine, ranolazine, rolapitant, Schisandra chinensis, selpercatinib, sofosbuvir, sotorasib, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, venetoclax, verapamil, vilazodone, vimseltinib, and voclosporin.(8,9) |
VINCASAR PFS, VINCRISTINE SULFATE |
| Glucagon (Diagnostic)/Anticholinergics SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Glucagon and anticholinergic agents may have additive effects on inhibition of gastrointestinal motility.(1) CLINICAL EFFECTS: Concurrent use of glucagon with anticholinergic agents may increase the risk of gastrointestinal hypomotility, including constipation and bowel complications.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Concurrent use of glucagon as a diagnotic aid is not recommended with the use of anticholinergic agents.(1) If concurrent use is necessary, evaluate the patient's bowel function. Monitor for symptoms of constipation and gastrointestinal hypomotility. DISCUSSION: Both glucagon and anticholinergic agents may have additive effects on inhibition of gastrointestinal motility and increase the risk of gastrointestinal adverse effects.(1) |
GLUCAGON HCL |
| Ensartinib/Selected P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: Ensartinib is a P-glycoprotein (P-gp) substrate. P-gp inhibitors may increase the levels of ensartinib.(1) CLINICAL EFFECTS: The concurrent administration of a P-glycoprotein (P-gp) inhibitor may result in elevated levels of and toxicity from ensartinib.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of ensartinib states that concurrent use of P-glycoprotein (P-gp) inhibitors should be avoided.(1) DISCUSSION: Ensartinib is a substrate of P-gp. Inhibitors of P-gp may increase toxicity of ensartinib.(1) Inhibitors of P-gp linked to this monograph include: abrocitinib, amiodarone, Asian ginseng (Panax ginseng), asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, cyclosporine, danicopan, daridorexant, diosmin, eliglustat, flibanserin, fostamatinib, ginkgo biloba, glecaprevir and pibrentasvir, hydroquinidine, ivacaftor, lapatinib, mavorixafor, milk thistle (Silybum marianum), neratinib, osimertinib, propafenone, quercetin, quinidine, ranolazine, rolapitant, silibinin, silymarin, sotagliflozin, tepotinib, tezacaftor, valbenazine, velpatasvir, vemurafenib, venetoclax, vilazodone, vimseltinib, and voclosporin.(2,3) |
ENSACOVE |
| Defactinib/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The aqueous solubility of defactinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce defactinib absorption.(1) CLINICAL EFFECTS: Coadministration of H2 antagonists or proton pump inhibitors (PPIs) may reduce the bioavailability of defactinib, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of defactinib states that concurrent use with H2 antagonists or proton pump inhibitors should be avoided.(1) If concurrent use with an acid-reducing agent cannot be avoided, administer defactinib 2 hours before or 2 hours after the administration of a locally acting antacid.(1) DISCUSSION: In an interaction study, defactinib area-under-the-curve (AUC) decreased by 79% and maximum concentration (Cmax) decreased by 85% following concomitant use of multiple doses of omeprazole 40 mg daily. The AUC and Cmax of N-desmethyl amide (M4), a major metabolite of defactinib, decreased by 83% and 88%, respectively.(1) |
AVMAPKI-FAKZYNJA, FAKZYNJA |
| Taletrectinib/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 2-Severe Interaction: Action is required to reduce the risk of severe adverse interaction. MECHANISM OF ACTION: The aqueous solubility of taletrectinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce taletrectinib absorption.(1) CLINICAL EFFECTS: Coadministration of H2 antagonists or proton pump inhibitors (PPIs) may reduce the bioavailability of taletrectinib, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of taletrectinib states that concurrent use with H2 antagonists or proton pump inhibitors should be avoided.(1) If concurrent use with an acid-reducing agent cannot be avoided, administer taletrectinib 2 hours before or 2 hours after the administration of a locally acting antacid.(1) DISCUSSION: In an interaction study, taletrectinib area-under-the-curve (AUC) decreased by 40% and maximum concentration (Cmax) decreased by 65% following concomitant use of omeprazole 40 mg daily.(1) |
IBTROZI |
There are 87 moderate interactions.
The clinician should assess the patient’s characteristics and take action as needed. Actions required for moderate interactions include, but are not limited to, discontinuing one or both agents, adjusting dosage, altering administration.
| Drug Interaction | Drug Names |
|---|---|
| Cimetidine/Procainamide SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Renal clearance of procainamide and N-acetylprocainamide are reduced by cimetidine. CLINICAL EFFECTS: Enhanced procainamide and N-acetylprocainamide response may occur in the presence of cimetidine therapy. Toxic levels may occur. PREDISPOSING FACTORS: Renal impairment and older age. PATIENT MANAGEMENT: Monitor patient for signs and symptoms of procainamide toxicity. Procainamide and NAPA levels should be checked. Lower the dosage of procainamide as needed. Elderly patients and those with impaired renal function are especially at risk. Since other H-2 antagonists (e.g., ranitidine, famotidine) do not appear to interact, substituting cimetidine with one of these agents may be desirable. However, if a patient is already receiving this combination and is not experiencing adverse effects, substitution is probably not necessary. DISCUSSION: Available data are limited but indicate that increases in procainamide serum concentrations are lower with ranitidine than with cimetidine. Famotidine does not appear to change procainamide concentrations. Caution is warranted due to procainamide's narrow therapeutic margin of safety. Signs and symptoms of procainamide toxicity include widening of the QRS complex, tachycardia, intraventricular conduction delay, hypotension, oliguria, lethargy, confusion, nausea and vomiting. |
PROCAINAMIDE HCL |
| Lidocaine/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine reduces the hepatic clearance of lidocaine. Changes in hepatic blood flow may contribute. CLINICAL EFFECTS: Increased serum lidocaine levels with enhanced therapeutic and toxic response. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Patients receiving this combination should be monitored for signs of lidocaine toxicity. The dosage of lidocaine should be adjusted based on serum lidocaine levels and patient response. Since other H-2 antagonists (e.g., ranitidine, famotidine) do not appear to interact, substituting cimetidine with one of these agents may be desirable. However, if a patient is already receiving this combination and is not experiencing adverse effects, substitution is probably not necessary. DISCUSSION: This interaction is likely to occur. |
LIDOCAINE, LIDOCAINE HCL, LIDOCAINE HCL IN 5% DEXTROSE |
| Quinidine/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine, a CYP3A4 inhibitor, may inhibit the metabolism of quinidine. CLINICAL EFFECTS: Potentiation of quinidine effects by cimetidine with possible quinidine toxicity, including QT prolongation and potentially life-threatening cardiac arrhythmias, including torsades de pointes. PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(7) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(7) PATIENT MANAGEMENT: If both drugs are administered, adjust the quinidine dose as needed based on serum quinidine levels, cardiac function, and patient response. Since other H-2 antagonists (e.g., ranitidine, famotidine) do not appear to interact, substituting cimetidine with one of these agents may be desirable. Ventricular arrhythmia has been reported during concurrent use of ranitidine and quinidine. However, if a patient is already receiving this combination and is not experiencing adverse effects, substitution is probably not necessary. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: The onset and reversal of the interaction may occur within 48 hours of starting or stopping cimetidine in a patient receiving quinidine. Signs and symptoms of quinidine toxicity include nausea, vomiting and diarrhea, headache, tinnitus, vertigo and confusion. Electrocardiogram changes, including prolongation of the QT and QRS intervals may also occur. |
NUEDEXTA, QUINIDINE GLUCONATE, QUINIDINE SULFATE |
| Tetracyclines/Divalent & Trivalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Di- and trivalent cations may form chelation complexes with tetracyclines, preventing their absorption.(1,2) CLINICAL EFFECTS: Simultaneous administration of di- or trivalent cations may result in decreased levels of and therapeutics effects from tetracyclines. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Administer tetracyclines at least two hours before or after the di- or trivalent cations. When used for the treatment of H. pylori infection, tetracyclines and bismuth should be given simultaneously. The US manufacturer of omadacycline states to fast for at least four hours, administer omadacycline, and then wait four hours before taking di- or trivalent cations.(21) DISCUSSION: Concurrent administration of aluminum hydroxide or divalent cations (such as calcium, magnesium, or zinc) has been shown to significantly decrease the gastrointestinal absorption of tetracycline.(3-5) Concurrent administration of tetracycline and magnesium-aluminum hydroxide gel has been shown to decrease the tetracycline area-under-curve (AUC) by 90%.(6) Magnesium-aluminum silicate has been shown to decrease the AUC of tetracycline by 27%.(7) Demeclocycline(8,9) methacycline,(10) chlortetracycline,(11) and oxytetracycline(10,12) have been shown to interact with aluminum hydroxide and/or dairy products. Doxycycline has been reported to interact with aluminum hydroxide gel.(13) Aluminum magnesium hydroxide has been shown to decrease doxycycline absorption by 84%.(14) Minocycline absorption has been shown to be impaired by aluminum, calcium, and magnesium.(15) Bismuth subsalicylate has been shown to decrease absorption of doxycycline and tetracycline by 37%(16) and 34%,(17) respectively. Since sucralfate is an aluminum salt of a sulfated disaccharide, it may also prevent absorption of tetracyclines. This complex has been used to provide site-specific delivery of tetracycline to gastric ulcers in the treatment of Helicobacter pylori gastric ulcer disease and may be useful in some indications.(18) Quinapril tablets contain a high percentage of magnesium and have been shown to decrease the absorption of tetracycline by 28-37%.(19) Lanthanum is expected to interact with tetracyclines as well.(20) |
AVIDOXY, AVIDOXY DK, BENZODOX 30, BENZODOX 60, BISMUTH-METRONIDAZOLE-TETRACYC, DEMECLOCYCLINE HCL, DORYX, DORYX MPC, DOXYCYCLINE HYCLATE, DOXYCYCLINE IR-DR, DOXYCYCLINE MONOHYDRATE, EMROSI, MINOCYCLINE ER, MINOCYCLINE HCL, MINOCYCLINE HCL ER, MONDOXYNE NL, MORGIDOX, NUZYRA, ORACEA, OXYTETRACYCLINE HCL, PYLERA, SEYSARA, TARGADOX, TETRACYCLINE HCL, XIMINO |
| Penicillamine, Oral/Polyvalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Penicillamine chelates with polyvalent cations such as aluminum, calcium, iron, magnesium, and zinc in the GI tract reducing the absorption of the penicillamine. CLINICAL EFFECTS: Reduced (to 30% of fasting) bioavailability of penicillamine with decreased pharmacologic response. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: In order to assure systemic absorption and maximal effectiveness from penicillamine, counsel patient to separate penicillamine by at least 1 hour before or 1 hours after any medications or products containing polyvalent cations such as antacids or mineral supplements. Monitor clinical status for decreased effectiveness and adjust the penicillamine dose if necessary. DISCUSSION: Clinical studies with polyvalent cations have not been conducted. Multivitamins with low doses of cations including iron and zinc may decrease penicillamine absorption so insure patient is aware of the risks. |
CUPRIMINE, D-PENAMINE, DEPEN, PENICILLAMINE, PENICILLAMINE(D-) |
| Slt Cation-Donating Antacids/Polystyrene Sulfonate SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Polystyrene sulfonate may bind the cation from the antacid, resulting in increased intestinal absorption of non-neutralized bicarbonate, which may result in systemic alkalosis and decreased potassium binding by polystyrene sulfonate. Intestinal obstruction has occurred with aluminum hydroxide because of concretion. CLINICAL EFFECTS: Simultaneous oral use may result in metabolic alkalosis and a decrease in the potassium lowering effect of polystyrene sulfonate. Intestinal obstruction has been reported with aluminum hydroxide. PREDISPOSING FACTORS: Patients with renal failure may be at a higher risk of systemic alkalosis. PATIENT MANAGEMENT: Consider the use of alternative agents to cation-donating antacids in patients receiving oral polystyrene sulfonate when possible. If concurrent use is required, separate the dosing by several hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: In a study in 11 patients with decreased renal function, the administration of magnesium hydroxide and sodium polystyrene sulfonate produced moderate to moderately severe metabolic alkalosis.(2) There are case reports documenting this affect as well.(3-7) Intestinal obstruction has been reported with aluminum hydroxide and sodium polystyrene sulfonate.(8) If the polystyrene sulfonate is administered rectally, a clinically significant interaction is not likely to occur. |
KIONEX, SODIUM POLYSTYRENE SULFONATE, SPS |
| Hydantoins/Cimetidine; Ranitidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The predominant mechanism appears to be inhibition of hepatic microsomal enzymes resulting in impaired hydantoin metabolism. Cimetidine may inhibit the CYP2C9 and CYP2C19 mediated metabolism of phenytoin and other hydantoins. CLINICAL EFFECTS: Concurrent use of cimetidine or ranitidine may result in elevated levels of and toxicity from the hydantoin. Neutropenia and thrombocytopenia have been reported with concurrent cimetidine and phenytoin. Phenytoin has a narrow therapeutic range. Early symptoms of phenytoin toxicity may include nystagmus, ataxia, dysarthria, tremor, hyperreflexia, lethargy, slurred speech, blurred vision, nausea, and vomiting. Severe toxicity may produce organ dysfunction (e.g. coma, irreversible cerebellar dysfunction and atrophy, hypotension, bradycardia, seizures, and cardiac arrest) and may be fatal.(21) PREDISPOSING FACTORS: Renal impairment, hepatic impairment, or hypoalbuminemia. PATIENT MANAGEMENT: Patient receiving concurrent therapy should be monitored for increased hydantoin levels and effects. A dosage adjustment may be required after initiating or discontinuing cimetidine or ranitidine. Monitor the patient for signs of hydantoin toxicity (e.g. nystagmus, ataxia, dysarthria, tremor, hyperreflexia, lethargy, slurred speech, blurred vision, nausea, and vomiting). Substituting famotidine or nizatidine may be considered in patients experiencing adverse effects from the combination or to avoid the interaction. DISCUSSION: There are several case reports and studies documenting increases in phenytoin levels (50% or greater) during concurrent use of cimetidine (400 mg/day to 2400 mg/day).(1-11) Phenytoin toxicity occurred in some patients. The interaction often occurred in two to ten days after concurrent therapy was initiated. Neutropenia and thrombocytopenia have also been reported during concurrent phenytoin and cimetidine.(12-15) There are three case reports of elevated phenytoin levels during concurrent ranitidine therapy.(16-18) However, in a study, no alterations in phenytoin levels were seen,(19) suggesting the interaction may not occur in all patients. Studies have shown that famotidine(1) and nizatidine(20) do not interact with phenytoin. |
CEREBYX, DILANTIN, DILANTIN-125, FOSPHENYTOIN SODIUM, PHENYTEK, PHENYTOIN, PHENYTOIN SODIUM, PHENYTOIN SODIUM EXTENDED |
| Metoprolol; Propranolol/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine inhibition of CYP2D6 may reduce the metabolism of metoprolol and propranolol. CLINICAL EFFECTS: Concurrent use of cimetidine may result in increased pharmacologic and toxic side effects of metoprolol and propranolol. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Lower dosages of metoprolol and propranolol may be required in patients receiving cimetidine. When initiating cimetidine in a patient maintained on metoprolol or propranolol, observe the patient for increased beta-blocker effects such as lower heart rate and blood pressure. Consider lower starting doses of metoprolol or propranolol in patients receiving cimetidine. A dosage adjustment of the beta-blocker may be necessary when initiating or discontinuing cimetidine. Since other H-2 antagonists (e.g., ranitidine, famotidine) do not appear to interact, substituting cimetidine with one of these agents may be desirable. However, if a patient is already receiving this combination and is not experiencing adverse effects, substitution is probably not necessary. DISCUSSION: Concurrent administration of cimetidine (1G/day to 1.2G/day) and propranolol has resulted in approximately a two-fold increase in propranolol plasma concentrations as well as an increase in its area-under-curve (AUC) and half-life after single (80mg) or multiple (160mg/day) doses. The alterations in propranolol levels were seen within 24 to 48 hours.(1-12) Concurrent administration of cimetidine increased the AUC of metoprolol by 60% to 70%.(11-17) |
HEMANGEOL, INDERAL LA, INDERAL XL, INNOPRAN XL, KAPSPARGO SPRINKLE, LOPRESSOR, METOPROLOL SUCCINATE, METOPROLOL TARTRATE, METOPROLOL-HYDROCHLOROTHIAZIDE, PROPRANOLOL HCL, PROPRANOLOL HCL ER, PROPRANOLOL-HYDROCHLOROTHIAZID, TOPROL XL |
| Itraconazole; Ketoconazole/Agents Affecting Gastric pH SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Antacids, buffers in didanosine products, H2 antagonists, and proton-pump inhibitors increase the stomach pH. Quinapril tablets may contain a high percentage of magnesium. Since some orally administered azole antifungal agents require an acidic medium for optimal absorption, agents may decrease the absorption of azole antifungal agents. CLINICAL EFFECTS: Simultaneous administration of an antacid, buffered didanosine, a H2 antagonist, or a proton-pump inhibitor may result in decreased therapeutic effects of the azole antifungal. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If the concurrent administration of these two agents cannot be avoided, consider administering two capsules of glutamic acid hydrochloride 15 minutes before administering the antifungal and separate the administration times of the antifungal and the agent affecting gastric pH by at least two hours. DISCUSSION: Itraconazole, ketoconazole, and posaconazole require an acidic medium for predictable dissolution and absorption decreases as pH increases and proton pump inhibitors are expected to decrease their absorption.(1-4) In a study in 11 healthy subjects, omeprazole (40 mg daily) decreased the maximum concentration (Cmax) and area-under-curve (AUC) of itraconazole (200 mg single dose) by 66% and 64%, respectively.(5) In a study in 15 healthy subjects, omeprazole (40 mg daily) had no effect on the pharmacokinetics of itraconazole solution.(6) In a study in 9 healthy subjects, omeprazole (60 mg) decreased the AUC of ketoconazole (200 mg single dose) by 83.4% compared to control (ketoconazole alone). Administration of Coca-Cola (240 ml) with ketoconazole and omeprazole raised ketoconazole AUC to 65% of control values.(7) Omeprazole has been shown to have no significant effect on the absorption of fluconazole(8) or voriconazole.(9) Case reports and in-vivo studies have documented significant decreases in ketoconazole levels during concurrent therapy with H-2 antagonists, including cimetidine and ranitidine. Concurrent administration of itraconazole and famotidine resulted in a significant decrease in itraconazole levels, but no significant changes in famotidine levels. An interaction should be expected to occur between both ketoconazole or itraconazole and the other H-2 antagonists.(10-14) In randomized, open-labeled, cross-over study in 12 healthy subjects, simultaneous administration of an antacid decreased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of itraconazole (200 mg) by 66% and 70%, respectively. Time to Cmax (Tmax) increased by 70%.(15) This interaction has also been reported in a case report.(16) In a study in 3 subjects, simultaneous administration of a combination aluminum hydroxide/magnesium hydroxide (30 ml) decreased the AUC of a single dose of ketoconazole (200 mg) by 41%.(172) In a case report, a patient receiving concurrent ketoconazole with aluminum hydroxide, cimetidine, and sodium bicarbonate did not respond to therapy until cimetidine was discontinued and the administration time of aluminum hydroxide and cimetidine was changed to 2 hours after ketoconazole. In a follow-up study in 2 subjects, concurrent cimetidine and sodium hydroxide lowered ketoconazole levels.(18) In a study in 14 subjects, simultaneous administration of aluminum hydroxide/magnesium hydroxide (20 ml, 1800 mg/1200 mg) had no significant effects on fluconazole pharmacokinetics.(3) In a randomized, open-label, cross-over study in 6 subjects, simultaneous administration of itraconazole with buffered didanosine tablets resulted in undetectable levels of itraconazole.(19) In a randomized cross-over study in 12 HIV-positive subjects, administration of buffered didanosine tablets 2 hours after ketoconazole had no effects on ketoconazole levels.(20) In a randomized, cross-over, open-label study in 24 healthy subjects, simultaneous administration of enteric-coated didanosine had no effect on ketoconazole pharmacokinetics.(21) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
ITRACONAZOLE, ITRACONAZOLE MICRONIZED, KETOCONAZOLE, SPORANOX, TOLSURA |
| Cimetidine/Benzodiazepines SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine may decrease the metabolism of Phase I hepatically metabolized benzodiazepines. At doses of 800-2400 mg daily, cimetidine is a weak inhibitor of CYP1A2, CYP2C19, CYP2C9, CYP2D6, and CYP3A4. CLINICAL EFFECTS: Concurrent use may result in increased pharmacologic or toxic effects of certain benzodiazepines. Toxic effects include profound sedation, respiratory depression, coma, and/or death. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Benzodiazepines that do not undergo extensive Phase I metabolism (lorazepam, oxazepam) may be an alternative to interacting benzodiazepines in patients receiving cimetidine or by administering another H-2 antagonist (e.g., ranitidine, famotidine, nizatidine). Cimetidine use at higher doses of 200-400 mg four times daily would have an increased risk of inhibiting the metabolism of benzodiazepines. Lower doses and over-the-counter doses of cimetidine would be expected to have a diminished effect. Consider using alternative H2 antagonists when long-term concurrent therapy with benzodiazepines is indicated. If concurrent use is necessary, monitor patients for unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness. DISCUSSION: Cimetidine increases the half-life and serum concentration and decreases the clearance of benzodiazepines that undergo oxidative metabolism (e.g., alprazolam, bromazepam, diazepam, flurazepam, midazolam, triazolam). In a clinical study, cimetidine 1,200 mg daily decreased the clearance of bromazepam by 50% and increased its half-life from 23 hours to 29 hours.(22) The sedative effects of benzodiazepines have been reported to be increased during concurrent administration of cimetidine. This interaction does not appear to occur with benzodiazepines that undergo glucuronide conjugation. |
CHLORDIAZEPOXIDE HCL, CHLORDIAZEPOXIDE-AMITRIPTYLINE, CHLORDIAZEPOXIDE-CLIDINIUM, CLONAZEPAM, CLORAZEPATE DIPOTASSIUM, DIAZEPAM, DORAL, ESTAZOLAM, FLURAZEPAM HCL, HALCION, KLONOPIN, LIBRAX, MIDAZOLAM, MIDAZOLAM HCL, MIDAZOLAM HCL-0.8% NACL, MIDAZOLAM HCL-0.9% NACL, MIDAZOLAM HCL-D5W, MIDAZOLAM HCL-NACL, MIDAZOLAM-0.9% NACL, MIDAZOLAM-NACL, MKO (MIDAZOLAM-KETAMINE-ONDAN), NAYZILAM, QUAZEPAM, TRIAZOLAM, VALIUM, VALTOCO |
| Carbamazepine/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibition of carbamazepine metabolism by CYP3A4. CLINICAL EFFECTS: The pharmacologic and toxic effects of carbamazepine may be increased. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Monitor serum carbamazepine and observe the patient for signs of carbamazepine toxicity when starting, stopping or altering the dose of cimetidine. Administration of an alternative H-2 antagonist, such as famotidine or ranitidine, may circumvent this interaction. DISCUSSION: Elevated plasma carbamazepine concentrations and toxicity have been reported in patients stabilized on carbamazepine after cimetidine has been started. The effects of this interaction appear to dissipate within one week, at which time carbamazepine returns to the level observed prior to the addition of cimetidine. However, toxicity may still occur as long as these drugs are administered concomitantly. |
CARBAMAZEPINE, CARBAMAZEPINE ER, CARBATROL, EPITOL, EQUETRO, TEGRETOL, TEGRETOL XR |
| Tricyclic Compounds/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine inhibits the hepatic metabolism of tricyclic antidepressants. CLINICAL EFFECTS: The pharmacological and toxic effects of tricyclic antidepressants may be increased. PREDISPOSING FACTORS: The risk of seizures may be increased in patients with a history of head trauma or prior seizure; CNS tumor; severe hepatic cirrhosis; excessive use of alcohol or sedatives; addiction to opiates, cocaine, or stimulants; use of over-the-counter stimulants and anorectics; diabetics treated with oral hypoglycemics or insulin; or with concomitant medications known to lower seizure threshold (antipsychotics, theophylline, systemic steroids). The risk of anticholinergic toxicities including cognitive decline, delirium, falls and fractures is increased in geriatric patients using more than one medicine with anticholinergic properties.(9) PATIENT MANAGEMENT: Observe the patient for an increased or decreased response to tricyclic antidepressant therapy if cimetidine is started or stopped. Adjust the dose of the tricyclic agent accordingly. This interaction can probably be avoided by administration of an H-2 receptor antagonist other than cimetidine (e.g., famotidine, nizatidine, ranitidine). DISCUSSION: Both controlled studies and case reports have demonstrated that concurrent administration of tricyclic antidepressants and cimetidine can result in an increase in plasma tricyclic antidepressant concentrations. Adverse effects have been reported. Similarity between cyclobenzaprine and TCA's warrants consideration of TCA interactions for cyclobenzaprine. |
AMITRIPTYLINE HCL, AMOXAPINE, AMRIX, ANAFRANIL, CHLORDIAZEPOXIDE-AMITRIPTYLINE, CLOMIPRAMINE HCL, CYCLOBENZAPRINE HCL, CYCLOBENZAPRINE HCL ER, CYCLOPAK, CYCLOTENS, DESIPRAMINE HCL, DOXEPIN HCL, FEXMID, IMIPRAMINE HCL, IMIPRAMINE PAMOATE, NORPRAMIN, NORTRIPTYLINE HCL, PAMELOR, PERPHENAZINE-AMITRIPTYLINE, PROTRIPTYLINE HCL, SILENOR, TRIMIPRAMINE MALEATE |
| Selected Calcium Channel Blockers/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine may decrease the metabolism of diltiazem, felodipine, isradipine, nicardipine, nifedipine, nisoldipine, and nitrendipine. CLINICAL EFFECTS: The pharmacological effects of the calcium channel blocker may be increased. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Observe the patient for changes in clinical response to the calcium channel blocker when starting or stopping cimetidine. The dosage of the calcium channel blocker may need to be adjusted. Ideally, suggest an alternative H-2 antagonist such as famotidine, nizatidine, or ranitidine. DISCUSSION: Significant effects have been observed during concurrent administration of nifedipine or felodipine with cimetidine. During combined administration of nifedipine and cimetidine in six healthy volunteers, the area-under-curve (AUC) of nifedipine was increased by 80% compared to nifedipine alone. Increased heart rate and a drop in mean arterial pressure 14 mmHg were also reported. Ranitidine showed only a nonsignificant 25% rise in peak plasma levels of nifedipine and no effects on blood pressure. Similar results were reported in another study where concurrent administration of felodipine and cimetidine resulted in an increase in felodipine AUC and maximum concentration (Cmax) by 50%. Concurrent administration of cimetidine has also been shown to increase the AUC and Cmax of diltiazem by 53% and 58%, respectively. The manufacturers of isradipine and nicardipine recommend carefully monitoring patients receiving concurrent therapy with cimetidine. The manufacturer of isradipine states that concurrent therapy with cimetidine has been shown to increase the AUC of isradipine by 50%. The manufacturer of nifedipine states that careful titration is necessary in patients receiving concurrent therapy. The manufacturers of felodipine and diltiazem state that dosage adjustments may be necessary in patients receiving concurrent therapy. Ranitidine has much less affinity for CYP metabolism than cimetidine and would therefore be expected to have less of an effect on calcium channel blocker metabolism. Studies have shown that nizatidine and famotidine do not inhibit CYP3A4 metabolism. |
CARDENE I.V., CARDIZEM, CARDIZEM CD, CARDIZEM LA, CARTIA XT, DILT-XR, DILTIAZEM 12HR ER, DILTIAZEM 24HR ER, DILTIAZEM 24HR ER (CD), DILTIAZEM 24HR ER (LA), DILTIAZEM 24HR ER (XR), DILTIAZEM HCL, DILTIAZEM HCL-0.7% NACL, DILTIAZEM HCL-0.9% NACL, DILTIAZEM HCL-NACL, DILTIAZEM-D5W, FELODIPINE ER, ISRADIPINE, MATZIM LA, NICARDIPINE HCL, NICARDIPINE HCL-0.9% NACL, NICARDIPINE HCL-NACL, NIFEDIPINE, NIFEDIPINE ER, NIFEDIPINE MICRONIZED, NISOLDIPINE, PROCARDIA XL, SULAR, TIADYLT ER, TIAZAC |
| Etoposide/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: P-glycoprotein (P-gp) inhibition may increase etoposide cellular concentration, decrease biliary or renal elimination, and increase systemic absorption of oral etoposide.(1-4) CLINICAL EFFECTS: Increased cellular or systemic levels of etoposide may result in etoposide toxicity. PREDISPOSING FACTORS: The interaction magnitude may be greater in patients receiving oral etoposide, or with impaired renal or hepatic function. PATIENT MANAGEMENT: Anticipate and monitor for increased hematologic and gastrointestinal toxicities. Adjust or hold etoposide dose when needed. In patients receiving high-dose cyclosporine therapy, etoposide dosages should be reduced by 50%.(1) Monitor for signs of etoposide toxicity. Dosages may need further adjustment. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to etoposide.(5) DISCUSSION: In a study in 16 patients, the administration of etoposide plus cyclosporine increased etoposide area-under-curve (AUC) by 59% and half-life by 73%. Etoposide renal clearance was decreased by 38% and nonrenal clearance was decreased by 52%. White blood cell count nadir was significantly lower during concurrent therapy with cyclosporine and etoposide (1200 mm3) when compared to etoposide alone (2500 mm3). There was also a trend for higher dosages of cyclosporine to exert increased effects on etoposide, although this difference did not reach statistical significance.(1) P-gp inhibitors linked to this monograph are asciminib, asunaprevir, azithromycin, belumosudil, cimetidine, clarithromycin, cyclosporine, daridorexant, danicopan, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, itraconazole, ivacaftor, josamycin, ketoconazole, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, sofosbuvir/velpatasvir/voxilaprevir, tepotinib, tezacaftor, tucatinib, valbenazine, vemurafenib, verapamil, vimseltinib, and voclosporin. |
ETOPOPHOS, ETOPOSIDE |
| Digoxin/Selected Antacids; Kaolin; Sucralfate SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aluminum or magnesium salts may bind digoxin in the gastrointestinal tract, preventing the absorption of digoxin. CLINICAL EFFECTS: Concurrent administration may result in decreased digoxin concentrations and possible decreased clinical effectiveness of digoxin. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Patients receiving concurrent therapy with digoxin and aluminum and/or magnesium hydroxide, magnesium trisilicate, or sucralfate should be monitored for signs of decreased effects of digoxin. Digoxin concentrations should be monitored. The administration of digoxin and aluminum and/or magnesium hydroxide or magnesium trisilicate should be separated by at least one to two hours. The administration of digoxin and sucralfate should be separated by at least two hours. The separation of administration times may not be effective in all patients. The dosage of digoxin may need to be increased by 20% to 40% or the antacid or sucralfate may need to be discontinued. Some vitamin preparations may contain sufficient quantities of magnesium salts with antacid properties to interact as well. DISCUSSION: Sucralfate was shown to decrease the mean digoxin area-under-curve (AUC) by 19% in a study in 12 healthy males. This difference was not seen when digoxin and sucralfate administration was separated by two hours.(1) In a case report, a patient developed intermittent pressure-like chest pain, shortness of breath, and a generalized feeling of fatigue during concurrent administration of digoxin and sucralfate, despite sucralfate administration being separated from digoxin administration by two hours.(2) The simultaneous administration of oral antacids containing magnesium trisilicate, magnesium hydroxide, and aluminum hydroxide or kaolin with digoxin tablets has been shown to decrease the gastrointestinal absorption of digoxin.(3-7) There is some evidence that digoxin capsules may not be affected;(5) however, additional information is needed. |
DIGITEK, DIGOXIN, DIGOXIN MICRONIZED, LANOXIN, LANOXIN PEDIATRIC |
| Quinine/Aluminum and Magnesium Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum and magnesium antacids may delay or decrease the absorption of quinine. CLINICAL EFFECTS: Concurrent use of antacids may result in decreased levels and effectiveness of quinine. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of quinine states that concurrent use with aluminum or magnesium containing antacids should be avoided. Some vitamin preparations may contain sufficient quantities of magnesium salts with antacid properties to interact as well. DISCUSSION: Aluminum and magnesium antacids have been shown to decrease quinine absorption in rats. |
QUALAQUIN, QUININE HCL, QUININE SULFATE |
| Selected Opioid Analgesics/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The metabolism of selected opioid analgesics may be inhibited by cimetidine.(1-15) At doses of 800-2400 mg daily, cimetidine is a moderate inhibitor of CYP3A4 and a weak inhibitor of CYP1A2, CYP2C19, CYP2C9, and CYP2D6.(16) Benzhydrocodone is a prodrug of hydrocodone.(12) CLINICAL EFFECTS: The effect of selected opioid analgesics may be increased including profound sedation, respiratory depression, coma, and/or death. Opioid analgesics have been associated with histamine release and is dependent on dose, route of administration, and rate of administration. Histamine release can cause arteriole dilation and contribute to a profound decrease in systemic blood pressure. The cardiovascular effects of histamine release occurring with the opioid analgesics may be decreased by giving cimetidine concurrently.() PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Cimetidine use at higher doses of 200-400 mg four times daily would have an increased risk of inhibiting the metabolism of opioid analgesics. Lower doses and over-the-counter doses of cimetidine would be expected to have a diminished effect. Consider using alternative H2 antagonists when long-term concurrent therapy with opioid analgesics is indicated. The manufacturer of sufentanil sublingual tablets states that if concomitant use with CYP3A4 inhibitors is necessary, consider use of an alternate agent that allows dose adjustment.(15) Respiratory depression can occur at any time during opioid therapy, especially during therapy initiation and following dosage increases. Consider this risk when using concurrently with agents that may increase opioid drug levels.(17) Monitor the patient for increased adverse effects of the opioid analgesic including respiratory and central nervous system depression, unusual dizziness or lightheadedness, extreme sleepiness, slowed or difficult breathing, or unresponsiveness. Discuss naloxone with all patients when prescribing or renewing an opioid analgesic or medicine to treat opioid use disorder (OUD). Consider prescribing naloxone to patients prescribed medicines to treat OUD or opioid analgesics (such as those taking CNS depressants) who are at increased risk of opioid overdose and when a patient has household members/close contacts at risk for accidental overdose.(18) DISCUSSION: Severe respiratory depression has been reported with the concurrent administration of opioid analgesics and cimetidine. Systemic levels of opioid analgesics metabolized by CYP3A4 may be increased during concurrent use with cimetidine, a CYP3A4 inhibitor.(1-15) In a study of 6 healthy subjects, the effects of ketoconazole (a strong CYP3A4 inhibitor) 400 mg daily for 3 days on alfentanil were studied. The maximum concentration (Cmax) and area-under-curve (AUC) of alfentanil were increased with both sequential and simultaneous dosing of alfentanil with concurrent ketoconazole.(19) In a study of 16 healthy subjects, the effects of ketoconazole 300 mg twice daily for 2 days on fentanyl 5 mcg/kg single dose were examined. Fentanyl AUC was increased by 133% and clearance was reduced to 78%. The metabolism of fentanyl to norfentanyl by CYP3A4 was delayed and partial metabolic clearance decreased by 18% with concurrent ketoconazole.(20) In vitro results of the effects of ketoconazole on hydrocodone confirmed CYP3A4 is responsible for the metabolism of hydrocodone to norhydrocodone.(21) A review discussed the metabolism of hydrocodone by CYP2D6 to O-demethylated hydromorphone and by CYP3A4 to N-demethylated norhydrocodone. CYP3A4 activity is reported as higher in women resulting in higher fractions of the norhydrocodone metabolite in women than in men.(22) A case report of a 46 year old hemodialysis patient was on routine therapy with phenytoin 100 mg three times daily and cimetidine 300 mg three times daily. Four days after starting cimetidine, morphine 15 mg IM every 4 hours was initiated for pain. After the sixth dose of morphine, the patient was apneic with a respiratory rate of 3 breaths/minute and had a grand mal seizure. The patient responded to naloxone 0.4 mg IV single dose with improvement in respiratory rate to 12 breaths/minute. Cimetidine was stopped and phenytoin decreased to 100 mg twice daily with improvement after 80 hours from initial episode. A month later the patient required surgery and was given cimetidine 150 mg twice daily followed by Pantopon 15 mg IM every 3-6 hours postoperatively for pain. The patient again became apneic, confused, and developed muscle twitching which responded to naloxone 0.4 mg for 4 doses over the next 24 hours with complete recovery.(23) In a study of 8 healthy subjects, the effects of cimetidine on morphine were studied. Subjects were evaluated in three study periods: morphine 10 mg IM single dose; cimetidine 600 mg oral given one hour before morphine 10 mg IM single dose; and cimetidine 600 mg oral single dose. Morphine reduced resting ventilation and increased end-tidal CO2 with peak effects at 120 minutes and resolution at 12 hours. Morphine with cimetidine pretreatment had similar effects on resting ventilation and end-tidal CO2, however the recovery ratio from 120 to 720 minutes was significantly different than morphine alone (p<0.05).(24) In a study of 7 healthy subjects, the effects of cimetidine 300 mg oral four times daily for 4 days on morphine 10 mg IV single dose were evaluated. No significant differences were found in morphine concentrations at any time point from zero to ten hours after dose administration with and without cimetidine. Morphine elimination half-life (t1/2), systemic clearance, volume of distribution, and AUC with and without cimetidine had no statistical differences.(25) In a study of 40 patients undergoing elective coronary artery bypass graft surgery were randomized to receive either cimetidine 4 mg/kg, diphenhydramine 1 mg/kg, a combination of both cimetidine and diphenhydramine, or placebo, followed by morphine 1 mg/kg. Patients were randomized to one of four groups: 1. placebo plus morphine; 2. cimetidine plus morphine; 3. diphenhydramine plus morphine; or 4. cimetidine plus diphenhydramine plus morphine. Patients in group 1 had a 10-fold increase in plasma histamine levels within 2 minutes of morphine with a decrease in mean BP, diastolic BP, and systemic vascular resistance (SVR). Group 2 has similar effects with a peak change in SVR and plasma histamine rise within 2 minutes of morphine. The change in SVR was significant when compared to placebo but less than group 1. Group 3 patients had an increase in heart rate (HR) from diphenhydramine alone as well as peak effects within 2 minutes of morphine with decreases in BP and SVR but were less than morphine alone. Group 4 patients had a 7-fold increase in histamine with a significant increase in HR, diastolic BP, and BP. When group 4 is compared to group 1, patients had a decrease in SVR and diastolic BP that was significantly less despite comparable increases in plasma histamine.(26) In vitro testing of oxycodone and methadone, cimetidine caused a greater than 50% inhibition in all pathways: CYP2B6, CYP3A4, CYP2C18, and CYP2D6. Cimetidine was found to be a weak reversible inhibitor in vitro. Extrapolation of the data to in vivo inhibition is unlikely to produce significant inhibition unless concentrations exceed normal doses by 10-fold.(27) Two studies examined the effects of CYP2D6 and CYP3A4 on the metabolism of oxycodone as well as genetic polymorphism influences. After concurrent administration of oxycodone with ketoconazole, the Cmax of the metabolites noroxycodone and noroxymorphone were decreased by 80% from baseline.(28,29) A review discussed the metabolism of oxycodone by CYP3A4 to noroxycodone, the major metabolite with weak antinociceptive properties, and by CYP2D6 to the active minor metabolite oxymorphone.() In a study of 8 male subjects, effects of cimetidine 600 mg twice daily for seven days on pethidine 70 mg IV single dose was evaluated. Concurrent use with cimetidine was associated with a 22% decrease in clearance, 11% decrease in elimination rate, and a 13% decrease in volume of distribution of pethidine. Changes were also seen in norpethidine, the primary metabolite, with a 23% decrease in AUC and 29% decrease in Cmax.(30) Opioid analgesics linked to this monograph include: alfentanil, benzhydrocodone, dihydrocodeine, fentanyl, hydrocodone, meperidine, meptazinol, nalbuphine, oxycodone, oxymorphone, pentazocine, propoxyphene, and sufentanil. |
ACETAMIN-CAFF-DIHYDROCODEINE, APADAZ, BENZHYDROCODONE-ACETAMINOPHEN, DEMEROL, DIHYDROCODEINE BITARTRATE, DSUVIA, ENDOCET, FENTANYL, FENTANYL CITRATE, FENTANYL CITRATE-0.9% NACL, FENTANYL CITRATE-D5W, FENTANYL CITRATE-STERILE WATER, FENTANYL CITRATE-WATER, FENTANYL-BUPIVACAINE-0.9% NACL, FENTANYL-BUPIVACAINE-NACL, FENTANYL-ROPIVACAINE-0.9% NACL, FENTANYL-ROPIVACAINE-NACL, HYCODAN, HYDROCODONE BITARTRATE, HYDROCODONE BITARTRATE ER, HYDROCODONE-ACETAMINOPHEN, HYDROCODONE-CHLORPHENIRAMNE ER, HYDROCODONE-HOMATROPINE MBR, HYDROCODONE-IBUPROFEN, HYDROMET, HYSINGLA ER, MEPERIDINE HCL, MEPERIDINE HCL-0.9% NACL, NALBUPHINE HCL, NALOCET, OXYCODONE HCL, OXYCODONE HCL ER, OXYCODONE HYDROCHLORIDE, OXYCODONE-ACETAMINOPHEN, OXYCONTIN, OXYMORPHONE HCL, OXYMORPHONE HCL ER, PENTAZOCINE-NALOXONE HCL, PERCOCET, PRIMLEV, PROLATE, ROXICODONE, ROXYBOND, SUFENTANIL CITRATE, TREZIX, XTAMPZA ER |
| Mycophenolate/Aluminum & Magnesium Antacids; Lanthanum; Sevelamer SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum or magnesium antacids and non-calcium containing phosphate binders such as lanthanum and sevelamer decrease the absorption of mycophenolate.(1-3) CLINICAL EFFECTS: The simultaneous administration of mycophenolate with aluminum or magnesium antacids and non-calcium containing phosphate binders such as lanthanum and sevelamer may decrease the levels of mycophenolate and its clinical effects. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of mycophenolate mofetil states that calcium free phosphate binders, such as sevelamer, should not be administered simultaneously with mycophenolate mofetil. Administer sevelamer at least 2 hours after administration of mycophenolate mofetil to decrease the extent of the interaction.(1) The US manufacturer of mycophenolate sodium states that mycophenolate sodium should not be administered simultaneously with antacids. Administer aluminum or magnesium containing antacids at least 2 hours after mycophenolate.(2) Close monitoring of mycophenolic acid levels may be warranted in patients on mycophenolate mofetil therapy that are initiating or discontinuing concurrent therapy with these agents. Patients on concurrent therapies may also require higher doses of mycophenolate mofetil in order to achieve desired blood levels. DISCUSSION: In a study in 10 rheumatoid arthritis patients, the simultaneous administration of mycophenolate and Maalox TC (an antacid containing magnesium and aluminum hydroxide) resulted in decreases in the maximum concentration (Cmax) and area-under-curve (AUC) of mycophenolate by 33% and 17%, respectively.(1,2) In a study of 3 adult patients and 6 pediatric patients with stable renal graft function receiving mycophenolate mofetil, sevelamer (3-4 capsules of 403 mg twice daily) decreased the AUC and Cmax of mycophenolic acid by 26% and 36%, respectively.(1,3) In a study in 12 stable renal transplant patients, administration of magnesium-aluminum-containing antacids (30 ml) increased the Cmax and AUC of a single dose of mycophenolate sodium by 25% and 37%, respectively.(2) |
CELLCEPT, MYCOPHENOLATE MOFETIL, MYCOPHENOLIC ACID, MYFORTIC, MYHIBBIN |
| Zaleplon/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine inhibits the metabolism of zaleplon by aldehyde oxidase and by CYP3A4.(1) CLINICAL EFFECTS: The concurrent use of cimetidine and zaleplon may result in increased levels and clinical effects of zaleplon, including profound sedation, respiratory depression, coma, and/or death.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of zaleplon recommends that an initial dose of 5 mg of zaleplon be used in patients being concomitantly treated with cimetidine.(1) DISCUSSION: Concomitant administration of zaleplon (10 mg) and cimetidine (800 mg) resulted in an 85% increase in zaleplon maximum concentration (Cmax) and area-under-curve (AUC). Therefore, the manufacturer of zaleplon recommends that an initial dose of 5 mg of zaleplon be used in patients being concomitantly treated with cimetidine.(1) |
ZALEPLON |
| Gabapentin/Aluminum; Magnesium-Containing Compounds SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum or magnesium containing products may reduce the bioavailability of gabapentin.(1) CLINICAL EFFECTS: Simultaneous administration of aluminum or magnesium containing products and gabapentin may result in decreased absorption of gabapentin by 20% and reduce its clinical effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If the use of both medications is unavoidable, it is recommended that gabapentin be taken at least 2 hours following the administration of aluminum or magnesium containing products.(1) DISCUSSION: In 16 subjects, Maalox reduced the bioavailability of gabapentin by about 20%. The reduction was only 5% when gabapentin was administered 2 hours after the Maalox dose. It is for this reason that the manufacturer of gabapentin recommends that it be taken at least 2 hours after the administration of aluminum or magnesium containing products.(1) |
GABAPENTIN, GABAPENTIN ER, GABARONE, GRALISE, HORIZANT, NEURONTIN |
| Amprenavir; Atazanavir/Antacids; Buffered Formulations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Antacids increase gastric pH. As gastric pH increases, the solubility of atazanavir decreases.(1,2) The exact mechanism behind the interaction between amprenavir and antacids is unknown. CLINICAL EFFECTS: Simultaneous administration of amprenavir or atazanavir with antacids or buffered formulations may result in decreased levels and effectiveness of amprenavir(3) and atazanavir.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of amprenavir states that amprenavir should be administered 1 hour before or after antacids or buffered formulations such as didanosine.(3) The manufacturer of atazanavir states that atazanavir should be administered 2 hours before or 1 hour after antacids or buffered formulations.(1,2) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: Simultaneous administration of atazanavir with didanosine buffered tablets decreased atazanavir area-under-curve (AUC), maximum concentration (Cmax) and minimum concentration (Cmin) by 87%, 89% and 84%, respectively. Administration of atazanavir 1 hour after didanosine buffered tablets had no significant effect on atazanavir pharmacokinetics.(1) Other buffered formulations and antacids are expected to substantially decrease atazanavir concentrations and therapeutic effectiveness as well.(1,2) |
ATAZANAVIR SULFATE, EVOTAZ, REYATAZ |
| Atazanavir/H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: H-2 antagonists increase gastric pH. As gastric pH increases, the solubility of atazanavir decreases.(1,2) CLINICAL EFFECTS: Concurrent use of atazanavir and a H-2 antagonist may result in decreased levels and effectiveness of atazanavir.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The Australian and US manufacturers of atazanavir(1,2) and cobicistat(3,4) state that patients who require H-2 antagonist therapy should receive atazanavir 300 mg daily with ritonavir 100 mg daily or cobicistat 150 mg daily, taken with and/or at least 10 hours after the H-2 antagonist dose. Patients who are also on tenofovir in addition to atazanavir and a H-2 antagonist should receive atazanavir 400 mg daily with ritonavir 100 mg daily or cobicistat 150 mg daily.(2,3,5) The dose of the H-2 antagonist should not exceed the equivalent of famotidine 40 mg twice daily in treatment-naive patients, and 20 mg twice daily in treatment-experienced patients.(2-5) Treatment-experienced pregnant patients in the second or third trimester on concurrent tenofovir disoproxil should have their atazanavir dose increased to 400 mg with ritonavir 100 mg daily. The use of atazanavir with both a H2-antagonist and tenofovir in treatment-experienced pregnant women is not recommended.(2) The Australian manufacturer of atazanavir states that atazanavir without ritonavir is not recommended when co-administered with H-2 antagonists.(1) The US manufacturer of atazanavir states that treatment-naive patients who are unable to tolerate ritonavir or cobicistat should receive atazanavir 400 mg daily with food at least 2 hours before and at least 10 hours after the H-2 antagonist. The H-2 antagonist dose should not exceed the equivalent of a 20 mg single dose of famotidine and the total daily dose should not exceed a 40 mg equivalent dose of famotidine. Treatment-experienced patients should not use unboosted atazanavir with a H-2 antagonist.(2) The US manufacturer of atazanavir states that atazanavir should not be administered without ritonavir in pediatric patients at least 13 years of age who weigh at least 40 kg who are receiving a H2 antagonist. Data are not sufficient to recommend a dose of atazanavir in patients weighing less than 40 kg.(2) DISCUSSION: In a study in 15 subjects, simultaneous administration of atazanavir (400 mg daily) with famotidine (40 mg twice daily) decreased the atazanavir maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) by 47%, 41%, and 42%, respectively.(2) In a study in 14 subjects, atazanavir (400 mg daily) was administered 2 hours before and 10 hours after famotidine (40 mg twice daily). Atazanavir Cmax increased 8%. Atazanavir AUC and Cmin decreased by 5% and 21%, respectively.(2) In a study in 14 subjects, atazanavir (300 mg daily) and ritonavir (100 mg daily) were administered simultaneously with famotidine (40 mg twice daily). Atazanavir Cmax, AUC, and Cmin decreased by 14%, 18%, and 28%, respectively, compared to the same regimen alone. However, atazanavir Cmax was similar to levels seen with atazanavir 400 mg alone. Atazanavir AUC and Cmin were 1.79-fold and 4.46-fold higher than levels seen with atazanavir 400 mg alone.(2) In a study in 18 subjects, simultaneous administration of famotidine (20 mg twice daily) and atazanavir/ritonavir (300/100 mg daily) decreased the Cmax, AUC, and Cmin of atazanavir by 9%, 10%, and 19%, respectively.(2) In a study in 20 subjects, administration of atazanavir/ritonavir/tenofovir (300/100/300 mg daily) 12 hours after famotidine (40 mg daily) decreased the Cmax, AUC, and Cmin of atazanavir by 11%, 12%, and 23%, respectively.(2) In a study in 18 subjects, administration of atazanavir/ritonavir/tenofovir (300/100/300 mg daily) 12 hours after the evening dose and two hours before the morning dose of famotidine (40 mg twice daily) decreased the Cmax, AUC, and Cmin of atazanavir by 26%, 21%, and 28%, respectively.(2) In a study in 15 subjects, administration of atazanavir/ritonavir (400/100 mg) with famotidine (40 mg twice daily) decreased atazanavir Cmin by 14%. There were no significant effects on atazanavir Cmax or AUC.(2) |
ATAZANAVIR SULFATE, EVOTAZ, REYATAZ |
| Selected Cephalosporins/Aluminum; Magnesium Compounds SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum and magnesium containing antacids may form chelation complexes with some cephalosporins, preventing their absorption.(1,2) CLINICAL EFFECTS: Simultaneous administration of an aluminum and/or magnesium containing antacid with some cephalosporins may result in decreased levels and effectiveness of the cephalosporin.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of cefdinir recommends that cefdinir be taken at least 2 hours before or after an aluminum and/or magnesium containing antacid.(1) It would be prudent to separate the administration of cefaclor by at least this amount of time as well.(2) DISCUSSION: Simultaneous administration of cefdinir (300 mg) with Maalox TC (30 ml) decreased cefdinir area-under-curve (AUC) and maximum concentration (Cmax) by 40%.(1) In a study in 15 healthy subjects, simultaneous administration of cefaclor advanced formulation (500 mg) with Maalox TC decreased the extent of cefaclor absorption.(2) |
CEFACLOR, CEFACLOR ER, CEFDINIR |
| Metformin/MATE Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of the Multidrug and Toxin Extrusion (MATE) protein transporters in the kidneys may interfere with the renal tubular secretion of metformin.(1) CLINICAL EFFECTS: Concurrent use may result in increased plasma levels of metformin and toxicity such as lactic acidosis. Untreated lactic acidosis may be fatal. Symptoms of lactic acidosis include malaise, myalgias, respiratory distress, low pH, increased anion gap and elevated blood lactate. PREDISPOSING FACTORS: Risk factors for metformin associated lactic acidosis include renal impairment,sepsis, dehydration, excessive alcohol intake, acute or chronic metabolic acidosis, hepatic insufficiency, acute heart failure, metformin plasma levels > 5 micrograms/mL, and conditions which may lead to tissue hypoxia. Geriatric patients may also be at higher risk due to slower metformin clearance and increased half-life in this population. The risk for metabolic acidosis is higher with increased doses of either agent. PATIENT MANAGEMENT: Use an alternative agent if possible. If both drugs are given, monitor patient's renal function and for signs and symptoms of metformin toxicity (lactic acidosis) such as malaise, myalgias, respiratory distress, increasing somnolence, and respiratory distress. Laboratory results which may signal lactic acidosis include: low pH, an increased anion gap, and increased lactate to pyruvate ratio. Dosage of either agent may need to be adjusted.(1) DISCUSSION: In a study of normal healthy volunteers, concurrent metformin and oral cimetidine increased metformin maximum concentration (Cmax) in plasma and whole blood by 60% and increased metformin area-under-curve (AUC) levels in plasma and whole blood by 40%.(1) In a study in 7 subjects, concurrent metformin (250 mg daily) with cimetidine (400 mg twice daily) increased metformin AUC by 50%. Metformin renal clearance over 24 hours was reduced by 27%.(2) MATE inhibitors include: cimetidine, pyrimethamine, and risdiplam.(3) |
ACTOPLUS MET, ALOGLIPTIN-METFORMIN, DAPAGLIFLOZIN-METFORMIN ER, GLIPIZIDE-METFORMIN, GLYBURIDE-METFORMIN HCL, INVOKAMET, INVOKAMET XR, JANUMET, JANUMET XR, JENTADUETO, JENTADUETO XR, KAZANO, METFORMIN ER GASTRIC, METFORMIN ER OSMOTIC, METFORMIN HCL, METFORMIN HCL ER, PIOGLITAZONE-METFORMIN, RIOMET, SAXAGLIPTIN-METFORMIN ER, SEGLUROMET, SITAGLIPTIN-METFORMIN, SITAGLIPTIN-METFORMIN ER, SYNJARDY, SYNJARDY XR, TRIJARDY XR, XIGDUO XR, ZITUVIMET, ZITUVIMET XR |
| Loperamide/CYP3A4; CYP2C8; P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP3A4, CYP2C8, and/or P-gp may increase loperamide systemic absorption and facilitate entry into central nervous system (CNS).(1) CLINICAL EFFECTS: Concurrent use of inhibitors of CYP3A4, CYP2C8, and/or P-gp may increase levels of loperamide, resulting in respiratory depression.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Use loperamide with caution in patients receiving inhibitors of CYP3A4, CYP2C8, and/or P-gp. Consider lower doses of loperamide in these patients and monitor for adverse effects. The manufacturer of lonafarnib recommends starting loperamide at a dose of 1 mg and slowly increasing the dose as needed.(2) DISCUSSION: In a randomized, cross-over study in 12 healthy subjects, itraconazole (100 mg twice daily for 5 days - first dose 200 mg), gemfibrozil (600 mg twice daily), and the combination of itraconazole and gemfibrozil (same dosages) increased the area-under-curve (AUC) of single doses of loperamide (4 mg) by 2.9-fold, 1.6-fold, and 4.2-fold, respectively.(3) In a study of healthy subjects, lonafarnib (100 mg twice daily for 5 days) increased the AUC and maximum concentration (Cmax) of single dose loperamide (2 mg) by 299% and 214%, respectively.(3) In a study in 18 healthy males, quinidine increased the AUC of a single dose of loperamide by 2.2-fold and markedly decreased pupil size.(4) In a study in 8 healthy subjects, subjects experienced respiratory depression when a single dose of loperamide (16 mg) was administered with a single dose of quinidine (600 mg) but not when loperamide was administered alone.(6) Loperamide plasma levels increased 2-fold to 3-fold.(5) |
LOPERAMIDE |
| Selected Kinase Inhibitors/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The solubility of bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib(8) is pH dependent. Antacid-induced changes in gastric pH may decrease the absorption of these agents.(1-8) CLINICAL EFFECTS: Simultaneous administration of antacids may result in decreased levels and effectiveness of bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib.(8) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Antacid use should be considered in place of H2 blockers or proton pump inhibitors in patients receiving bosutinib,(1) dasatinib,(2) erlotinib,(3) gefitinib,(4) neratinib,(5) nilotinib(6), pazopanib,(7) and pexidartinib;(8) however, separation of administration times is required. If antacids are used, separate the administration times by several hours(1-8) but at least 2 hours for bosutinib,(1) dasatinib,(2) nilotinib,(6) and pexidartinib(8), 6 hours for gefitinib,(4) and 3 hours for neratinib.(5) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: In a study in 24 healthy subjects, lansoprazole (60 mg) decreased bosutinib (400 mg single dose) area-under-curve (AUC) and maximum concentration (Cmax) by 26% and 46%, respectively.(1) In a study in 24 healthy subjects, simultaneous administration of dasatinib (50 mg) with aluminum hydroxide/magnesium hydroxide (30 ml) decreased dasatinib AUC and Cmax by 55% and 58%, respectively. In the same subjects, administration of the antacid 2 hours before dasatinib decreased dasatinib Cmax by 26%, but had no effect on dasatinib AUC.(2) In a study in 24 healthy subjects, administration of a single dose of dasatinib (50 mg) 10 hours after famotidine decreased dasatinib AUC and Cmax by 61% and 63%, respectively.(2) In a study, concurrent omeprazole decreased the AUC and Cmax of erlotinib by 46% and 61%, respectively.3) In a study, concurrent esomeprazole decreased the AUC of nilotinib by 34%.(6) In a study in 15 healthy subjects, lansoprazole (30 mg at steady state) decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(5) There were no significant changes in nilotinib pharmacokinetics when famotidine was administered 10 hours before or 2 hours after nilotinib.(6) There were no significant changes in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered 2 hours before or after nilotinib.(6) Coadministration of esomeprazole decreased pexidartinib Cmax and AUC by 55% and 50%.(8) |
BOSULIF, DANZITEN, DASATINIB, ERLOTINIB HCL, GEFITINIB, IRESSA, NERLYNX, NILOTINIB HCL, NILOTINIB TARTRATE, PAZOPANIB HCL, SPRYCEL, TASIGNA, TURALIO, VOTRIENT |
| Amphetamines/H2 Antagonists; Proton Pump Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: H2 antagonists and proton pump inhibitors (PPIs) may alter the timing of absorption of amphetamines. CLINICAL EFFECTS: Concurrent use of amphetamines and H2 antagonists or PPIs may result in an increased absorption rate and a change in timing of peak amphetamine levels. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer states that patients receiving concurrent amphetamines and H2 antagonists or PPIs should be monitored for changes in the timing and clinical effects of amphetamines.(1) Monitor patients receiving concurrent therapy for changes in amphetamine effectiveness and side effects. The Canadian manufacturer states that concurrent use of proton pump inhibitors and amphetamines should be avoided.(3) DISCUSSION: During concurrent use of a proton pump inhibitor, the median time to maximum concentration (Tmax) of Adderall XR decreased from 5 hours to 2.75 hours.(3) In a 4-way crossover study in healthy subjects, omeprazole had no effect on the total exposure a single dose of mixed amphetamine salts (20 mg); however median Tmax decreased from 5 hours to 2.75 hours. Approximately 50% of subjects had a decrease in Tmax of equal to or greater than 1 hour.(4) |
ADDERALL, ADDERALL XR, ADZENYS XR-ODT, AMPHETAMINE SULFATE, DESOXYN, DEXEDRINE, DEXTROAMPHETAMINE SULFATE, DEXTROAMPHETAMINE SULFATE ER, DEXTROAMPHETAMINE-AMPHET ER, DEXTROAMPHETAMINE-AMPHETAMINE, DYANAVEL XR, EVEKEO, METHAMPHETAMINE HCL, MYDAYIS, PROCENTRA, ZENZEDI |
| Tamoxifen/Selected Weak CYP2D6 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP2D6 may inhibit the conversion of tamoxifen to endoxifen (an active metabolite of tamoxifen).(1-2) The role of endoxifen in tamoxifen's efficacy has been debated and may involve a minimum concentration level.(3-5) CLINICAL EFFECTS: Concurrent use of inhibitors of CYP2D6 may decrease the effectiveness of tamoxifen in preventing breast cancer recurrence. PREDISPOSING FACTORS: Concurrent use of weak CYP2D6 inhibitors in patients who are CYP2D6 intermediate metabolizers should be avoided. Patients who are CYP2D6 poor metabolizers lack CYP2D6 function and are not affected by CYP2D6 inhibition. PATIENT MANAGEMENT: Although data on this interaction are conflicting, it may be prudent to use alternatives to CYP2D6 inhibitors when possible in patients taking tamoxifen. The US manufacturer of tamoxifen states that the impact on the efficacy of tamoxifen by strong CYP2D6 inhibitors is uncertain and makes no recommendation regarding coadministration with inhibitors of CYP2D6.(12) The manufacturer of paroxetine (a strong CYP2D6 inhibitor) states that alternative agents with little or no CYP2D6 inhibition should be considered.(13) The National Comprehensive Cancer Network's breast cancer guidelines advises caution when coadministering strong CYP2D6 inhibitors with tamoxifen.(14) If concurrent therapy is warranted, the risks versus benefits should be discussed with the patient. DISCUSSION: Some studies have suggested that administration of fluoxetine, paroxetine, and quinidine with tamoxifen or a CYP2D6 poor metabolizer phenotype may result in a decrease in the formation of endoxifen (an active metabolite of tamoxifen) and a shorter time to breast cancer recurrence.(1-2,9) A retrospective study of 630 breast cancer patients found an increasing risk of breast cancer mortality with increasing durations of coadministration of tamoxifen and paroxetine. In the adjusted analysis, absolute increases of 25%, 50%, and 75% in the proportion of time of overlapping use of tamoxifen with paroxetine was associated with 24%, 54%, and 91% increase in the risk of death from breast cancer, respectively.(16) The CYP2D6 genotype of the patient may have a role in the effects of this interaction. Patients with wild-type CYP2D6 genotype may be affected to a greater extent by this interaction. Patients with a variant CYP2D6 genotype may have lower baseline levels of endoxifen and may be affected to a lesser extent by this interaction.(6-10) In a retrospective review, 1,325 patients treated with tamoxifen for breast cancer were classified as being poor 2D6 metabolizers (lacking functional CYP2D6 enzymes), intermediate metabolizers (heterozygous alleles), or extensive metabolizers (possessing 2 functional alleles). After a mean follow-up period of 6.3 years, the recurrence rates were 14.9%, 20.9%, and 29.0%, in extensive metabolizers, intermediate metabolizers, and poor metabolizers, respectively.(11) In October of 2006, the Advisory Committee Pharmaceutical Science, Clinical Pharmacology Subcommittee of the US Food and Drug Administration recommended that the US tamoxifen labeling be updated to include information about the increased risk of breast cancer recurrence in poor CYP2D6 metabolizers (either by genotype or drug interaction).(17-18) The labeling changes were never made due to ongoing uncertainty about the effects of CYP2D6 genotypes on tamoxifen efficacy. In contrast to the above information, two studies have shown no relationship between CYP2D6 genotype and breast cancer outcome.(19-21) As well, a number of studies found no association between use of CYP2D6 inhibitors and/or antidepressants in patients on tamoxifen and breast cancer recurrence,(22-26) though the studies were limited by problematic selection of CYP2D6 inhibitors and short follow-up. Weak inhibitors of CYP2D6 include: alogliptin, artesunate, celecoxib, chloroquine, cimetidine, clobazam, clomipramine, cobicistat, delavirdine, diltiazem, dimenhydrinate, diphenhydramine, dronabinol, dupilumab, echinacea, enasidenib, fedratinib, felodipine, fluvoxamine, gefitinib, hydralazine, imatinib, labetalol, lorcaserin, nicardipine, osilodrostat, ranitidine, ritonavir, sertraline, verapamil and viloxazine.(27) |
SOLTAMOX, TAMOXIFEN CITRATE |
| Oral Bisphosphonates/Oral Multivalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Multivalent cations may bind to and inhibit the absorption of oral bisphosphonates.(1-6) CLINICAL EFFECTS: Simultaneous administration of products containing multivalent cations may result in decreased levels of and clinical effects from oral bisphosphonates.(1-6) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Instruct patients to separate the administration times of products containing multivalent cations and oral bisphosphonates. Manufacturer recommendations regarding the separation of administration times of oral bisphosphonates and multivalent cations vary. Do NOT give multivalent cation-containing products: - until at least 30 minutes after taking alendronate(1) - within 2 hours of etidronate(2) - until at least 1 hour after taking ibandronate(3) - until at least 30 minutes after taking risedronate(4) - within 2 hours of tiludronate(5) DISCUSSION: Multivalent cations may bind to and inhibit the absorption of oral bisphosphonates, resulting in decreased levels of and clinical effects from these agents.(1-6) Administration of aluminum- or magnesium-containing antacids 1 hour before tiludronate decreased the bioavailability of tiludronate by 60%.(5) |
ACTONEL, ALENDRONATE SODIUM, ATELVIA, BINOSTO, FOSAMAX, FOSAMAX PLUS D, IBANDRONATE SODIUM, RISEDRONATE SODIUM, RISEDRONATE SODIUM DR |
| Chloroquine; Hydroxychloroquine/Di-; Trivalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Di- and trivalent cations such as aluminum, calcium, lanthanum, and magnesium may adsorb chloroquine and hydroxychloroquine; preventing their absorption.(1-5) The adsorption may also limit the effectiveness of the di- or trivalent cation.(1) CLINICAL EFFECTS: Simultaneous administration of di- or trivalent cations may result in decreased levels and effectiveness of chloroquine and hydroxychloroquine(2-5) and decreased effectiveness of the di- or trivalent cation.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Instruct patients to separate the administration times of these medicines by 2 to 4 hours.(2,3) DISCUSSION: Adsorption of chloroquine by magnesium trisilicate was found to decrease hydrochloric acid uptake and decrease the amount of magnesium released in an acidic environment.(1) In a study, calcium carbonate, kaolin, and magnesium trisilicate were found to decrease the absorption of chloroquine by 52.8%, 46.5%, and 31.3%, respectively.(3) Magnesium trisilicate and magnesium oxide have been shown to decrease the release of chloroquine from tablets and to adsorb chloroquine after its release.(4) In a study in 6 subjects, magnesium trisilicate and kaolin decreased the area-under-curve (AUC) of chloroquine by 18.2% and 28.6%, respectively.(5) |
CHLOROQUINE PHOSPHATE, HYDROXYCHLOROQUINE SULFATE, PLAQUENIL, SOVUNA |
| Oral Iron Supplements/Antacids and Selected Minerals SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Some antacids may bind to iron, preventing its absorption. Alterations in gastric pH by antacids may also play a role. Iron may bind to other minerals such as calcium, manganese, tin, and zinc in the GI tract. CLINICAL EFFECTS: Simultaneous administration of an antacid or minerals may decrease the absorption of orally administered iron. PREDISPOSING FACTORS: The interaction with some combinations may be affected by the presence or absence of food. PATIENT MANAGEMENT: Iron supplements should not be taken within 1 hour before or 2 hours after antacids, calcium, manganese, or zinc.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: Magnesium hydroxide has been shown to inhibit the absorption of elemental iron,(2) although other studies have shown conflicting results.(3,4) Sodium bicarbonate has been shown to decrease the absorption of iron by 50%.(3) In a study in 61 healthy subjects, calcium citrate, calcium carbonate, and calcium phosphate inhibited iron absorption when taken with food. However, in the fasted state, calcium carbonate had no effect on iron absorption. In the fasted state, calcium citrate and calcium phosphate decreased iron absorption by 49% and 62%, respectively,(6) In a study in 23 healthy subjects, calcium acetate and calcium carbonate decreased the area-under-curve (AUC) of elemental iron (65 mg) by 27% and 19%, respectively.(7) In a study, manganese decreased iron absorption. A ratio of 5:1 of zinc:iron decreased iron absorption by 56%.(8) In a study, inorganic iron decreased zinc absorption.(9) In another study, ferrous sulfate decreased the absorption of zinc sulfate in a concentration dependent manner; however, heme chloride had no effect on zinc sulfate.(10) In a study in premature infants, administration of liquid zinc and iron supplements between feedings decreased iron uptake; however, no effect was seen when the supplements were mixed with feedings.(11) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
ACCRUFER, AUROVELA 24 FE, AUROVELA FE, AURYXIA, AVERI, BALCOLTRA, BLISOVI 24 FE, BLISOVI FE, CHARLOTTE 24 FE, FEIRZA, FERRIC CITRATE, FINZALA, GALBRIELA, GEMMILY, HAILEY 24 FE, HAILEY FE, JOYEAUX, JUNEL FE, JUNEL FE 24, KAITLIB FE, LARIN 24 FE, LARIN FE, LEVONORG-ETH ESTRAD-FE BISGLYC, LO LOESTRIN FE, LOESTRIN FE, MERZEE, MIBELAS 24 FE, MICROGESTIN FE, MINZOYA, NORETHIN-ETH ESTRA-FERROUS FUM, NORETHINDRONE-E.ESTRADIOL-IRON, TARINA 24 FE, TARINA FE, TARINA FE 1-20 EQ, TAYTULLA, TILIA FE, TRI-LEGEST FE, VELPHORO, WYMZYA FE, XARAH FE, XELRIA FE |
| Phenytoin/Aluminum-Magnesium Hydroxide; Oral Calcium SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum hydroxide; magnesium hydroxide, and oral calcium may bind to phenytoin, preventing its absorption.(1-4) CLINICAL EFFECTS: Simultaneous ingestion of aluminum-magnesium hydroxide and/or calcium-containing products may result in decreased levels and effectiveness of phenytoin.(1-4) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of phenytoin recommends that administration times of phenytoin and antacids being staggered.(1) DISCUSSION: In a study in 8 healthy subjects, simultaneous administration of phenytoin (600 mg) with calcium carbonate significantly decreased the area-under-curve (AUC) of phenytoin.(2) In a study in 8 healthy subjects, simultaneous administration of aluminum-magnesium hydroxide or calcium carbonate significantly decreased the AUC of phenytoin.(3) In a study in 6 patients with epilepsy, concurrent administration of an aluminum-magnesium hydroxide antacid resulted in a small but statistically significant decrease in phenytoin AUC.(4) |
DILANTIN, DILANTIN-125, PHENYTEK, PHENYTOIN, PHENYTOIN SODIUM, PHENYTOIN SODIUM EXTENDED |
| Rosuvastatin/Aluminum Hydroxide; Magnesium Hydroxide SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The mechanism of action is not known, but it theorized to be caused by aluminum/magnesium binding to rosuvastatin in the gastrointestinal tract and/or an increase in gastric pH.(1) CLINICAL EFFECTS: Simultaneous administration of aluminum hydroxide/magnesium hydroxide with rosuvastatin may decrease the clinical effects of rosuvastatin. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of rosuvastatin states that patients receiving concurrent aluminum hydroxide/magnesium hydroxide and rosuvastatin should take the antacid at least 2 hours after taking the rosuvastatin.(2) DISCUSSION: In a randomized, open-label, cross-over trial in 14 healthy males, concurrent use of (20 ml) aluminum hydroxide(200 mg/5 ml)/magnesium hydroxide(195 mg/5 ml)and rosuvastatin (40 mg) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of rosuvastatin by 54% and 50%, respectively. However, the interaction was determined to be clinically insignificant when administration was separated by 2 hours.(1,2) |
CRESTOR, EZALLOR SPRINKLE, ROSUVASTATIN CALCIUM, ROSUVASTATIN-EZETIMIBE, ROSZET |
| Eltrombopag/Polyvalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Eltrombopag chelates polyvalent cations such as aluminum, calcium, iron, magnesium, selenium, and zinc.(1) CLINICAL EFFECTS: Simultaneous administration of eltrombopag and polyvalent cations may decrease the absorption and clinical effects of eltrombopag. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of eltrombopag states that it should be administered at least 2 hours before or 4 hours after any medications or products containing polyvalent cations such as antacids or mineral supplements.(1) DISCUSSION: In a crossover study in 25 healthy subjects, administration of eltrombopag with an antacid (1524 mg aluminum hydroxide/1425 mg magnesium carbonate/sodium alginate) decreased eltrombopag levels by 70%.(1,2) |
ALVAIZ, ELTROMBOPAG OLAMINE, PROMACTA |
| Ethambutol/Aluminum hydroxide SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum hydroxide may bind to ethambutol in the gastrointestinal tract, preventing its absorption. CLINICAL EFFECTS: Simultaneous administration of an aluminum hydroxide-containing antacid may decrease levels and effectiveness of ethambutol.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of ethambutol recommends that the administration times of ethambutol and aluminum hydroxide-containing antacids be separated by 4 hours.(1) DISCUSSION: In a study in 13 tuberculosis patients, simultaneous administration of ethambutol with aluminum hydroxide decreased the area-under-curve (AUC) and urinary excretion of ethambutol by 20% and 13%, respectively.(1,2) In a study in 14 healthy subjects, simultaneous administration of ethambutol with an aluminum-magnesium antacid, ethambutol AUC and maximum concentration (Cmax) decreased by 10% and 29%, respectively.(3) |
ETHAMBUTOL HCL |
| Everolimus/Moderate CYP3A4; P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate inhibitors of CYP3A4 and/or p-glycoprotein (P-gp) may inhibit the metabolism of everolimus.(1) CLINICAL EFFECTS: Concurrent use of moderate inhibitors of CYP3A4 and/or P-gp may result in elevated levels of and toxicity from everolimus.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If concurrent therapy with everolimus and moderate inhibitors of CYP3A4 and/or P-gp is warranted, reduce the dosage of everolimus.(1) In patients with advanced hormone receptor-positive, HER2-negative breast cancer (HR+BC); advanced pancreatic neuroendocrine tumors (PNET); or advanced renal cell carcinoma; or renal angiomyolipoma with TSC, decrease the dose of everolimus to 2.5 mg daily. An increase to 5 mg daily may be considered based on patient tolerance. If the inhibitor is discontinued, allow an elimination period of 2-3 days before increasing the dose to that used prior to the inhibitor.(1) In patients with subependymal giant cell astrocytoma with TSC, reduce the dosage of everolimus by 50% to maintain trough concentrations of 5 ng/ml to 15 ng/ml. If the patient is already receiving 2.5 mg daily, consider a dose of 2.5 mg every other day. Assess everolimus levels 2 weeks after the addition of the inhibitor. Resume the everolimus dose used prior to initiation of the inhibitor after the inhibitor has been discontinued for 3 days, and assess everolimus trough levels 2 weeks later.(1) Guidelines from the American Society of Transplantation state that protease inhibitors are contraindicated, and recommend avoiding the use of erythromycin with everolimus. If the combination must be used, lower the dose of everolimus by up to 50% upon initiation of the antibiotic and monitor levels daily.(3) DISCUSSION: In a study in healthy subjects, concurrent use of erythromycin, a moderate CYP3A4 inhibitor and a P-gp inhibitor, increased everolimus AUC and Cmax by 2.0-fold and 4.4-fold, respectively.(1) In a study in healthy subjects, concurrent use of ketoconazole, a strong CYP3A4 inhibitor and a P-gp inhibitor, increased everolimus area-under-curve (AUC) and maximum concentration (Cmax) by 3.9-fold and 15.0-fold, respectively.(1) In a study in healthy subjects, concurrent use of verapamil, a moderate CYP3A4 inhibitor and a P-gp inhibitor, increased everolimus AUC and Cmax by 2.3-fold and 3.5-fold, respectively.(1) In a study in 16 healthy subjects, concurrent use of verapamil increased everolimus Cmax and AUC by 130% and 250%, respectively.(4) Moderate CYP3A4 and/or P-gp inhibitors include: abrocitinib, amiodarone, amprenavir, aprepitant, asciminib, asunaprevir, atazanavir, avacopan, azithromycin, belumosudil, cimetidine, clofazimine, conivaptan, crizotinib, danicopan, daridorexant, delavirdine, diltiazem, diosmin, dronedarone, duvelisib, erythromycin, fedratinib, flibanserin, fluconazole, fluvoxamine, fosamprenavir, fosnetupitant, fostamatinib, imatinib, isavuconazonium, ivacaftor, ledipasvir, lenacapavir, letermovir, mavorixafor, netupitant, nilotinib, nirogacestat, pirtobrutinib, propafenone, schisandra, stiripentol, tepotinib, tezacaftor, tofisopam, treosulfan, vemurafenib, verapamil, vimseltinib, and voclosporin.(5-7) |
AFINITOR, AFINITOR DISPERZ, EVEROLIMUS, TORPENZ, ZORTRESS |
| Selected Oral Quinolones/Selected Oral Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum, calcium, iron, lanthanum, magnesium, and zinc may form chelation compounds with the quinolones.(1-40) CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or zinc close to the administration time of an oral quinolone may result in decreased absorption and clinical effectiveness of the quinolone. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If possible, avoid concurrent therapy with quinolones and cation-containing products. If it is necessary to administer these agents concurrently, follow the manufacturers' recommendations regarding timing of administration of the quinolone and cation-containing products. Manufacturer recommendations regarding the separation of administration times of quinolones and products containing aluminum, calcium, iron, lanthanum, magnesium, and/or zinc vary: ---Do not give ciprofloxacin for at least 2 hours before or 6 hours after oral cations.(1) ---Do not give delafloxacin for at least 2 hours before or 6 hours after oral cations.(2) ---Do not give enoxacin for at least 2 hours before or 8 hours after oral cations.(3) ---Do not give levofloxacin for at least 2 hours before or 2 hours after oral cations.(4) ---Do not give nalidixic acid for at least 2 hours before or 2 hours after oral cations.(5) ---Do not give norfloxacin for at least 2 hours before or 2 hours after oral cations.(6) ---Do not give ofloxacin for at least 2 hours before or 2 hours after oral cations.(7) ---Do not give sparfloxacin for at least 4 hours before oral cations.(8) ---Do not give sitafloxacin for at least 2 hours before or 2 hours after oral cations.(9) The US manufacturer of lanthanum recommends that quinolones be taken at least 1 hour before or 4 hours after lanthanum;(10) however, it would be prudent to follow the specific quinolone manufacturers' recommendations regarding concurrent administration of cations. For quinolones not listed above, separate their administration from oral cations by as much time as feasible. DISCUSSION: Aluminum, calcium, iron, magnesium, and zinc products have been shown to form chelation compounds with quinolone antibiotics, resulting in decreased absorption of the quinolone.(1-40) Treatment failures have been reported.(11-12) In a study in 12 healthy subjects, simultaneous administration of didanosine chewable tablets, which contain aluminum and magnesium, decreased ciprofloxacin area-under-curve (AUC) and maximum concentration (Cmax) by 92% and 98%, respectively.(14) The administration of ciprofloxacin 2 hours prior to Videx chewable/dispersible tablets decreased ciprofloxacin concentrations by 26%.(15,16) In a study in healthy subjects, pretreatment with an antacid containing aluminum-magnesium hydroxide at 5-10 minutes, 2 hours, and 4 hours before a single dose of ciprofloxacin decreased ciprofloxacin AUC by 84.9%, 76.8%, and 30%, respectively. There was no effect when the antacid was administered 6 hours before or 2 hours after.(17) In a study in 12 healthy subjects, aluminum hydroxide decreased ciprofloxacin AUC by 85%.(18) In a study in patients on continuous ambulatory peritoneal dialysis, peak levels of ciprofloxacin were decreased by 67% to 92% in patients receiving aluminum-containing antacids.(19) In a study in 15 healthy subjects, simultaneous administration of calcium acetate decreased the bioavailability of ciprofloxacin by 51%.(20) In a study in 6 healthy males, simultaneous administration of calcium carbonate decreased ciprofloxacin Cmax and AUC by 40% and 43%, respectively.(21) In a study in 12 healthy subjects, calcium carbonate decreased ciprofloxacin AUC by 40%.(18) In a study in 13 healthy males, calcium carbonate had no effect on ciprofloxacin bioavailability when administered 2 hours prior to the antibiotic.(22,23) In a study in healthy males, simultaneous administration of calcium polycarbophil decreased ciprofloxacin AUC by 50%.(24) In a study in 8 healthy males, simultaneous administration of ferrous fumarate (200 mg) decreased ciprofloxacin AUC by 70%.(25) In a study in healthy subjects, ferrous gluconate decreased ciprofloxacin bioavailability by 50%; however, no significant effects were seen with iron-ovotransferrin.(26) In a study in 8 healthy subjects, ferrous sulfate decreased the Cmax and AUC of simultaneously administered ciprofloxacin by 54% and 57%, respectively.(27) In a study in 8 healthy subjects, administration of ferrous sulfate decreased the Cmax and AUC of ciprofloxacin by 33% and 46%, respectively. Administration of ferrous gluconate decreased the Cmax and AUC of ciprofloxacin by 57% and 67%, respectively. Administration of a multivitamin product containing calcium, copper, iron, magnesium, manganese, and zinc decreased the Cmax and AUC of ciprofloxacin by 53% and 56%, respectively.(28) In a study in 12 healthy males, ferrous sulfate decreased ciprofloxacin AUC by 63%.(29) In a study in 12 healthy subjects, lanthanum carbonate decreased the area-under-curve (AUC) and maximum concentration (Cmax) of concurrently administered ciprofloxacin by 54% and 56%, respectively.(30) In a study in 12 healthy males, a multivitamin containing zinc decreased ciprofloxacin AUC by 22%.(29) In a study in 12 healthy subjects, an antacid containing aluminum-magnesium hydroxide had no effect on the pharmacokinetics of intravenous enoxacin.(31) In a study in 10 healthy subjects, administration of an aluminum-magnesium hydroxide antacid 0.5 hours or 2 hours before oral enoxacin (400 mg single dose) decreased the AUC of enoxacin by 73% and 43%, respectively. There were no significant effects on enoxacin AUC when the antacid was administered 8 hours before or 2 hours after enoxacin.(32) In a study in 9 healthy subjects, colloidal aluminum phosphate had no effect on the amount of enoxacin absorbed; however, ferrous sulfate (1050 mg) decreased the amount of enoxacin absorption by 10%.(33) In a study in 5 healthy subjects and 5 patients with cystic fibrosis, separation of levofloxacin (750 mg) and calcium carbonate (500 mg 3 times daily with meals) by 2 hours resulted in no interaction in healthy subjects; however, levofloxacin levels were not bioequivalent in patients with cystic fibrosis.(34) Concurrent magnesium-aluminum hydroxide or calcium have been shown to decrease the bioavailability of norfloxacin by 91.0% and 63.5%, respectively.(35) Concurrent zinc has been shown to decrease the bioavailability of norfloxacin.(36) In a study in 8 healthy subjects, ferrous sulfate decreased the Cmax and AUC of simultaneously administered norfloxacin by 75% and 73%, respectively.(27) Simultaneous aluminum phosphate was found to decrease the rate, but not the extent, of absorption of ofloxacin.(37) In a study in 8 healthy subjects, ferrous sulfate decreased the Cmax and AUC of simultaneously administered norfloxacin by 36% and 25%, respectively.(27) In an in vitro study, ferrous sulfate, aluminum hydroxide, and calcium carbonate decreased ofloxacin availability by 32.6%, 30.7%, and 26.2%, respectively. However, in vivo tests showed a significant effect with only aluminum hydroxide.(38) In a study in 9 healthy subjects, simultaneous administration colloidal aluminum phosphate had no effect on ofloxacin (200 mg) absorption; however, ferrous sulfate (1050 mg) decreased the ofloxacin fraction of dose absorbed by 10.85%.(33) In a study in 16 subjects, administration of either aluminum-magnesium hydroxide or calcium carbonate at least 2 hours before or after ofloxacin administration had no significant effects on ofloxacin levels.(39) The administration of an antacid containing aluminum hydroxide and magnesium hydroxide 2 hours before, 2 hours after, and 4 hours after sparfloxacin decreased sparfloxacin levels by 23%, 17%, and 5%, respectively.(40) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
BAXDELA, CIPRO, CIPROFLOXACIN, CIPROFLOXACIN HCL, LEVOFLOXACIN, LEVOFLOXACIN HEMIHYDRATE, NALIDIXIC ACID, OFLOXACIN |
| Rilpivirine/Antacids; H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Rilpivirine requires an acidic medium for absorption. Antacid or H2 antagonist induced decrease in gastric pH may result in a decrease in rilpivirine absorption.(1) CLINICAL EFFECTS: Simultaneous administration of an antacid or a H2 antagonist may result in decreased levels and effectiveness of rilpivirine, as well as the development of resistance.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: In patients maintained on rilpivirine, administer antacids at least 2 hours before or 4 hours after rilpivirine.(1) In patients maintained on rilpivirine, administer H2 antagonists at least 12 hours before or 4 hours after rilpivirine.(1) Concurrent use of proton pump inhibitors with rilpivirine is contraindicated.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: In a study in 16 subjects, omeprazole (20 mg daily) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of rilpivirine (150 mg daily) by 40%, 40%, and 33%, respectively. The Cmax and AUC of omeprazole decreased by 14% and 14%, respectively.(1) In a study in 24 subjects, famotidine (40 mg single dose) administered 12 hours before a single dose of rilpivirine (150 mg) had no significant effect on rilpivirine Cmax or AUC.(1) In a study in 23 subjects, famotidine (40 mg single dose) administered 2 hours before a single dose of rilpivirine (150 mg) decreased the rilpivirine Cmax and AUC by 85% and 76%, respectively.(1) In a study in 24 subjects, famotidine (40 mg single dose) administered 4 hours after a single dose of rilpivirine (150 mg) increased the rilpivirine Cmax and AUC by 21% and 13%, respectively.(1) |
COMPLERA, EDURANT, EDURANT PED, EMTRICITABINE-RILPIVIRNE-TENOF, ODEFSEY |
| Rivaroxaban/Selected P-gp and Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Amiodarone, azithromycin, brodalumab, chloramphenicol, cimetidine, cyclosporine, felodipine, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, hydroquinidine, ivacaftor, nilotinib, piperine, pirtobrutinib, quinidine, ranolazine, simeprevir, ticagrelor and tolvaptan may inhibit the metabolism of rivaroxaban by CYP3A4 and by P-glycoprotein.(1,2) CLINICAL EFFECTS: Concurrent use of an agent that is both an inhibitor of P-gp and a weak inhibitor of CYP3A4 may result in elevated levels of and clinical effects of rivaroxaban, including an increased risk of bleeding, in patients with decreased renal function.(1,2) PREDISPOSING FACTORS: Patients with decreased renal function (CrCL of 15 ml/min to 80 ml/min) may be predisposed to this interaction.(1) The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: The US manufacturer states no precautions are necessary with the concurrent use of these agents and rivaroxaban in patients with normal renal function.(1) It would be prudent to closely monitor concurrent use in patients with reduced renal function (CrCL of 15 ml/min to 80 ml/min). If concurrent therapy is warranted, monitor patients receiving concurrent therapy for signs of blood loss, including decreased hemoglobin, hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. INR, aPTT) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. DISCUSSION: Clarithromycin (500 mg twice daily) increased the area-under-curve (AUC) and maximum concentration (Cmax) of a single dose of rivaroxaban by 50% and 40%, respectively.(1,2) Erythromycin (500 mg three times daily) increased the AUC and Cmax of a single dose of rivaroxaban by 30% and 30%, respectively.(1-3) In patients with mild renal impairment (CrCl of 50 ml/min to 79 ml/min) who were receiving erythromycin, rivaroxaban levels were increased 76% when compared to administration of rivaroxaban in patients with normal renal function receiving rivaroxaban alone. In patients with moderate renal impairment (CrCl of 30 ml/min to 49 ml/min) who were receiving erythromycin, rivaroxaban levels were increased 99% when compared to administration of rivaroxaban in patients with normal renal function receiving rivaroxaban alone.(1) Fluconazole increased the AUC and Cmax of a single dose of rivaroxaban by 40%% and 30%, respectively.(1) These changes are not expected to be clinically significant in patients with normal renal function.(1,2) In a case report, an 88-year-old woman with renal impairment on rivaroxaban presented with an elevated INR of 2.5 and a rivaroxaban peak plasma concentration above the upper limit of detection at >800 mcg/L (therapeutic range 58-211 mcg/L). Nothing in her medical history suggested a reason for supratherapeutic rivaroxaban levels except for a 7-week amiodarone regimen that was discontinued 3 weeks prior. This suggests the potential for amiodarone to persist in the body weeks after its use and precipitate drug-drug interactions.(4) A retrospective cohort study examined 24,943 patients aged 66 years and older with concurrent therapy of an anticoagulant, either rivaroxaban (40.0%), apixaban (31.9%), or dabigatran (28.1%), with either azithromycin or clarithromycin. The primary outcome of hospital admission with major hemorrhage within 30 days on concurrent therapy was higher in patients on clarithromycin (0.77%) compared to azithromycin (0.43%) with an adjusted hazard ratio of 1.71 (95% CI, 1.20-2.45). In a self-controlled case series, 744 major hemorrhage events were identified among 647 unique individuals taking anticoagulants who were exposed to clarithromycin. The rate of events that occurred during clarithromycin use had a significant rate ratio of 1.44 (95% CI, 1.08-1.92).(5) A propensity matched cohort evaluated the concurrent use of combined P-gp and moderate CYP3A4 inhibitors with apixaban or rivaroxaban. Combined inhibitors included amiodarone, diltiazem, erythromycin, dronedarone, and verapamil. Bleeding occurred in 26.4% of patients in the inhibitor group compared to 18.4% in the control group (hazard ratio 1.8; 95% CI 1.19-2.73; p=0.006). Although not statistically significant, patients in the inhibitor group also had a higher rate of major bleeding (15% vs 10.3%) and minor bleeding (8.9% vs 5.2%), respectively.(6) A summary of pharmacokinetic interactions with rivaroxaban and amiodarone concluded that concurrent use should be avoided if CrCl < 80 ml/min.(7) A prospective cohort study of 174 patients evaluated the concurrent use of rivaroxaban and amiodarone. The combination of rivaroxaban and amiodarone was associated with a higher incidence of bleeding events (p=0.041; HR=2.83, 95% CI 1.05-7.66) and clinically relevant non-major bleeding (p=0.021; HR=3.65, 95% CI 1.21-10.94). Concurrent use of amiodarone and rivaroxaban in non-valvular atrial fibrillation patients was an independent risk factor for increased risk of bleeding (p=0.044; OR 2.871, 95% CI 1.028-8.023).(8) P-gp and weak CYP3A4 inhibitors linked to this monograph are: amiodarone, azithromycin, belumosudil, brodalumab, chloramphenicol, cimetidine, cyclosporine, daridorexant, diosmin, flibanserin, fostamatinib, glecaprevir/pibrentasvir, hydroquinidine, istradefylline, ivacaftor, mavorixafor, nilotinib, piperine, pirtobrutinib, quinidine, ranolazine, simeprevir and tolvaptan.(9,10) |
RIVAROXABAN, XARELTO |
| Citalopram (Less than or Equal To 20 mg)/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Citalopram is primarily metabolized by the CYP2C19 isoenzyme.(1) CLINICAL EFFECTS: Concurrent use of an agent that inhibits CYP2C19 may result in elevated levels of and toxicity from citalopram, including including risks for serotonin syndrome or prolongation of the QTc interval.(1-5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(5) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, advanced age, poor metabolizer status at CYP2C19, or higher blood concentrations of citalopram.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,5) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. PATIENT MANAGEMENT: The dose of citalopram should be limited to 20 mg in patients receiving concurrent therapy with an inhibitor of CYP2C19.(1,4) Evaluate the patient for other drugs, diseases and conditions which increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, hypocalcemia, hypomagnesemia, discontinue other QT prolonging drugs) when possible.(1,2) Weigh the specific benefits versus risks for each patient. The US manufacturer recommends ECG monitoring for citalopram patients with congestive heart failure, bradyarrhythmias, taking concomitant QT prolonging medications or receiving concurrent therapy.(4) Citalopram should be discontinued in patients with persistent QTc measurements greater than 500 ms.(2) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: Concurrent use of citalopram (40 mg daily) and cimetidine (400 mg twice daily) for 8 days increased the maximum concentration (Cmax) and area-under-curve (AUC) of citalopram by 39% and 43%, respectively.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, and tecovirimat.(7,8) |
CELEXA, CITALOPRAM HBR |
| Deferiprone/Aluminum, Iron, Zinc SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Deferiprone chelates polyvalent cations such as aluminum, iron, and zinc.(1) CLINICAL EFFECTS: Deferiprone chelation with oral aluminum, iron or zinc containing products in the gastrointestinal tract may decrease the amount of free deferiprone available for systemic iron chelation. Zinc supplements prescribed to counteract deferiprone-induced zinc deficiency may not be effective if taken near time of deferiprone administration. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer recommends at least a four hour interval between deferiprone dose and administration of aluminum, iron or zinc containing medications or supplements.(1) Avoid use of iron-containing vitamins or nutritional supplements in patients who require chelation therapy for iron overload. DISCUSSION: The US manufacturer has not studied this interaction. The recommendation to separate deferiprone and polyvalent cation doses by at least four hours is based upon the deferiprone mechanism of action.(1) |
DEFERIPRONE, DEFERIPRONE (3 TIMES A DAY), FERRIPROX, FERRIPROX (2 TIMES A DAY), FERRIPROX (3 TIMES A DAY) |
| Selected Oral Quinolones/Selected Oral Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum, iron, lanthanum, magnesium, and zinc may form chelation compounds with the quinolones.(1-23) CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, iron, lanthanum, magnesium, and/or zinc close to the administration time of an oral quinolone may result in decreased absorption and clinical effectiveness of the quinolone PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If possible, avoid concurrent therapy with quinolones and cation-containing products. If it is necessary to administer these agents concurrently, follow the manufacturers' recommendations regarding timing of administration of the quinolone and cation-containing products. Manufacturer recommendations regarding the separation of administration times of quinolones and products containing aluminum, iron, lanthanum, magnesium, and/or zinc vary: ---Do not give gatifloxacin for at least 4 hours before oral cations(1) ---Do not give gemifloxacin for at least 2 hours before or 3 hours after oral cations.(2) ---Do not give lomefloxacin for at least 2 hours before or 4 hours after oral cations.(3) ---Do not give moxifloxacin for at least 4 hours before or 8 hours after oral cations.(4) ---Do not give trovafloxacin for at least 2 hours before or after oral cations.(5) ---Do not give prulifloxacin for at least 2 hours before or 4 hours after oral cations.(23) The US manufacturer of lanthanum recommends that quinolones be taken at least 1 hour before or 4 hours after lanthanum;(6) however, it would be prudent to follow the specific quinolone manufacturers' recommendations regarding concurrent administration of cations. For quinolones not listed above, separate their administration from oral cations by as much time as feasible. DISCUSSION: Magnesium and aluminum compounds have been shown to form chelation compounds with quinolone antibiotics, resulting in decreased absorption of the quinolone.(1-22) Treatment failures during concurrent use of cations and gatifloxacin(7) and pefloxacin(8) have been reported. In a study in 24 healthy subjects, administration of an aluminum-magnesium hydroxide antacid simultaneously, 2 hours before, or 2 hours after decreased the area-under-curve (AUC) of a single dose of gatifloxacin (400 mg) by 42%, 64%, or 18%, respectively. There were no affects on gatifloxacin AUC when the antacid was administered 4 hours after gatifloxacin.(9) In a study in 16 healthy males, administration of an aluminum-magnesium hydroxide antacid 10 minutes before or 3 hours after a single dose of gemifloxacin (320 mg) decreased the gemifloxacin AUC by 85% and 15%, respectively. There was no affect when the antacid was administered 2 hours after gemifloxacin.(10) In a study in 16 subjects, simultaneous administration of calcium carbonate decreased the maximum concentration (Cmax) and AUC of a single dose of gemifloxacin (320 mg) by 17% and 21%, respectively. There was no effect of calcium carbonate when administered either 2 hours before or after gemifloxacin.(11) In a study in 27 healthy males, the administration of ferrous sulfate (325 mg) 3 hours before a single dose of gemifloxacin (320 mg) decreased the Cmax and AUC of gemifloxacin by 20% and 11%, respectively. There were no effects when ferrous sulfate was administered 2 hours after gemifloxacin.(12) In a study in 8 healthy subjects, ferrous sulfate (100 mg elemental iron) decreased the Cmax and AUC of a single dose of lomefloxacin by 26% and 13%, respectively. There were no effects with concurrent calcium carbonate (500 mg calcium).(13) Magnesium- and aluminum-containing antacids have been shown to decrease the bioavailability of lomefloxacin by 40%.(14) Administration of moxifloxacin 2 hours before, simultaneously, or 4 hours after a magnesium- and aluminum-containing antacid decreased moxifloxacin AUC by 26%, 60%, and 23%, respectively.(15) Simultaneous administration of moxifloxacin and ferrous sulfate (100 mg) decreased the area-under-curve (AUC) and maximum concentration (Cmax) of moxifloxacin by 39% and 59%, respectively.(16) Concurrent administration of calcium had no affect on moxifloxacin pharmacokinetics.(17) In a study in 10 healthy subjects, an aluminum-magnesium hydroxide antacid decreased the bioavailability of pefloxacin (400 mg) by 44.4%.(18) The administration of an antacid containing aluminum hydroxide and magnesium hydroxide 5 minutes before rufloxacin decreased rufloxacin levels by 36%. Administration of the antacid 4 hours after rufloxacin decreased rufloxacin levels by 13%.(19) Magnesium- and aluminum-containing antacids have been shown to decrease the bioavailability of temafloxacin by 40%.(20) Aluminum hydroxide has been shown to decrease the bioavailability of tosufloxacin by 31.6%.(21) Administration of an antacid containing aluminum hydroxide and magnesium hydroxide 30 minutes before trovafloxacin decreased trovafloxacin levels by 66%.(22) One or more of the drug pairs linked to this monograph have been included in a list of interactions that could be considered for classification as "non-interruptive" in EHR systems. This DDI subset was vetted by an expert panel commissioned by the U.S. Office of the National Coordinator (ONC) for Health Information Technology. |
GATIFLOXACIN SESQUIHYDRATE, MOXIFLOXACIN HCL |
| Selected Cephalosporins/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Absorption of oral cefuroxime may be reduced in patients receiving concomitant treatment with acid reducing agents.(1,2) CLINICAL EFFECTS: Antibiotic efficacy against organisms with a high minimum inhibitory concentration (MIC) to cefuroxime could be decreased. PREDISPOSING FACTORS: Taking cefuroxime on an empty stomach magnifies this effect. PATIENT MANAGEMENT: Separate the administration of cefuroxime by at least 1-2 hours after administration of antacids. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. Since concurrent use of H2 antagonists and proton pump inhibitors (PPIs) in patients taking cefuroxime should be avoided, these would not be alternatives to antacids in these patients. DISCUSSION: In a study performed prior to the introduction of PPIs, administration of ranitidine 300 mg and sodium bicarbonate followed by cefuroxime taken on a empty stomach lowered both Cmax and AUC of cefuroxime by approximately 40 per cent compared with administration of cefuroxime alone on an empty stomach. Postprandial administration of cefuroxime in subjects taking ranitidine was similar to that of subjects taking cefuroxime on an empty stomach.(2) |
CEFUROXIME |
| Elvitegravir/Selected Oral Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The exact mechanism is unknown, but aluminum, calcium, iron, magnesium, sucralfate, and zinc may bind to elvitegravir in GI tract. CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, magnesium, and/or sucralfate may result in decreased levels and effectiveness of elvitegravir, as well as the development of resistance.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Separate the administration of elvitegravir and products containing aluminum, calcium, iron, magnesium, and/or sucralfate by at least 2 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: Administration of an antacid (exact formulation not stated) 2 hours before elvitegravir (50 mg) decreased the maximum concentration (Cmax), area-under-curve (AUC), or minimum concentration (Cmin) of elvitegravir by 18%, 15%, and 10%, respectively.(1) Administration of an antacid 2 hours after elvitegravir (50 mg) decreased the Cmax, AUC, or Cmin of elvitegravir by 21%, 20%, and 20%, respectively.(1) Administration of an antacid 4 hours before elvitegravir (50 mg) decreased the Cmax and AUC of elvitegravir by 5%, and 4%, respectively.(1) Administration of an antacid 4 hours before elvitegravir (50 mg) decreased both the Cmax and AUC of elvitegravir by 2%.(1) |
GENVOYA, STRIBILD |
| Escitalopram (Greater Than 15 mg)/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: At lower systemic concentrations, escitalopram is primarily metabolized by CYP2C19; at higher concentrations is also metabolized by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of an agent which significantly inhibits CYP2C19, or which inhibits both CYP2C19 and CYP3A4 may result in elevated concentrations and toxicity from escitalopram, including risks for serotonin syndrome or prolongation of the QTc interval.(1,5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(3) PREDISPOSING FACTORS: The risk of QT prolongation may be increased in patients with congenital long QT syndrome, cardiovascular disease (e.g. heart failure, myocardial infarction), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female sex, advanced age, poor metabolizer status at CYP2C19, concurrent use of more than one agent known to cause QT prolongation, or with higher blood concentrations of escitalopram.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,3) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. PATIENT MANAGEMENT: Evaluate patient for other drugs, diseases and conditions which may further increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, discontinue other QT prolonging drugs) when possible.(2,3) It would be prudent to limit the escitalopram dose to 10 mg daily in patients with QT prolonging risk factors who also receive concurrent therapy with selected CYP2C19 inhibitors.(5) Weigh the specific benefits versus risks for each patient. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: A thorough QT study evaluating escitalopram 10 mg or 30 mg once daily was conducted; a change of 10 msec for upper bound of the 95% confidence level is the threshold for regulatory concern. In this study, changes to the upper bound of the 95% confidence interval were 6.4 msec and 12.6 msec for the 10 mg and supratherapeutic 30 mg dose respectively. The Cmax for 30 mg was 1.7-fold higher than the Cmax for the maximum recommended escitalopram dose of 20 mg. Systemic exposure at the 30 mg dose was similar to expected steady state concentrations in 2C19 poor metabolizers following a 20 mg escitalopram dose.(1) In an interaction study, 30 mg of omeprazole, an irreversible inhibitor of CYP2C19 was administered daily for 6 days. On day 5 a single dose of escitalopram 20 mg was also administered; the area-under-curve (AUC) of escitalopram was increased by 50%. Manufacturer prescribing information recommends a maximum citalopram dose of 20mg daily in patients receiving CYP2C19 inhibitors.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, tecovirimat, and tipranavir.(4) |
ESCITALOPRAM OXALATE, LEXAPRO |
| Afatinib/P-glycoprotein (P-gp) Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of P-glycoprotein (P-gp) may increase the absorption of afatinib.(1) CLINICAL EFFECTS: The concurrent administration of afatinib with an inhibitor of P-glycoprotein may result in elevated levels of afatinib and signs of toxicity. These signs may include but are not limited to worsening diarrhea, stomatitis, skin rash/exfoliation/bullae or paronychia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of afatinib states the afatinib dose should be reduced by 10 mg if the addition of a P-glycoprotein inhibitor is not tolerated.(1) If afatinib dose was reduced due to addition of a P-gp inhibitor, resume the previous dose after the P-gp inhibitor is discontinued.(1) The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to afatinib.(2) DISCUSSION: A drug interaction study evaluated the effects of ritonavir 200 mg twice daily on afatinib exposure. Administration of ritonavir 1 hour before afatinib administration increased systemic exposure by 48%. Afatinib exposure was not changed when ritonavir was administered simultaneously with or 6 hours after afatinib dose.(1) P-glycoprotein inhibitors linked to this monograph are: amiodarone, asunaprevir, azithromycin, belumosudil, carvedilol, cimetidine, clarithromycin, cobicistat, cyclosporine, danicopan, daridorexant, diosmin, dronedarone, erythromycin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, isavuconazonium, itraconazole, ivacaftor, josamycin, ketoconazole, lapatinib, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, propafenone, quinidine, ranolazine, ritonavir, saquinavir, sofosbuvir/velpatasvir/voxilaprevir, telaprevir, tepotinib, tezacaftor, tucatinib, valbenazine, vemurafenib, verapamil, vimseltinib and voclosporin.(1-3) |
GILOTRIF |
| Dolutegravir/Selected Oral Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum, calcium, iron, lanthanum, magnesium, sucralfate, and zinc may form chelation compounds with dolutegravir.(1) CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or sucralfate close to the administration time of dolutegravir may result in decreased absorption and clinical effectiveness of dolutegravir.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If possible, avoid concurrent therapy with dolutegravir and cation-containing products. If it is necessary to use these agents concurrently, dolutegravir should be administered 2 hours before or 6 hours after taking these medications.(1) Alternatively, dolutegravir and supplements containing calcium or iron can be taken together with food.(1) DISCUSSION: In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) simultaneously with dolutegravir (50 mg single dose) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of dolutegravir by 72%, 74%, and 74%, respectively.(1) In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) 2 hours after dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 18%, 26%, and 30%, respectively.(1) In a study in 16 subjects, the administration of a multiple vitamin (One-A-Day) simultaneously with dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 35%, 33%, and 32%, respectively.(1) |
DOVATO, TIVICAY, TIVICAY PD, TRIUMEQ, TRIUMEQ PD |
| Riociguat/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The mechanism of interaction is not clear. Increased gastric pH is thought to decrease riociguat solubility and absorption.(1) CLINICAL EFFECTS: Simultaneous administration of riociguat with an antacid may result in decreased levels and effectiveness of riociguat.(1-2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Separate the administration of antacids and riociguat by at least 1 hour.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: Administration of 10 mL of an aluminum hydroxide-magnesium hydroxide containing antacid decreased the area-under-curve (AUC)and maximum concentration (Cmax)of riociguat by 34% and 56% respectively.(1) |
ADEMPAS |
| Ledipasvir; Velpatasvir/Antacids; H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of ledipasvir and velpatasvir is pH dependent. Higher gastric pH leads to lower solubility which may reduce ledipasvir and velpatasvir's absorption.(1-3) CLINICAL EFFECTS: Administration of antacids and H2 antagonists may reduce the bioavailability of ledipasvir and velpatasvir, leading to decreased systemic levels and effectiveness.(1-3) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: In order to assure systemic absorption and maximal effectiveness from use of this Hepatitis C treatment, counsel patient to separate products containing ledipasvir or velpatasvir from antacid administration by 4 hours.(1-3) H2 antagonists may be administered simultaneously or 12 hours apart from products containing ledipasvir or velpatasvir at a dose that does not exceed doses comparable to famotidine 40 mg twice daily (or a total daily dose comparable to famotidine 80 mg).(1-3) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: In an interaction study, famotidine 40 mg, given with or 12 hours after a ledipasvir-sofosbuvir dose did not have significant effects on ledipasvir-sofosbuvir exposure.(1) In an interaction study, famotidine 40 mg, given with or 12 hours prior to a velpatasvir-sofosbuvir dose did not have a significant effect on velpatasvir-sofosbuvir exposure.(2) In an interaction study, famotidine (dosage not stated) did not have a significant effect on the pharmacokinetic of sofosbuvir, velpatasvir, or voxilaprevir.(3) |
EPCLUSA, HARVONI, LEDIPASVIR-SOFOSBUVIR, SOFOSBUVIR-VELPATASVIR, VOSEVI |
| Nintedanib/Dual CYP3A4 & P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Nintedanib is a substrate for the P-glycoprotein (P-gp) transporter and is metabolized to a minor extent by CYP3A4. CLINICAL EFFECTS: Concurrent use of an agent that is both an inhibitor of P-gp and CYP3A4 may result in elevated levels of and clinical effects of nintedanib. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of nintedanib recommends close monitoring for nintedanib patients receiving drugs which are both P-gp and CYP3A4 inhibitors. In an interaction study ketoconazole increased exposure to nintedanib by 60%. Nintedanib therapy may need to be interrupted or the dose may need to be reduced.(1) DISCUSSION: In an interaction study coadministration with ketoconazole, a P-gp and CYP3A4 inhibitor, increased nintedanib exposure (area-under-curve, AUC) and maximum concentration (Cmax) by 1.61-fold and 1.83 fold respectively.(1) Strong CYP3A4 & P-gp inhibitors include: adagrasib, boceprevir, clarithromycin, cobicistat, grapefruit, indinavir, itraconazole, josamycin, ketoconazole, levoketoconazole, lonafarnib, lopinavir, mibefradil, mifepristone, nefazodone, nelfinavir, nirmatrelvir, paritaprevir, posaconazole, ritonavir, saquinavir, telaprevir, telithromycin, tipranavir, and tucatinib. Moderate CYP3A4 & P-gp inhibitors include: conivaptan, diltiazem, dronedarone, erythromycin, fluvoxamine, isavuconazonium, schisandra, and verapamil. Weak CYP3A4 & P-gp inhibitors include: amiodarone, azithromycin, cimetidine, cyclosporine, daclatasvir, daridorexant, diosmin, flibanserin, fluvoxamine, fostamatinib, glecaprevir/pibrentasvir, ivacaftor, lapatinib, mavorixafor, and ranolazine.(2) |
OFEV |
| Cholic Acid/Aluminum-Based Antacids; Bile Acid Sequestrants SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum-based antacids and bile acid sequestrants may decrease the gastrointestinal absorption of cholic acid.(1) CLINICAL EFFECTS: Simultaneous administration of an aluminum-based antacid or a bile acid sequestrant may result in decreased absorption and effectiveness of cholic acid.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: For maximal bioavailability in patients receiving both medications, administer cholic acid at least 1 hour before or 4-6 hours after (or as great an interval as possible) a bile acid sequestrant or aluminum-based antacid.(1) DISCUSSION: Aluminum-based antacids have been shown to adsorb cholic acid in vitro. Bile acid sequestrants reduce bile acid absorption.(1) |
CHOLBAM |
| Edoxaban (Greater Than 30 mg)/Select P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Edoxaban is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease renal tubular elimination of edoxaban.(1,2) CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of edoxaban which may increase the risk for bleeding.(1,2) PREDISPOSING FACTORS: Bleeding risk may be increased in patients with creatinine clearance below 50 mL per minute(1-4). Use of multiple agents which increase edoxaban exposure or affect hemostasis would be expected to increase the risk for bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: Management recommendations between approving regulatory agencies (FDA or European Medicines Agency, EMA) are conflicting. EMA approved prescribing information specifically states that dosage adjustments are not required solely for concomitant use with amiodarone, quinidine, or verapamil regardless of indication.(3,4) Potential interactions with azithromycin, clarithromycin, or oral itraconazole are not described.(3) FDA approved prescribing recommendations for edoxaban are indication specific:(2) - For prevention of stroke or embolic events due to nonvalvular atrial fibrillation, no edoxaban dose adjustments are recommended during concomitant therapy with P-glycoprotein inhibitors. - For treatment of deep vein thrombosis (DVT) or pulmonary embolism (PE), the edoxaban dose should be reduced to 30 mg daily during concomitant use with azithromycin, clarithromycin, oral itraconazole, quinidine or verapamil. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to edoxaban.(6) Monitor patients receiving anticoagulant therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. anti Factor Xa inhibition) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. Discontinue edoxaban in patients with active bleeding. DISCUSSION: Edoxaban in vivo interaction studies have been performed for quinidine and verapamil. In vivo interaction studies have not been conducted for the remaining P-gp inhibitors linked to this monograph.(1,4) In an interaction study, the effect of repeat administration of quinidine (300 mg TID) on a single oral dose of edoxaban 60 mg was evaluated in healthy subjects. Both peak (Cmax) and total systemic exposure (AUC) to edoxaban and to the active M4 metabolite increased approximately 1.75-fold.(1) In an interaction study, the effect of repeat administration of verapamil (240 mg Verapamil SR Tablets (Calan SR) QD for 11 Days) on a single oral dose of edoxaban 60 mg on the morning of Day 10 was evaluated in healthy subjects. Total and peak systemic exposure to edoxaban increased 1.53-fold and 1.53-fold, respectively. Total and peak systemic exposure to the active M4 metabolite increased 1.31-fold and 1.28-fold, respectively.(1) Based upon the above results, patients in the DVT/PE trial had a 50% dose reduction (from 60 mg to 30 mg) during concomitant therapy with P-glycoprotein inhibitors. Approximately 0.5% of these patients required a dose reduction solely due to P-gp inhibitor use. This low rate of concurrent therapy was too small to allow for detailed statistical evaluation. Almost all of these patients were receiving quinidine or verapamil. In these patients, both trough edoxaban concentrations (Ctrough) used to evaluate bleeding risk, and total edoxaban exposure (AUC or area-under-curve) used to evaluate treatment efficacy, were lower than patients who did not require any edoxaban dose adjustment. In this DVT/PE comparator trial, subgroup analysis revealed that warfarin had numerically better efficacy than edoxaban in patients receiving P-gp inhibitors. Based upon the overall lower exposure to edoxaban in P-gp dose adjusted subjects, both EMA and FDA Office of Clinical Pharmacology (OCP) concluded that the edoxaban 50% dose reduction overcorrected for the difference in exposure.(1,4) Consequently, EMA recommended no edoxaban dose adjustments for patients receiving concomitant therapy with quinidine or verapamil.(3,4) A summary of pharmacokinetic interactions with edoxaban and verapamil concluded that if concurrent use is considered safe.(7) P-gp inhibitors linked to this interaction are: amiodarone, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, oral itraconazole, indinavir, ivacaftor, josamycin, ledipasvir, lonafarnib, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil, vimseltinib, and voclosporin.(8) |
SAVAYSA |
| Selected Kinase Inhibitors/H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The solubility of dacomitinib,(1) erlotinib,(2) gefitinib,(3) and nilotinib(4) is pH dependent. Changes in gastric pH from H2 antagonists may decrease the absorption of dacomitinib,(1) erlotinib,(2) gefitinib,(3) and nilotinib(4). CLINICAL EFFECTS: Use of H2 antagonists may result in decreased levels and effectiveness of dacomitinib,(1) erlotinib,(2) gefitinib,(3) and nilotinib(4). PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Consider the use of short-acting antacids in patients taking dacomitinib,(1) erlotinib,(2) gefitinib,(3) and nilotinib(4). If antacids are used, separate the administration times by several hours(1-7) but at least 2 hours for bosutinib,(1) and nilotinib,(4) and 6 hours for gefitinib.(3) If H2 antagonist therapy is required with dacomitinib, dacomitinib must be given once daily 10 hours after the H2 blocker and 6 hours before the next dose of the H2 blocker.(1) If H2 antagonist therapy is required with erlotinib or nilotinib, the kinase inhibitor must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker.(2-4) If H2 antagonist therapy is required with gefitinib, gefitinib should be given at least 6 hours before or after the H2 antagonist.(3) Avoid the use of proton pump inhibitors (PPIs) in patients receiving treatment dacomitinib,(1) erlotinib,(2) gefitinib,(3) and nilotinib(4). DISCUSSION: In a study, concurrent rabeprazole decreased the Cmax and AUC of dacomitinib by 51% and 39%, respectively.(1) In a study, concurrent omeprazole decreased the AUC and Cmax of erlotinib by 46% and 61%, respectively.(2) In a study, administration of erlotinib two hours after a dose of ranitidine (300 mg), erlotinib AUC and Cmax decreased by 33% and 54%, respectively. Administration of erlotinib 10 hours after and two hours before ranitidine (150 mg twice daily), erlotinib AUC and Cmax decreased by 15% and 17%, respectively.(2) In a case report, a patient that was given erlotinib (150 mg daily,) with algeldrate/magnesium hydroxide (800/400 mg four times daily 4 hours before or 2 hours after erlotinib) did not see a significant reduction in serum trough concentrations of erlotinib. When the patient was switched to intravenous pantoprazole via continuous infusion (8 mg per hour), serum erlotinib levels decreased significantly below minimal trough concentrations for effective tyrosine kinase inhibition. When the patient was switched to oral pantoprazole (40 mg twice daily), serum trough levels of erlotinib returned to therapeutic levels.(5) In a study in 22 healthy subjects, pretreatment with esomeprazole (40 mg daily), decreased the Cmax and AUC of a single dose of nilotinib (400 mg) by 27% and 34%, respectively.(4,7) Increasing the dosage of nilotinib or separating the administration time of nilotinib and the proton pump inhibitor is not expected to eliminate the interaction.(4) There were no significant changes in nilotinib pharmacokinetics when famotidine was administered 10 hours before or 2 hours after nilotinib.(4) There were no significant changes in nilotinib pharmacokinetics when an antacid (aluminum hydroxide/magnesium hydroxide/simethicone) was administered 2 hours before or after nilotinib.(4) |
DANZITEN, ERLOTINIB HCL, GEFITINIB, IRESSA, NILOTINIB HCL, NILOTINIB TARTRATE, TASIGNA, VIZIMPRO |
| Dolutegravir-Rilpivirine/Selected Oral Cations; Antacids; H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum, calcium, iron, lanthanum, magnesium, sucralfate, and zinc may form chelation compounds with dolutegravir.(1) Rilpivirine requires an acidic medium for absorption. Antacid or H2 antagonist induced decrease in gastric pH may result in decrease in rilpivirine absorption.(1) CLINICAL EFFECTS: Simultaneous administration or administration of products containing aluminum, calcium, iron, lanthanum, magnesium, and/or sucralfate close to the administration time of dolutegravir may result in decreased absorption and clinical effectiveness of dolutegravir.(1) Simultaneous administration of an antacid or a H2 antagonist may result in decreased levels and effectiveness of rilpivirine, as well as the development of resistance.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If possible, avoid concurrent therapy with dolutegravir-rilpivirine and cation-containing products. If it is necessary to use these agents concurrently, dolutegravir-rilpivirine should be administered 4 hours before or 6 hours after taking these medications.(1) Alternatively, dolutegravir-rilpivirine and supplements containing calcium or iron can be taken together with food.(1) In patients maintained on dolutegravir-rilpivirine, administer dolutegravir-rilpivirine at least 4 hours before or 6 hours after antacids .(1) In patients maintained on dolutegravir-rilpivirine, administer dolutegravir-rilpivirine at least 4 hours before or 12 hours after H2 antagonists.(1) Concurrent use of proton pump inhibitors will dolutegravir-rilpivirine is contraindicated.(1) DISCUSSION: In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) simultaneously with dolutegravir (50 mg single dose) decreased the maximum concentration (Cmax), area-under-curve (AUC), and minimum concentration (Cmin) of dolutegravir by 72%, 74%, and 74%, respectively.(1) In a study in 16 subjects, the administration of an antacid (Maalox - aluminum and magnesium hydroxide) 2 hours after dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 18%, 26%, and 30%, respectively.(1) In a study in 16 subjects, the administration of a multiple vitamin (One-A-Day) simultaneously with dolutegravir (50 mg single dose) decreased dolutegravir Cmax, AUC, and Cmin by 35%, 33%, and 32%, respectively.(1) In a study in 16 subjects, omeprazole (20 mg daily) decreased the Cmax, AUC, and Cmin of rilpivirine (150 mg daily) by 40%, 40%, and 33%, respectively. The Cmax and AUC of omeprazole decreased by 14% and 14%, respectively.(1) In a study in 24 subjects, famotidine (40 mg single dose) administered 12 hours before a single dose of rilpivirine (150 mg) had no significant effect on rilpivirine Cmax or AUC.(1) In a study in 23 subjects, famotidine (40 mg single dose) administered 2 hours before a single dose of rilpivirine (150 mg) decreased the rilpivirine Cmax and AUC by 85% and 76%, respectively.(1) In a study in 24 subjects, famotidine (40 mg single dose) administered 4 hours before a single dose of rilpivirine (150 mg) increased the rilpivirine Cmax and AUC by 21% and 13%, respectively.(1) |
JULUCA |
| Bictegravir/Polyvalent Cations; Sucralfate SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Polyvalent cations and sucralfate may bind to bictegravir in the GI tract, preventing its absorption.(1) CLINICAL EFFECTS: Polyvalent cations and sucralfate may reduce levels and clinical effectiveness of bictegravir.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Bictegravir must be taken 2 hours before or 6 hours after polyvalent cations or sucralfate. Medicines containing calcium can be taken together with bictegravir if taken with food.(1) Some vitamin preparations may contain sufficient quantities of polyvalent cations to interact as well. DISCUSSION: Simultaneous administration of aluminum and magnesium hydroxide (20 ml) in a fasted state with bictegravir (50 mg single dose) decreased bictegravir maximum concentration (Cmax) and area-under-curve (AUC) by 80% and 79%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours after bictegravir (50 mg single dose) in a fasted state decreased bictegravir Cmax and AUC by 7% and 13%, respectively.(1) Administration of aluminum and magnesium hydroxide (20 ml) 2 hours before bictegravir (50 mg single dose) in a fasted state decreased bictegravir Cmax and AUC by 58% and 52%, respectively.(1) Simultaneous administration of aluminum and magnesium hydroxide (20 ml) in a fed state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 49% and 47%, respectively.(1) Simultaneous administration of calcium carbonate (1200 mg single dose) in a fasted state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 42% and 33%, respectively.(1) Simultaneous administration of calcium carbonate (1200 mg single dose) in a fed state with bictegravir (50 mg single dose) decreased bictegravir Cmax by 10% and increased AUC 3%, respectively.(1) Simultaneous administration of ferrous fumarate (324 mg single dose) in a fasted state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 71% and 63%, respectively.(1) Simultaneous administration of ferrous fumarate (324 mg single dose) in a fed state with bictegravir (50 mg single dose) decreased bictegravir Cmax and AUC by 25% and 16%, respectively.(1) |
BIKTARVY |
| Edoxaban (Less Than or Equal To 30 mg)/Select P-gp Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Edoxaban is a substrate for P-glycoprotein (P-gp). Inhibitors of P-gp may increase intestinal absorption and decrease renal tubular elimination of edoxaban.(1,2) CLINICAL EFFECTS: Concurrent use with selected P-gp inhibitors may result in higher systemic concentrations of edoxaban which may increase the risk for bleeding.(1,2) PREDISPOSING FACTORS: Bleeding risk may be increased in patients with creatinine clearance below 50 mL per minute(1-4). Use of multiple agents which increase edoxaban exposure or affect hemostasis would be expected to increase the risk for bleeding. The risk for bleeding episodes may be greater in patients with disease-associated factors (e.g. thrombocytopenia). Drug associated risk factors include concurrent use of multiple drugs which inhibit anticoagulant/antiplatelet metabolism and/or have an inherent risk for bleeding (e.g. NSAIDs). PATIENT MANAGEMENT: Management recommendations between approving regulatory agencies (FDA or European Medicines Agency, EMA) are conflicting. EMA approved prescribing information specifically states that dosage adjustments are not required solely for concomitant use with amiodarone, quinidine, or verapamil regardless of indication.(3,4) Potential interactions with azithromycin, clarithromycin, or oral itraconazole are not described.(3) FDA approved prescribing recommendations for edoxaban are indication specific:(2) - For prevention of stroke or embolic events due to nonvalvular atrial fibrillation, no edoxaban dose adjustments are recommended during concomitant therapy with P-glycoprotein inhibitors. - For treatment of deep vein thrombosis (DVT) or pulmonary embolism (PE), the edoxaban dose should be reduced to 30 mg daily during concomitant use with azithromycin, clarithromycin, oral itraconazole, quinidine or verapamil. The manufacturer of vimseltinib states concurrent use with P-gp substrates should be avoided. If concurrent use cannot be avoided, take vimseltinib at least 4 hours prior to edoxaban.(6) Monitor patients receiving anticoagulant therapy for signs of blood loss, including decreased hemoglobin and/or hematocrit, fecal occult blood, and/or decreased blood pressure and promptly evaluate patients with any symptoms. When applicable, perform agent-specific laboratory test (e.g. anti Factor Xa inhibition) to monitor efficacy and safety of anticoagulation. Discontinue anticoagulation in patients with active pathologic bleeding. Instruct patients to report any signs and symptoms of bleeding, such as unusual bleeding from the gums or nose; unusual bruising; red or black, tarry stools; red, pink or dark brown urine; acute abdominal or joint pain and/or swelling. Discontinue edoxaban in patients with active bleeding. DISCUSSION: Edoxaban in vivo interaction studies have been performed for quinidine and verapamil. In vivo interaction studies have not been conducted for the remaining P-gp inhibitors linked to this monograph.(1,4) In an interaction study, the effect of repeat administration of quinidine (300 mg TID) on a single oral dose of edoxaban 60 mg was evaluated in healthy subjects. Both peak (Cmax) and total systemic exposure (AUC) to edoxaban and to the active M4 metabolite increased approximately 1.75-fold.(1) In an interaction study, the effect of repeat administration of verapamil (240 mg Verapamil SR Tablets (Calan SR) QD for 11 Days) on a single oral dose of edoxaban 60 mg on the morning of Day 10 was evaluated in healthy subjects. Total and peak systemic exposure to edoxaban increased 1.53-fold and 1.53-fold, respectively. Total and peak systemic exposure to the active M4 metabolite increased 1.31-fold and 1.28-fold, respectively.(1) Based upon the above results, patients in the DVT/PE trial had a 50% dose reduction (from 60 mg to 30 mg) during concomitant therapy with P-glycoprotein inhibitors. Approximately 0.5% of these patients required a dose reduction solely due to P-gp inhibitor use. This low rate of concurrent therapy was too small to allow for detailed statistical evaluation. Almost all of these patients were receiving quinidine or verapamil. In these patients, both trough edoxaban concentrations (Ctrough) used to evaluate bleeding risk, and total edoxaban exposure (AUC or area-under-curve) used to evaluate treatment efficacy, were lower than patients who did not require any edoxaban dose adjustment. In this DVT/PE comparator trial, subgroup analysis revealed that warfarin had numerically better efficacy than edoxaban in patients receiving P-gp inhibitors. Based upon the overall lower exposure to edoxaban in P-gp dose adjusted subjects, both EMA and FDA Office of Clinical Pharmacology (OCP) concluded that the edoxaban 50% dose reduction overcorrected for the difference in exposure.(1,4) Consequently, EMA recommended no edoxaban dose adjustments for patients receiving concomitant therapy with quinidine or verapamil.(3,4) A summary of pharmacokinetic interactions with edoxaban and verapamil concluded that if concurrent use is considered safe.(7) P-gp inhibitors linked to this interaction are: amiodarone, asunaprevir, azithromycin, belumosudil, capmatinib, carvedilol, cimetidine, clarithromycin, cobicistat, conivaptan, daclatasvir, danicopan, daridorexant, diltiazem, diosmin, flibanserin, fostamatinib, ginseng, glecaprevir/pibrentasvir, hydroquinidine, indinavir, oral itraconazole, ivacaftor, josamycin, ledipasvir, lonafarnib, mavorixafor, neratinib, osimertinib, pirtobrutinib, propafenone, quinidine, ranolazine, telaprevir, telithromycin, tezacaftor, tepotinib, tucatinib, valbenazine, velpatasvir, vemurafenib, verapamil vimseltinib, and voclosporin.(8) |
SAVAYSA |
| Escitalopram (Less Than or Equal To 15 mg)/Selected CYP2C19 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: At lower systemic concentrations, escitalopram is primarily metabolized by CYP2C19; at higher concentrations is also metabolized by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of an agent which significantly inhibits CYP2C19, or which inhibits both CYP2C19 and CYP3A4 may result in elevated concentrations and toxicity from escitalopram, including risks for serotonin syndrome or prolongation of the QTc interval.(1,5) Prolongation of the QT interval may result in life-threatening arrhythmias, including torsades de pointes.(2) Symptoms of serotonin syndrome may include tremor, agitation, diaphoresis, hyperreflexia, clonus, tachycardia, hyperthermia, and muscle rigidity.(3) PREDISPOSING FACTORS: The risk of QT prolongation may be increased in patients with congenital long QT syndrome, cardiovascular disease (e.g. heart failure, myocardial infarction), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female sex, advanced age, poor metabolizer status at CYP2C19, concurrent use of more than one agent known to cause QT prolongation, or with higher blood concentrations of escitalopram.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) Predisposing factors for serotonin-related adverse effects include use in the elderly, in patients with hepatic impairment, and in patients receiving multiple agents which increase central serotonin levels.(1,3) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. PATIENT MANAGEMENT: Evaluate patient for other drugs, diseases and conditions which may further increase risk for QT prolongation and correct risk factors (e.g. correct hypokalemia, discontinue other QT prolonging drugs) when possible.(2,3) It would be prudent to limit the escitalopram dose to 10 mg daily in patients with QT prolonging risk factors who also receive concurrent therapy with selected CYP2C19 inhibitors.(5) Weigh the specific benefits versus risks for each patient. If concurrent therapy is warranted, patients should be monitored for signs and symptoms of serotonin syndrome. Instruct patients to report muscle twitching, tremors, shivering and stiffness, fever, heavy sweating, heart palpitations, restlessness, confusion, agitation, trouble with coordination, or severe diarrhea. DISCUSSION: A thorough QT study evaluating escitalopram 10 mg or 30 mg once daily was conducted; a change of 10 msec for upper bound of the 95% confidence level is the threshold for regulatory concern. In this study, changes to the upper bound of the 95% confidence interval were 6.4 msec and 12.6 msec for the 10 mg and supratherapeutic 30 mg dose respectively. The Cmax for 30 mg was 1.7-fold higher than the Cmax for the maximum recommended escitalopram dose of 20 mg. Systemic exposure at the 30 mg dose was similar to expected steady state concentrations in 2C19 poor metabolizers following a 20 mg escitalopram dose.(1) In an interaction study, 30 mg of omeprazole, an irreversible inhibitor of CYP2C19 was administered daily for 6 days. On day 5 a single dose of escitalopram 20 mg was also administered; the area-under-curve (AUC) of escitalopram was increased by 50%. Manufacturer prescribing information recommends a maximum citalopram dose of 20mg daily in patients receiving CYP2C19 inhibitors.(1) Inhibitors of CYP2C19 include: abrocitinib, allicin (garlic derivative), berotralstat, cannabidiol (CBD), cenobamate, cimetidine strengths > or = 200 mg, enasidenib, eslicarbazepine, esomeprazole, etravirine, fedratinib, felbamate, fluoxetine, fluvoxamine, givosiran, isoniazid, moclobemide, modafinil, obeticholic acid, omeprazole, piperine, rolapitant, stiripentol, tecovirimat, and tipranavir.(4) |
ESCITALOPRAM OXALATE, LEXAPRO |
| Baloxavir/Polyvalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum, calcium, iron, magnesium, selenium, and zinc may form chelation compounds with baloxavir.(1) CLINICAL EFFECTS: Simultaneous administration of products containing aluminum, calcium, iron, magnesium, selenium, and zinc may result in decreased levels of and clinical effects from baloxavir.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid concurrent administration of baloxavir with cation-containing products.(1) DISCUSSION: A significant decrease in baloxavir exposure was observed when baloxavir was coadministered with calcium, aluminum, magnesium, or iron in monkeys. No studies have been conducted in humans.(1) |
XOFLUZA |
| Trientine/Selected Minerals, Oral SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Mineral supplements may bind to trientine and block its absorption. CLINICAL EFFECTS: The levels and clinical effects of trientine may be decreased. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of trientine states that mineral supplements should not be given with trientine. If concomitant therapy is necessary, take trientine on an empty stomach and separate administration at least one hour apart from any other drug. Monitor clinical status for decreased effectiveness and adjust the trientine dose if necessary. DISCUSSION: Multivitamins with minerals may decrease trientine absorption so ensure patient is aware of the risks. |
CUVRIOR, SYPRINE, TRIENTINE HCL |
| Tacrolimus/Moderate and Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak inhibitors of CYP3A4 may inhibit the metabolism of tacrolimus.(1) CLINICAL EFFECTS: Concurrent use of a CYP3A4 inhibitor may result in elevated levels of and toxicity from tacrolimus, including nephrotoxicity, neurotoxicity, and prolongation of the QTc interval and life-threatening cardiac arrhythmias, including torsades de pointes.(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsade de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsade de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsade de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: The US manufacturer of tacrolimus recommends monitoring tacrolimus whole blood trough concentrations and reducing tacrolimus dose if needed.(1) Consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a study of 26 renal transplant recipients, conjugated estrogens 3.75 mg daily increased the tacrolimus dose-corrected concentration of tacrolimus by 85.6%. Discontinuation of the conjugated estrogens led to a decrease in tacrolimus concentration of 46.6%.(3) A case report describes a 65-year-old kidney transplant recipient who was stable on tacrolimus 9 mg per day with trough levels of 5 to 7.5 ng/mL. Ten days after starting on estradiol gel 0.5 mg per day, her tacrolimus level rose to 18.3 ng/mL and serum creatinine (Scr) rose from 1.1 mg/dL at baseline to 2 mg/dL. Tacrolimus dose was reduced by 60%, and trough levels and Scr normalized after two weeks.(4) A study of 16 healthy volunteers found that elbasvir 50 mg/grazoprevir 200 mg daily increased the area-under-curve (AUC) of tacrolimus by 43%, while the maximum concentration (Cmax) of tacrolimus was decreased by 40%.(5) An analysis of FAERS data from 2004-2017, found a significant assoc ation between transplant rejection and concurrent use of tacrolimus and clotrimazole (reporting odds ration 1.92, 95% CI). A retrospective study of 7 heart transplant patients on concurrent tacrolimus and clotrimazole troche showed a significant correlation between tacrolimus trough concentration and AUC after clotrimazole discontinuation. Tacrolimus clearance and bioavailability after clotrimazole discontinuation was 2.2-fold greater (0.27 vs. 0.59 L/h/kg) and the trough concentration decreased from 6.5 ng/mL at 1 day to 5.3 ng/mL at 2 days after clotrimazole discontinuation.(7) A retrospective study of 26 heart transplant patients found that discontinuation of concurrent clotrimazole with tacrolimus in the CYP3A5 expresser group had a 3.3-fold increase in apparent oral clearance and AUC of tacrolimus (0.27 vs. 0.89 L/h/kg) compared to the CYP3A5 non expresser group with a 2.2-fold mean increase (0.18 vs. 0.39 L/h/kg).(8) A study of 6 adult kidney transplant recipients found that clotrimazole (5-day course) increased the tacrolimus AUC 250% and the blood trough concentrations doubled (27.7 ng/ml versus 27.4 ng/ml). Tacrolimus clearance decreased 60% with coadministration of clotrimazole.(9) A case report describes a 23-year-old kidney transplant recipient who was stable on tacrolimus 5 mg twice daily, mycophenolate mofetil 30 mg daily, prednisone (30 mg daily tapered over time to 5 mg), and clotrimazole troche 10 mg four times daily. Discontinuation of clotrimazole resulted in a decrease in tacrolimus trough levels from 13.7 ng/ml to 5.4 ng/ml over a period of 6 days. Clotrimazole was restarted with tacrolimus 6 mg resulting in an increased tacrolimus level of 19.2 ng/ml.(10) A retrospective study in 95 heart transplant recipients on concurrent clotrimazole and tacrolimus found a median tacrolimus dose increase of 66.7% was required after clotrimazole discontinuation. Tacrolimus trough concentration was found to have decreased 42.5% after clotrimazole discontinuation.(11) A retrospective study in 65 pancreas transplant patients on concurrent tacrolimus, clotrimazole, cyclosporine, and prednisone found that clotrimazole discontinuation at 3 months after transplantation may cause significant tacrolimus trough level reductions.(12) Moderate CYP3A4 inhibitors linked to this monograph include: aprepitant, berotralstat, clofazimine, conivaptan, fluvoxamine, lenacapavir, letermovir, netupitant, nirogacestat, stiripentol, and tofisopam.(6) Weak CYP3A4 inhibitors linked to this monograph include: alprazolam, avacopan, baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, chlorzoxazone, cimetidine, cranberry juice, daclatasvir, daridorexant, delavirdine, diosmin, estrogens, flibanserin, fosaprepitant, fostamatinib, ginkgo biloba, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, linagliptin, lomitapide, lumateperone, lurasidone, peppermint oil, piperine, propiverine, ranitidine, remdesivir, resveratrol, rimegepant, simeprevir, sitaxsentan, skullcap, suvorexant, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan-amoxicillin.(6) |
ASTAGRAF XL, ENVARSUS XR, PROGRAF, TACROLIMUS, TACROLIMUS XL |
| Lemborexant (Less Than or Equal To 5 mg)/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of CYP3A4 may inhibit the metabolism of lemborexant.(1) CLINICAL EFFECTS: Concurrent use of an inhibitor of CYP3A4 may result in increased levels of and effects from lemborexant, including somnolence, fatigue, CNS depressant effects, daytime impairment, headache, and nightmare or abnormal dreams.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The maximum recommended dose of lemborexant with concurrent use of a weak CYP3A4 inhibitors should not exceed 5 mg per dose.(1) DISCUSSION: Lemborexant is a CYP3A4 substrate. In a PKPB model, concurrent use of lemborexant with itraconazole increased area-under-curve (AUC) and concentration maximum (Cmax) by 3.75-fold and 1.5-fold, respectively. Concurrent use of lemborexant with fluconazole increased AUC and Cmax by 4.25-fold and 1.75-fold, respectively.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, belumosudil, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, daridorexant, delavirdine, dihydroberberine, diosmin, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, mavorixafor, olaparib, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, rucaparib, selpercatinib, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(1,2) |
DAYVIGO |
| Ubrogepant/Weak CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Weak inhibitors of CYP3A4 may inhibit the metabolism of ubrogepant.(1) CLINICAL EFFECTS: Concurrent use of ubrogepant with weak CYP3A4 inhibitors may result in an increase in exposure of ubrogepant.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer recommends a dosage adjustment of ubrogepant when used concomitantly with weak CYP3A4 inhibitors. Initial dose of ubrogepant should not exceed 50 mg when used concomitantly with weak inhibitors of CYP3A4. A second dose may be given within 24 hours but should not exceed 50 mg when used concurrently with weak CYP3A4 inhibitors.(1) DISCUSSION: Coadministration of ubrogepant with verapamil, a moderate CYP3A4 inhibitor, resulted in a 3.5-fold and 2.8-fold increase in area-under-curve (AUC) and concentration maximum (Cmax), respectively. No dedicated drug interaction study was conducted to assess concomitant use with weak CYP3A4 inhibitors. The conservative prediction of the maximal potential increase in ubrogepant exposure with weak CYP3A4 inhibitors is not expected to be more than 2-fold.(1) Weak inhibitors of CYP3A4 include: alprazolam, amiodarone, amlodipine, asciminib, azithromycin, Baikal skullcap, berberine, bicalutamide, blueberry, brodalumab, cannabidiol, capivasertib, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clotrimazole, cranberry, cyclosporine, daclatasvir, delavirdine, dihydroberberine, diosmin, elagolix, everolimus, flibanserin, fosaprepitant, fostamatinib, gepotidacin, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lapatinib, larotrectinib, lazertinib, leflunomide, levamlodipine, linagliptin, lomitapide, lurasidone, maribavir, mavorixafor, osilodrostat, palbociclib, pazopanib, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, roxithromycin, simeprevir, sitaxsentan, skullcap, suvorexant, teriflunomide, ticagrelor, tolvaptan, trofinetide, viloxazine, and vonoprazan.(2,3) |
UBRELVY |
| Bosutinib; Neratinib/Selected H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The solubility of bosutinib(1) and neratinib(2) is pH dependent. Changes in gastric pH from H2 antagonists may decrease the absorption of bosutinib and neratinib. CLINICAL EFFECTS: Use of H2 antagonists may result in decreased levels and effectiveness of bosutinib(1) and neratinib.(2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Consider the use of short-acting antacids in patients taking bosutinib(1) and neratinib.(2) If antacids are used, separate the administration times by at least 2 hours for bosutinib(1) and 3 hours for neratinib.(2) If H2 antagonist therapy is required with bosutinib, separate administration of the H2 blocker by at least 2 hours before or 2 hours after bosutinib.(1) If H2 antagonist therapy is required with neratinib, then neratinib must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker.(2) Avoid the use of proton pump inhibitors (PPIs) in patients receiving treatment with bosutinib(1) and neratinib.(2) DISCUSSION: A single dose of bosutinib 400 mg was administered alone or following multiple doses of lansoprazole 60 mg without food. Lansoprazole decreased bosutinib maximum concentration (Cmax) and area-under-curve (AUC) by 46% and 26%, respectively.(1) In a study in 15 healthy subjects, lansoprazole 30 mg daily decreased the Cmax and AUC of a single dose of neratinib (240 mg) by 71% and 65%, respectively.(2) |
BOSULIF, NERLYNX |
| Infigratinib; Selpercatinib/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The solubility of infigratinib and selpercatinib is pH dependent. Antacid-induced changes in gastric pH may decrease the absorption of infigratinib and selpercatinib.(1,2) CLINICAL EFFECTS: Simultaneous administration of antacids may result in decreased levels and effectiveness of infigratinib and selpercatinib.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Avoid the use of antacids, proton pump inhibitors (PPIs), and H2 antagonists, in patients receiving treatment with infigratinib or selpercatinib. If coadministration with antacids cannot be avoided, take infigratinib or selpercatinib at least 2 hours before or 2 hours after the antacid.(1,2) If the antacid is replaced with a H2 antagonist, take infigratinib or selpercatinib 2 hours before or 10 hours after the H2 antagonist.(1,2) If the antacid is replaced with a PPI, take selpercatinib with food.(2) DISCUSSION: Infigratinib is practically insoluble at pH 6.8.(1) Selpercatinib solubility is pH dependent.(2) Antacids may decrease the solubility and absorption of infigratinib and selpercatinib and decrease their effectiveness. |
RETEVMO |
| Zonisamide/Anticholinergics SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Zonisamide can cause decreased sweating and elevated body temperature. Agents with anticholinergic activity can predispose patients to heat-related disorders.(1-2) CLINICAL EFFECTS: Concurrent use of zonisamide with agents with anticholinergic activity may increase the incidence of oligohidrosis and hyperthermia, especially in pediatric or adolescent patients.(1-2) Overheating and dehydration can lead to brain damage and death. PREDISPOSING FACTORS: Pediatric and adolescent patients and patients with dehydration may be more likely to experience heat-related disorders.(1) PATIENT MANAGEMENT: The UK and US manufacturers of zonisamide state that caution should be used in adults when zonisamide is prescribed with other medicinal products that predispose to heat-related disorders, such as agents with anticholinergic activity.(1-2) Pediatric and adolescent patients must not take anticholinergic agents (e.g. clomipramine, hydroxyzine, diphenhydramine, haloperidol, imipramine, and oxybutynin) concurrently with zonisamide.(1) Monitor for signs and symptoms of heat stroke: skin feels very hot with little or no sweating, confusion, muscle cramps, rapid heartbeat, or rapid breathing. Monitor for signs and symptoms of dehydration: dry mouth, urinating less than usual, dark-colored urine, dry skin, feeling tired, dizziness, or irritability. If signs or symptoms of dehydration, oligohidrosis, or elevated body temperature occur, discontinuation of zonisamide should be considered. DISCUSSION: Case reports of decreased sweating and elevated temperature have been reported, especially in pediatric patients. Some cases resulted in heat stroke that required hospital treatment and resulted in death.(1) |
ZONEGRAN, ZONISADE, ZONISAMIDE |
| Chenodiol/Aluminum-Based Antacids; Bile Acid Sequestrants SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum-based antacids, cholestyramine, or colestipol may bind to chenodiol, which may decrease gastrointestinal absorption and impair enterohepatic recirculation of chenodiol.(1,2) CLINICAL EFFECTS: Simultaneous administration of an aluminum-based antacid, cholestyramine, or colestipol may result in decreased absorption and effectiveness of chenodiol.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If concomitant therapy with aluminum-based antacids or colestipol is necessary, administer chenodiol at least 2 hours before or after the antacid or colestipol. If concomitant therapy with cholestyramine is necessary, administer chenodiol at least 1 hour before or 4-6 hours after cholestyramine.(2) DISCUSSION: Aluminum-based antacids have been shown to adsorb bile acids in vitro. Bile acid sequestrants reduce bile acid absorption.(1) |
CHENODAL, CTEXLI |
| Topiramate/Anticholinergics SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Topiramate can cause decreased sweating and elevated body temperature. Agents with anticholinergic activity can predispose patients to heat-related disorders.(1-2) CLINICAL EFFECTS: Concurrent use of topiramate with agents with anticholinergic activity may increase the incidence of oligohidrosis and hyperthermia, especially in pediatric or adolescent patients.(1-2) Overheating and dehydration can lead to brain damage and death. PREDISPOSING FACTORS: Pediatric and adolescent patients and patients with dehydration may be more likely to experience heat-related disorders.(1) PATIENT MANAGEMENT: The manufacturer of topiramate states that caution should be used when topiramate is prescribed with other medicinal products that predispose to heat-related disorders, such as agents with anticholinergic activity (e.g. clomipramine, hydroxyzine, diphenhydramine, haloperidol, imipramine, and oxybutynin) concurrently with zonisamide.(1) Monitor for signs and symptoms of heat stroke: skin feels very hot with little or no sweating, confusion, muscle cramps, rapid heartbeat, or rapid breathing. Monitor for signs and symptoms of dehydration: dry mouth, urinating less than usual, dark-colored urine, dry skin, feeling tired, dizziness, or irritability. If signs or symptoms of dehydration, oligohidrosis, or elevated body temperature occur, discontinuation of zonisamide should be considered. DISCUSSION: Case reports of decreased sweating and elevated temperature have been reported, especially in pediatric patients. Some cases resulted in heat stroke that required hospital treatment.(1) A 64-year old woman developed non-exertional hyperthemia while taking multiple psychiatric medications with topiramate.(2) |
EPRONTIA, PHENTERMINE-TOPIRAMATE ER, QSYMIA, TOPAMAX, TOPIRAMATE, TOPIRAMATE ER, TOPIRAMATE ER SPRINKLE, TROKENDI XR |
| Flecainide/MATE Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of the Multidrug and Toxin Extrusion (MATE) protein transporters in the kidneys may interfere with the renal elimination of flecainide.(1) CLINICAL EFFECTS: Concurrent use of MATE renal transporter inhibitors may result in increased levels of and toxicity from flecainide.(1) PREDISPOSING FACTORS: Risk factors for QT prolongation include: cardiovascular disease (e.g. heart failure, recent myocardial infarction, history of torsades de pointes, congenital long QT syndrome), female sex, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, advanced age, and concurrent use of agents known to cause QT prolongation.(2) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(2) PATIENT MANAGEMENT: Monitor serum flecainide concentrations and observe the patients for signs of toxicity. If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a pharmacokinetic study, concurrent use of cimetidine (1 gram daily) increased flecainide levels by 30% and increased half-life by 10%.(1) MATE inhibitors linked include: abemaciclib, bictegravir, cimetidine, isavuconazole, pyrimethamine, risdiplam, trimethoprim, and tucatinib.(4,5) |
FLECAINIDE ACETATE |
| Oxaliplatin/MATE Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Inhibitors of the Multidrug and Toxin Extrusion (MATE) protein transporters in the kidneys may inhibit the renal transport of oxaliplatin.(1) Oxaliplatin is a MATE substrate.(2,3) CLINICAL EFFECTS: Concurrent use of MATE renal transporter inhibitors may result in increased levels of and toxicity from oxaliplatin, including QT prolongation and neutropenia.(1) PREDISPOSING FACTORS: Risk factors for QT prolongation include: cardiovascular disease (e.g. heart failure, recent myocardial infarction, history of torsades de pointes, congenital long QT syndrome), female sex, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, advanced age, and concurrent use of agents known to cause QT prolongation.(4) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(4) PATIENT MANAGEMENT: Concurrent use of oxaliplatin with MATE renal transporter inhibitors should be approached with caution and monitored closely. If concurrent use is warranted, monitor for toxicities of oxaliplatin and consider dosage reduction based on toxicity dose recommendations.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: Oxaliplatin is a MATE substrate.(2,3) MATE inhibitors include: abemaciclib, bictegravir, cimetidine, isavuconazole, pyrimethamine, risdiplam, trimethoprim, and tucatinib.(6,7) |
OXALIPLATIN |
| Cabotegravir/Polyvalent Cations SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cabotegravir chelates polyvalent cations such as aluminum, calcium, iron, magnesium, selenium, and zinc.(1) CLINICAL EFFECTS: Simultaneous administration of cabotegravir and polyvalent cations may decrease the absorption and clinical effects of cabotegravir.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of cabotegravir states that it should be administered at least 2 hours before or 4 hours after any medications or products containing polyvalent cations such as antacids or mineral supplements.(1) DISCUSSION: Clinical studies have not been conducted. Prescribing information states cabotegravir levels may be decreased when coadministered with antacids containing polyvalent cations (examples include aluminum or magnesium hydroxide, calcium carbonate) suggesting cabotegravir is susceptible to chelation.(1) |
VOCABRIA |
| Clofarabine/OCT2 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Agents that inhibit the organic cation transporter 2 (OCT2) may inhibit the excretion of clofarabine by OCT2 in the kidneys.(1,2) CLINICAL EFFECTS: Concurrent use of OCT2 renal transport inhibitors may result in increased levels of and toxicity from clofarabine, including myelosuppression, serious hemorrhages, enterocolitis, nephrotoxicity, and hepatotoxicity.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Consider the potential benefits against the risks of concurrent use of clofarabine with OCT2 renal transport inhibitors. If concurrent use is appropriate, monitor for toxicities of the clofarabine and consider dosage reduction of clofarabine.(1) DISCUSSION: In an animal study, cimetidine, an OCT2 inhibitor, decreased the clearance of clofarabine in rats by 61%. The clinical implications of this finding are unclear.(1,2) In a study, givinostat increased the levels of creatinine (OCT2 substrate) by 4.76 umol/L from baseline.(3) In a study, trilaciclib increased the area-under-curve (AUC) and maximum concentration (Cmax) of metformin (an OCT2, MATE1, and MATE-2K substrate) by approximately 65% and 81%, respectively. Renal clearance of metformin was decreased by 37%. Trilaciclib did not cause significant changes in the pharmacokinetics of topotecan (a MATE1 and MATE-2K substrate).(4) OCT2 inhibitors linked to this monograph include: abemaciclib, arimoclomol, bictegravir, cimetidine, dolutegravir, givinostat, isavuconazole, ranolazine, trilaciclib, trimethoprim, tucatinib, and vimseltinib.(5) |
CLOFARABINE |
| Procainamide/OCT2 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Agents that inhibit the organic cation transporter 2 (OCT2) may inhibit the excretion of procainamide by OCT2 in the kidneys.(1,2) CLINICAL EFFECTS: Concurrent use of OCT2 renal transport inhibitors may result in increased levels of and toxicities of procainamide,(1,2) including potentially life-threatening cardiac arrhythmias, like torsades de pointes (TdP).(3) PREDISPOSING FACTORS: Risk factors for QT prolongation include: cardiovascular disease (e.g. heart failure, recent myocardial infarction, history of torsades de pointes, congenital long QT syndrome), female sex, hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, advanced age, and concurrent use of agents known to cause QT prolongation.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: Consider the potential benefits against the risks of concurrent use of procainamide with OCT2 renal transport inhibitors. If concurrent use is appropriate, monitor for toxicities of procainamide and consider dosage reduction of procainamide.(1) If concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring ECG at baseline and at regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: In a study, givinostat increased the levels of creatinine (OCT2 substrate) by 4.76 umol/L from baseline.(1) In a study, trilaciclib increased the area-under-curve (AUC) and maximum concentration (Cmax) of metformin (an OCT2, MATE1, and MATE-2K substrate) by approximately 65% and 81%, respectively. Renal clearance of metformin was decreased by 37%. Trilaciclib did not cause significant changes in the pharmacokinetics of topotecan (a MATE1 and MATE-2K substrate).(2) OCT2 inhibitors linked to this monograph include: abemaciclib, arimoclomol, bictegravir, cimetidine, dolutegravir, givinostat, isavuconazole, trilaciclib, tucatinib, and vimseltinib.(4) |
PROCAINAMIDE HCL |
| Sotorasib/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of sotorasib is pH dependent. Higher gastric pH leads to lower solubility which may reduce sotorasib absorption.(1) CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of sotorasib, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of sotorasib with proton pump inhibitors, H2 antagonists, and antacids should be avoided. If coadministration with an acid-reducing agent is unavoidable, take sotorasib 4 hours before or 10 hours after a locally acting antacid.(1) DISCUSSION: The solubility of sotorasib in the aqueous media decreases over the range pH 1.2 to 6.8 from 1.3 mg/mL to 0.03 mg/mL. In an interaction study, coadministration of repeat doses of omeprazole with a single dose of sotorasib decreased sotorasib maximum concentration (Cmax) by 65% and area-under-curve (AUC) by 57% under fed conditions, and decreased sotorasib Cmax by 57% and AUC by 42% under fasted conditions. Coadministration of a single dose of famotidine given 10 hours prior to and 2 hours after a single dose of sotorasib under fed conditions decreased sotorasib Cmax by 35% and AUC by 38%.(1) |
LUMAKRAS |
| Pexidartinib/Selected H2 Antagonists SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The solubility of pexidartinib is pH dependent. Changes in gastric pH from H2 antagonists may decrease the absorption of pexidartinib.(1) CLINICAL EFFECTS: Use of H2 antagonists may result in decreased levels and effectiveness of pexidartinib.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Consider the use of short-acting antacids in patients taking pexidartinib. If antacids are used, separate the administration times by at least 2 hours. If H2 antagonist therapy is required, the pexidartinib must be given 10 hours after the H2 blocker and at least 2 hours before the next dose of the H2 blocker. Avoid the use of proton pump inhibitors (PPIs).(1) DISCUSSION: Coadministration of esomeprazole decreased pexidartinib maximum concentration (Cmax) and area-under-curve (AUC) by 55% and 50%, respectively.(1) |
TURALIO |
| Sirolimus Protein-Bound/Slt Moderate and Weak CYP3A4 Inhibit SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate and weak CYP3A4 inhibitors may inhibit the metabolism of sirolimus by CYP3A4.(1) CLINICAL EFFECTS: Concurrent use of moderate or weak CYP3A4 inhibitors may result in elevated levels of and side effects from sirolimus.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US manufacturer of sirolimus protein-bound injection (Fyarro) states a dose reduction to 56 mg/m2 is recommended when used concurrently with moderate or weak CYP3A4 inhibitors. Concurrent use with strong CYP3A4 inhibitors should be avoided.(1) DISCUSSION: In an open, randomized, cross-over trial in 18 healthy subjects, concurrent single doses of diltiazem (120 mg) and sirolimus (10 mg) increased sirolimus area-under-curve (AUC) and maximum concentration (Cmax) by 60% and by 43%, respectively. Sirolimus apparent oral clearance and volume of distribution decreased by 38% and 45%, respectively. There were no effects on diltiazem pharmacokinetics or pharmacodynamics.(2) In a study in 26 healthy subjects, concurrent sirolimus (2 mg daily) with verapamil (180 mg twice daily) increased sirolimus AUC and Cmax by 2.2-fold and 2.3-fold, respectively. The AUC and Cmax of the active S-enantiomer of verapamil each increased by 1.5-fold. Verapamil time to Cmax (Tmax) was increased by 1.2 hours.(2) Moderate and weak CYP3A4 inhibitors linked to this monograph include: alprazolam, amlodipine, aprepitant, avacopan, azithromycin, berberine, berotralstat, bicalutamide, blueberry, brodalumab, chlorzoxazone, cilostazol, cimetidine, ciprofloxacin, clofazimine, conivaptan, daclatasvir, daridorexant, delavirdine, diosmin, entrectinib, erythromycin, estrogen, flibanserin, fluvoxamine, fosaprepitant, fosnetupitant, fostamatinib, ginkgo, givinostat, glecaprevir/pibrentasvir, goldenseal, grazoprevir, isoniazid, istradefylline, ivacaftor, lacidipine, lazertinib, lenacapavir, levamlodipine, linagliptin, lomitapide, lumateperone, lurasidone, mavorixafor, netupitant, omeprazole, osilodrostat, peppermint oil, piperine, propiverine, propofol, ranitidine, ranolazine, remdesivir, resveratrol, rimegepant, roxithromycin, scutellarin, simeprevir, sitaxsentan, stiripentol, suvorexant, ticagrelor, tofisopam, tolvaptan, trofinetide, and vonoprazan.(3,4) |
FYARRO |
| Levoketoconazole/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of levoketoconazole is pH dependent. Higher gastric pH leads to lower solubility. Antacids increase gastric pH and may decrease the absorption of levoketoconazole.(1) CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of levoketoconazole, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of levoketoconazole with proton pump inhibitors and H2 antagonists should be avoided. If coadministration with an acid-reducing agent is unavoidable, take the antacid 2 hours before levoketoconazole.(1) DISCUSSION: Levoketoconazole is very slightly soluble in water but soluble below pH 2. Antacids raise gastric pH and may impair dissolution and absorption of levoketoconazole.(1) |
RECORLEV |
| Zolmitriptan (Less Than or Equal To 2.5 mg)/Cimetidine SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Cimetidine inhibits the CYP1A2 mediated metabolism of zolmitriptan and its active N-desmethyl metabolite.(1,2) CLINICAL EFFECTS: Increased concentrations of zolmitriptan and its active N-desmethyl metabolite may increase the risk for adverse effects such as paresthesia, dizziness, or sensation of heaviness or tightness in the neck/throat/jaw, or chest.(1) PREDISPOSING FACTORS: Due to the extended half-life associated with concurrent cimetidine use, multiple doses of zolmitriptan within a 24-hour period may lead to accumulation, increasing the risk for adverse effects.(1,2) PATIENT MANAGEMENT: The manufacturer of zolmitriptan recommends the maximum single dose be reduced to 2.5 mg, not to exceed 5 mg in any 24-hour period.(1) When possible, consider use of an alternative acid reducing agent. DISCUSSION: Zolmitriptan is converted to several metabolites, but only the N-desmethyl metabolite is active. Although plasma concentrations are about 2/3 of the parent drug, the N-desmethyl metabolite is 2 to 6 times more potent at 5-HT1B/1D receptors than zolmitriptan and may contribute substantially to its pharmacologic effect.(1) Zolmitriptan added to therapeutic doses of cimetidine 400 mg three times a day increased the area-under-curve(AUC) for zolmitriptan and its active N-desmethyl metabolite of approximately 1.5 fold and 2 fold respectively.(1,2) An open 2 period crossover study in 16 volunteer subjects evaluated the pharmacokinetics of zolmitriptan and the N-desmethyl metabolite with or without cimetidine 400mg every 8 hours for 2 days. After cimetidine treatment, the AUC of zolmitriptan and the N-desmethyl metabolite increased 1.48 and 2.05 fold respectively. The half-life of zolmitriptan increased from 4.99 to 7.19 hours, while the active metabolite half-life increased from 3.81 to 8.00 hours after treatment with cimetidine.(2) |
ZOLMITRIPTAN, ZOLMITRIPTAN ODT, ZOMIG |
| Sparsentan/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of sparsentan is pH dependent. Higher gastric pH leads to lower solubility. Antacids increase gastric pH and may decrease the absorption of sparsentan.(1) CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of sparsentan, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If coadministration with an acid-reducing agent is unavoidable, take an antacid 2 hours before or 2 hours after sparsentan. Coadministration of sparsentan with proton pump inhibitors and H2 antagonists should be avoided.(1) DISCUSSION: Sparsentan is practically insoluble in water but has intrinsic solubility of 1.48 mg/mL and 0.055 mg/mL below pH 1.2 and 6.8, respectively. Antacids raise gastric pH and may impair dissolution and absorption of sparsentan.(1) |
FILSPARI |
| Amphetamines/Antacids; Urinary Alkalinizers SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Antacids and urinary alkalinizers increase the absorption of amphetamines. CLINICAL EFFECTS: Concurrent use of amphetamines and antacids or urinary alkalinizers may result in increased amphetamine levels and side effects. PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The US and Canadian manufacturers state that coadministration of alkalinizing agents with amphetamines should be avoided.(1-3) The Canadian manufacturer states that concurrent use of proton pump inhibitors and amphetamines should be avoided.(3) The US manufacturer states that patients receiving concurrent therapy should be monitored for changes in clinical effects.(1) Monitor patients receiving concurrent therapy for changes in amphetamine effectiveness and side effects. If concurrent use cannot be avoided, separate the administration times of amphetamines and antacids. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: Concurrent use of alkalinizing agents with amphetamines increase the absorption of amphetamines. Co-administration of these should be avoided because of the potential of increased actions of the amphetamines.(1,2) |
ADDERALL, ADDERALL XR, ADZENYS XR-ODT, AMPHETAMINE SULFATE, DESOXYN, DEXEDRINE, DEXTROAMPHETAMINE SULFATE, DEXTROAMPHETAMINE SULFATE ER, DEXTROAMPHETAMINE-AMPHET ER, DEXTROAMPHETAMINE-AMPHETAMINE, DYANAVEL XR, EVEKEO, METHAMPHETAMINE HCL, MYDAYIS, PROCENTRA, ZENZEDI |
| Nirogacestat/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of nirogacestat is pH dependent. Higher gastric pH leads to lower solubility which may reduce nirogacestat absorption.(1) CLINICAL EFFECTS: Coadministration of antacids may reduce the bioavailability of nirogacestat, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Coadministration of nirogacestat with proton pump inhibitors, H2 antagonists, and antacids should be avoided. If coadministration with an acid-reducing agent is unavoidable, take nirogacestat 2 hours before or 2 hours after a locally acting antacid.(1) DISCUSSION: The solubility of nirogacestat is poor at a pH >= 6.(1) Concomitant use of proton pump inhibitors, H2 antagonists, or antacids are expected to reduce concentrations of nirogacestat.(1) |
OGSIVEO |
| Vadadustat/Polyvalent Cations and Phosphate Binders SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Vadadustat may form a chelate with iron supplements, phosphate binders, and other medicinal products whose primary component consists of polyvalent cations such as aluminum, calcium, magnesium, selenium, and zinc.(1) CLINICAL EFFECTS: Simultaneous administration of vadadustat and polyvalent cations and phosphate binders decreases the exposure and effectiveness of vadadustat.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of vadadustat states that it should be administered at least 1 hour before or 2 hours after any medications or products whose primary component consists of iron, phosphate binders and polyvalent cations.(1) DISCUSSION: Two studies evaluating the pharmacokinetics, safety, and tolerability of a single oral dose of vadadustat coadministered with a phosphate binder or iron supplement were conducted in healthy adult participants. Vadadustat exposure was reduced by coadministration with sevelamer carbonate, calcium acetate, ferric citrate, and ferrous sulfate. Geometric least squares mean ratios for area under the concentration-time curve (AUC) were reduced 37% to 55% by phosphate binders and 46% by ferrous sulfate. However, when vadadustat was administered 1 hour before phosphate binders, 90% confidence intervals for vadadustat exposure were within the no-effect boundaries of +50% to -33%, indicating that drug-drug interactions can be reduced by administering vadadustat 1 hour before phosphate binders.(2) |
VAFSEO |
| Cefpodoxime/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Absorption of oral cefpodoxime may be reduced in patients receiving concomitant treatment with acid reducing agents.(1-3) CLINICAL EFFECTS: Antibiotic efficacy against organisms with a high minimum inhibitory concentration (MIC) to cefpodoxime could be decreased. PREDISPOSING FACTORS: Taking cefpodoxime on an empty stomach magnifies this effect. PATIENT MANAGEMENT: Separate the administration of cefpodoxime by at least 1-2 hours after administration of antacids. Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. Since concurrent use of H2 antagonists and proton pump inhibitors (PPIs) in patients taking cefpodoxime should be avoided, these would not be alternatives to antacids in these patients. DISCUSSION: In a study of ten subjects, administration of cefpodoxime after single dose famotidine 40 mg decreased both maximum concentration (Cmax) and area-under-curve (AUC) by approximately 40% compared with administration of cefpodoxime on an empty stomach.(2) In a study of 17 subjects, administration of cefpodoxime after single dose ranitidine 150 mg decreased Cmax and AUC by approximately 40% compared with administration of cefpodoxime on an empty stomach.(3) |
CEFPODOXIME PROXETIL |
| Sotalol/Aluminium And Magnesium Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Aluminum- and magnesium-containing antacids may reduce the absorption of sotalol.(1) CLINICAL EFFECTS: Simultaneous administration of sotalol with antacids containing aluminum or magnesium may result in decreased levels and effectiveness of sotalol.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: If coadministration with an aluminum- or magnesium-containing antacid agent is unavoidable, take the antacid 2 hours before or 2 hours after sotalol.(1) DISCUSSION: In a study with 6 healthy volunteers, administration of oral sotalol simultaneously with antacids reduced the maximum concentration (Cmax) and area under the curve (AUC) of sotalol by 26% and 20%, respectively, compared to sotalol alone. There was a 25% reduction in the bradycardic effect at rest. Administration of the antacid two hours after oral sotalol had no effect on the pharmacokinetics or pharmacodynamics of sotalol.(1,2) |
BETAPACE, BETAPACE AF, SOTALOL, SOTALOL AF, SOTYLIZE |
| Mavorixafor/Moderate CYP3A4 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Moderate CYP3A4 inhibitors may inhibit the metabolism of mavorixafor.(1) Mavorixafor is also a substrate of P-glycoprotein (P-gp). P-gp inhibitors may increase mavorixafor exposure.(1) Many CYP3A4 inhibitors also inhibit P-glycoprotein (P-gp), including cimetidine, diltiazem, fluvoxamine, isavuconazonium, schisandra, and verapamil.(2) CLINICAL EFFECTS: Concurrent use of moderate CYP3A4 inhibitors may increase the levels and effects of mavorixafor, including thrombocytopenia and QTc prolongation, which may result in potentially life-threatening cardiac arrhythmias like torsades de pointes (TdP).(1) PREDISPOSING FACTORS: The risk of QT prolongation or torsades de pointes may be increased in patients with cardiovascular disease (e.g. heart failure, myocardial infarction, history of torsades de pointes, congenital long QT syndrome), hypokalemia, hypomagnesemia, hypocalcemia, bradycardia, female gender, or advanced age.(3) Concurrent use of more than one drug known to cause QT prolongation or higher systemic concentrations of either QT prolonging drug are additional risk factors for torsades de pointes. Factors which may increase systemic drug concentrations include rapid infusion of an intravenous dose or impaired metabolism or elimination of the drug (e.g. coadministration with an agent which inhibits its metabolism or elimination, genetic impairment in drug metabolism or elimination, and/or renal/hepatic dysfunction).(3) PATIENT MANAGEMENT: When used concomitantly with moderate CYP3A4 inhibitors, monitor more frequently for mavorixafor adverse effects and reduce the dose in 100 mg increments, if necessary, but not to a dose less than 200 mg.(1) When concurrent therapy is warranted, consider obtaining serum calcium, magnesium, and potassium levels and monitoring EKG at baseline and regular intervals. Correct any electrolyte abnormalities. Instruct patients to report any irregular heartbeat, dizziness, or fainting. DISCUSSION: There are no clinical studies for the combination of mavorixafor and moderate CYP3A4 inhibitors. In a study with healthy subjects, itraconazole 200 mg daily (a strong CYP3A4 and P-gp inhibitor) increased the exposure to single-dose mavorixafor 200 mg similar to that from single-dose mavorixafor 400 mg alone. This suggests that itraconazole increased mavorixafor exposure by about 2-fold.(1) A study in healthy volunteers found that ritonavir 100 mg twice daily (a strong CYP3A4 inhibitor and P-gp inhibitor) increased the area-under-curve (AUC) and maximum concentration (Cmax) of single-dose mavorixafor 200 mg by 60% and 39%, respectively.(4) Moderate inhibitors of CYP3A4 include: amprenavir, aprepitant, atazanavir, avacopan, berotralstat, cimetidine, clofazimine, conivaptan, darunavir, diltiazem, duvelisib, fedratinib, fluvoxamine, fosamprenavir, fosnetupitant, imatinib, isavuconazonium, lenacapavir, letermovir, netupitant, schisandra, stiripentol, tofisopam, treosulfan, verapamil and voxelotor.(2,5) |
XOLREMDI |
| Pindolol/OCT2 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Agents that inhibit the organic cation transporter 2 (OCT2) may inhibit the excretion of pindolol by OCT2 in the kidneys.(1,2) CLINICAL EFFECTS: Concurrent use of OCT2 renal transport inhibitors may result in increased levels of and toxicity from pindolol.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Consider the potential benefits against the risks of concurrent use of pindolol with OCT2 renal transport inhibitors. If concurrent use is appropriate, monitor for toxicities of pindolol and consider dosage reduction of pindolol.(1,2) DISCUSSION: In a study, givinostat increased the levels of creatinine (OCT2 substrate) by 4.76 umol/L from baseline.(1) In a study, trilaciclib increased the area-under-curve (AUC) and maximum concentration (Cmax) of metformin (an OCT2, MATE1, and MATE-2K substrate) by approximately 65% and 81%, respectively. Renal clearance of metformin was decreased by 37%. Trilaciclib did not cause significant changes in the pharmacokinetics of topotecan (a MATE1 and MATE-2K substrate).(2) OCT2 inhibitors linked to this monograph include: arimoclomol, cimetidine, dolutegravir, givinostat, and vimseltinib.(3) |
PINDOLOL |
| Defactinib/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of defactinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce defactinib absorption.(1) CLINICAL EFFECTS: Coadministration with antacids may reduce the bioavailability of defactinib, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of defactinib states that patients requiring acid-lowering therapy should separate defactinib from antacid administration by 2 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: The impact of antacids on the pharmacokinetics of defactinib has not been investigated in clinical studies. In an interaction study, defactinib area-under-the-curve (AUC) decreased by 79% and maximum concentration (Cmax) decreased by 85% following concomitant use of multiple doses of omeprazole 40 mg daily. The AUC and Cmax of N-desmethyl amide (M4), a major active metabolite of defactinib, decreased by 83% and 88%, respectively.(1) |
AVMAPKI-FAKZYNJA, FAKZYNJA |
| Taletrectinib/Antacids SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: The aqueous solubility of taletrectinib is pH dependent. Higher gastric pH leads to lower solubility which may reduce taletrectinib absorption.(1) CLINICAL EFFECTS: Coadministration with antacids may reduce the bioavailability of taletrectinib, leading to decreased systemic levels and effectiveness.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of taletrectinib states that patients requiring acid-lowering therapy should separate taletrectinib from antacid administration by 2 hours.(1) Some vitamin preparations may contain sufficient quantities of calcium and/or magnesium salts with antacid properties to interact as well. DISCUSSION: The impact of antacids on the pharmacokinetics of taletrectinib has not been investigated in clinical studies. In an interaction study, taletrectinib area-under-the-curve (AUC) decreased by 40% and maximum concentration (Cmax) decreased by 65% following concomitant use of omeprazole 40 mg daily.(1) |
IBTROZI |
The following contraindication information is available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide):
Drug contraindication overview.
No enhanced Contraindications information available for this drug.
No enhanced Contraindications information available for this drug.
There are 1 contraindications.
Absolute contraindication.
| Contraindication List |
|---|
| Gastrointestinal obstruction |
There are 8 severe contraindications.
Adequate patient monitoring is recommended for safer drug use.
| Severe List |
|---|
| Chronic kidney disease stage 4 (severe) GFR 15-29 ml/min |
| Chronic kidney disease stage 5 (failure) GFr<15 ml/min |
| Diarrhea |
| Fecal impaction |
| Gastric cancer |
| Gastrointestinal obstruction |
| Hypernatremia |
| Kidney disease with reduction in glomerular filtration rate (GFr) |
There are 6 moderate contraindications.
Clinically significant contraindication, where the condition can be managed or treated before the drug may be given safely.
| Moderate List |
|---|
| Chronic diarrhea |
| Constipation |
| Hemorrhoids |
| Hypophosphatemia |
| Kidney disease with likely reduction in glomerular filtration rate (GFr) |
| Kidney disease with reduction in glomerular filtration rate (GFr) |
The following adverse reaction information is available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide):
Adverse reaction overview.
No enhanced Common Adverse Effects information available for this drug.
No enhanced Common Adverse Effects information available for this drug.
There are 17 severe adverse reactions.
| More Frequent | Less Frequent |
|---|---|
| None. | None. |
| Rare/Very Rare |
|---|
|
Agranulocytosis Atrioventricular block Bradycardia Erythema multiforme Exfoliative dermatitis Fecal impaction Fever Hypercalcemia Hypermagnesemia Hypersensitivity drug reaction Hypophosphatemia Interstitial nephritis Leukopenia Pancreatitis Stevens-johnson syndrome Tachycardia Thrombocytopenic disorder |
There are 24 less severe adverse reactions.
| More Frequent | Less Frequent |
|---|---|
|
Abdominal pain with cramps Constipation Diarrhea Dysgeusia Headache disorder Nausea Vomiting |
Abdominal pain with cramps Diarrhea Dizziness Drowsy Nausea Skin rash Vomiting |
| Rare/Very Rare |
|---|
|
Abnormal sexual function Acute cognitive impairment Alopecia Anticholinergic toxicity Arthralgia Erectile dysfunction Gynecomastia Mastalgia Myalgia Urinary retention |
The following precautions are available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide):
No enhanced Pediatric Use information available for this drug.
Contraindicated
Severe Precaution
Management or Monitoring Precaution
Contraindicated
| None |
Severe Precaution
| None |
Management or Monitoring Precaution
| None |
Reproduction studies in rats, rabbits, and mice at doses up to 40 times the normal human dose of cimetidine have revealed no evidence of impaired fertility or harm to the fetus. However, there are no adequate and controlled studies to date using cimetidine in pregnant women, and the drug should be used during pregnancy only when clearly needed.
Since cimetidine is distributed into milk, nursing should generally not be undertaken during therapy with the drug. Women who are pregnant or nursing should seek the advice of a health professional before using cimetidine for self-medication.
No enhanced Geriatric Use information available for this drug.
The following prioritized warning is available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide):
No warning message for this drug.
No warning message for this drug.
The following icd codes are available for HEARTBURN RELIEF (magnesium carbonate/aluminum hydroxide)'s list of indications:
| Dyspepsia | |
| K30 | Functional dyspepsia |
| Heartburn | |
| R12 | Heartburn |
Formulary Reference Tool