Driminate

Drug overview for DRIMINATE (dimenhydrinate):

Generic name: DIMENHYDRINATE (DYE-men-HYE-dri-nate)
Drug class: Antiemetic
Therapeutic class: Gastrointestinal Therapy Agents

Dimenhydrinate, an ethanolamine-derivative antihistamine containing a diphenhydramine moiety, is an antiemetic.

No enhanced Uses information available for this drug.

DRUG IMAGES

DRIMINATE 50 MG TABLET

The following indications for DRIMINATE (dimenhydrinate) have been approved by the FDA:

Indications:
Motion sickness
Nausea and vomiting
Nausea
Prevention of motion sickness
Prevention of nausea and vomiting
Vertigo
Vomiting

Professional Synonyms:
Emesis
Nausea and vomiting prophylaxis
Prevention of riders' vertigo
Queasy
Riders' vertigo
Vomit

The following dosing information is available for DRIMINATE (dimenhydrinate):

Dosing
Administration
DRIMINATE
DIMENHYDRINATE

For the prevention of motion sickness, dimenhydrinate should be taken orally 30 minutes before exposure to motion. For the prevention and treatment of nausea, vomiting, and/or vertigo associated with motion sickness, the usual oral dosage of dimenhydrinate for self-medication in adults and children 12 years of age or older is 50-100 mg every 4-6 hours, not to exceed 400 mg in 24 hours, or as directed by a clinician. The same dosage can be given parenterally in adults to treat motion sickness.

Children 6 to younger than 12 years of age may receive 25-50 mg orally every 6-8 hours, not to exceed 150 mg in 24 hours, or as directed by a clinician. Children 2 to younger than 6 years of age may receive 12.5-25 mg orally every 6-8 hours, not to exceed 75 mg in 24 hours, or as directed by a clinician.

Alternatively, children may be given 1.25 mg/kg or 37.5 mg/m2, orally or IM 4 times daily, up to a maximum of 300 mg daily.

Children younger than 2 years of age should receive oral dimenhydrinate only under the direction of a clinician. IV dosage has not been established for children.

For symptomatic relief of Meniere's disease, 25-50 mg of dimenhydrinate has been given orally 3 times daily for maintenance, or 50 mg has been given IM for acute attacks.

Dimenhydrinate may be administered orally or by IM or IV injection. For IV injection, each 50 mg of dimenhydrinate must be diluted with 10 mL of 0.9% sodium chloride injection and administered slowly over a period of 2 minutes.

Dosing information for DRIMINATE
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
DRIMINATE 50 MG TABLET	Maintenance	Adults take 1 tablet (50 mg) by oral route every 6 hours as needed

Generic dosing information for DIMENHYDRINATE
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
DIMENHYDRINATE 50 MG TABLET	Maintenance	Adults take 1 tablet (50 mg) by oral route every 6 hours as needed

The following drug interaction information is available for DRIMINATE (dimenhydrinate):

Contraindicated
Severe
Moderate

There are 0 contraindications.

There are 5 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
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
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
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
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
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

There are 6 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
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, cimetidine, clobazam, 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
Eliglustat/Weak CYP2D6 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Weak inhibitors of CYP2D6 may inhibit the metabolism of eliglustat. If the patient is also taking an inhibitor of CYP3A4, eliglustat metabolism can be further inhibited.(1) CLINICAL EFFECTS: Concurrent use of an agent that is a weak inhibitor of CYP2D6 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 CYP3A4 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 dosage of eliglustat with weak inhibitors of CYP2D6 in poor CYP2D6 metabolizers should be limited to 84 mg daily.(1) The dosage of eliglustat with weak inhibitors of CYP2D6 in extensive CYP2D6 metabolizers 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: Paroxetine (30 mg daily), a strong inhibitor of CYP2D6, increased eliglustat (84 mg BID) maximum concentration (Cmax) and area-under-curve (AUC) by 7-fold and 8.4-fold, respectively, in extensive metabolizers. Physiologically-based pharmacokinetic (PKPB) models suggested paroxetine would increase eliglustat Cmax and AUC by 2.1-fold and 2.3-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 terbinafine, a moderate inhibitor of CYP2D6, would increase eliglustat Cmax and AUC by 3.8-fold and 4.5-fold, respectively, in extensive metabolizers and by 1.6-fold and 1.6-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) A single dose of rolapitant increased dextromethorphan, a CYP2D6 substrate, about 3-fold on days 8 and day 22 following administration. Dextromethorphan levels remained elevated by 2.3-fold on day 28 after single dose rolapitant. The inhibitory effects of rolapitant on CYP2D6 are expected to persist beyond 28 days.(5) Weak inhibitors of CYP2D6 include: alogliptin, artesunate, celecoxib, clobazam, desvenlafaxine, dimenhydrinate, diphenhydramine, dronabinol, dupilumab, echinacea, enasidenib, felodipine, gefitinib, hydralazine, hydroxychloroquine, lorcaserin, methadone, panobinostat, propafenone, sertraline, vemurafenib, and venlafaxine.(3,4)	CERDELGA
Metoprolol/Selected CYP2D6 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: CYP2D6 inhibitors may inhibit the metabolism of metoprolol.(1,2) CLINICAL EFFECTS: Concurrent use of CYP2D6 inhibitors may result in elevated levels of and toxicity from metoprolol.(1,2) PREDISPOSING FACTORS: The interaction may be more severe in patients who are ultrarapid metabolizers of CYP2D6,(1,2) elderly,(3) and on higher doses of beta-blockers.(3) PATIENT MANAGEMENT: Monitor patients receiving concurrent therapy with metoprolol and inhibitors of CYP2D6. The dosage of metoprolol may need to be adjusted.(1,2) The effects of rolapitant, a moderate CYP2D6 inhibitor, on CYP2D6 are expected to last at least 28 days after administration.(4) DISCUSSION: In a case report, a patient maintained on metoprolol developed bradycardia following the addition of bupropion.(5) In a study in 20 healthy females, diphenhydramine increased the AUC of metoprolol by 21%. Heart rate reduction increased 29%.(6) In a randomized study in 16 healthy subjects, diphenhydramine decreased metoprolol oral and nonrenal clearance by 2-fold in extensive 2D6 metabolizers. In extensive 2D6 metabolizers, metoprolol-induced effects on heart rate, systolic blood pressure, and aortic blood flow peak velocity were all increased. There were no effects of diphenhydramine in poor metabolizers.(7) Fluoxetine has been shown to inhibit metoprolol metabolism in vitro.(8) There is a case report of severe bradycardia following the addition of fluoxetine to metoprolol.(9) In a 3-way, randomized, cross-over study in healthy subjects, paroxetine (20 mg daily) increased the area-under-curve (AUC) of both S- and R-metoprolol by 3-fold, and 4-fold, respectively, regardless of whether the formulation of metoprolol was immediate release or extended release. Concurrent paroxetine also significantly decreased heart rate and blood pressure when compared to metoprolol alone.(10) In an open-label, randomized, cross-over study in 10 healthy subjects, paroxetine increased the AUC of S-metoprolol and R-metoprolol from an immediate release formulation (50 mg)by 4-fold and 5-fold, respectively. Paroxetine increased the AUC of S-metoprolol and R-metoprolol from an extended release formulation (100 mg) by 3-fold and 4-fold, respectively.(11) In a study in patients with acute myocardial infarction and depression, paroxetine (20 mg daily) increased the AUC of metoprolol 3-fold. Mean heart rate was significantly lower following the addition of paroxetine to metoprolol. Two patients experienced bradycardia and severe orthostatic hypotension.(12) In an open trial in 8 healthy males, paroxetine (20 mg daily) increased the AUC of S-metoprolol and R-metoprolol by 4-fold and 7-fold, respectively.(13) There are case reports of complete atrioventricular block(14) and bradycardia(15) with concurrent metoprolol and paroxetine. A systematic review and meta-analysis of CYP2D6 interactions between metoprolol and either paroxetine or fluoxetine reviewed 9 articles including 4 primary and 2 observational studies as well as 3 case reports. Experimental studies noted paroxetine increased the AUC of metoprolol 3-fold to 5-fold and significantly decreased blood pressure and heart rate. Paroxetine and fluoxetine have shown equipotent inhibitor capacity on CYP2D6. The metabolite, norfluoxetine, is also an inhibitor of CYP2D6.(16) A retrospective cohort study evaluated morbidity in patients on a beta-blocker primarily metabolized by CYP2D6 (e.g., nebivolol, metoprolol, carvedilol, propranolol, labetalol) and started on a strong or moderate CYP2D6-inhibiting antidepressant (e.g., fluoxetine, paroxetine, bupropion, duloxetine). Use of such an antidepressant with a beta-blocker was associated with an increased risk of hospitalization or ED visit due to an adverse hemodynamic event (HR 1.53, 95% CI 1.03-2.81, p=0.04).(3) CYP2D6 inhibitors include: abiraterone, bupropion, celecoxib, cinacalcet, citalopram, dacomitinib, dimenhydrinate, diphenhydramine, duloxetine, escitalopram, fedratinib, fluoxetine, hydroxychloroquine, imatinib, lorcaserin, osilodrostat, paroxetine, ranitidine, ranolazine, rolapitant, and sertraline. 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.	KAPSPARGO SPRINKLE, LOPRESSOR, METOPROLOL SUCCINATE, METOPROLOL TARTRATE, METOPROLOL-HYDROCHLOROTHIAZIDE, TOPROL XL
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
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
Propranolol/Selected CYP2D6 Inhibitors SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: CYP2D6 inhibitors may inhibit the metabolism of propranolol.(1) CLINICAL EFFECTS: Concurrent use of CYP2D6 inhibitors may result in elevated levels of and toxicity from propranolol, including hypotension and bradycardia.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Monitor patients receiving concurrent therapy with propranolol and CYP2D6 inhibitors. The dosage of propranolol may need to be adjusted.(1) DISCUSSION: In a pharmacokinetic study in 16 healthy volunteers, concurrent use of quinidine 200 mg (a CYP2D6 inhibitor) increased the area-under-curve (AUC) of propranolol by 2.29-fold.(2) In a pharmacokinetic study in 6 healthy subjects, concurrent use of quinidine increased propranolol AUC 2-fold.(3) A retrospective review of concurrent use of propranolol and antidepressants evaluated the risk of hospitalization or emergency room visit within 30 days of concurrent prescription. In patients receiving antidepressants with moderate to strong CYP2D6 inhibitory effects, patient were an increased risk compared to patients receiving no antidepressants (Hazard Ratio (HR) = 1.53; 95% CI 1.03-2.81 vs. HR = 1.24; 95% CI 0.82-1.88).(4) Case reports of bradycardia and cardiac adverse effects have been reported with concurrent use of propranolol and the antidepressants fluoxetine and paroxetine (strong CYP2D6 inhibitors).(5) Strong CYP2D6 inhibitors include: bupropion, dacomitinib, fluoxetine, mavorixafor, and paroxetine. Moderate CYP2D6 inhibitors include: abiraterone, asunaprevir, berotralstat, capivasertib, cinacalcet, duloxetine, eliglustat, escitalopram, lorcaserin, mirabegron, moclobemide, quinine, ranolazine, and rolapitant. Weak CYP2D6 inhibitors include: celecoxib, desvenlafaxine, diphenhydramine, dimenhydrinate, dronabinol, fedratinib, hydroxychloroquine, imatinib, osilodrostat, ranitidine, and sertraline.(6)	HEMANGEOL, INDERAL LA, INDERAL XL, INNOPRAN XL, PROPRANOLOL HCL, PROPRANOLOL HCL ER, PROPRANOLOL-HYDROCHLOROTHIAZID

The following contraindication information is available for DRIMINATE (dimenhydrinate):

Overview
Contraindicated
Severe
Moderate

Drug contraindication overview.

No enhanced Contraindications information available for this drug.

There are 0 contraindications.

There are 6 severe contraindications. Adequate patient monitoring is recommended for safer drug use.

Severe List
Angle-closure glaucoma
Benign prostatic hyperplasia
Bladder outflow obstruction
Chronic idiopathic constipation
Stenosing peptic ulcer
Urinary retention

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
Coronary artery disease
Hypertension
Hyperthyroidism
Ocular hypertension
Pyloroduodenal obstruction
Seizure disorder

The following adverse reaction information is available for DRIMINATE (dimenhydrinate):

Overview
Severe
Less Severe

Adverse reaction overview.

No enhanced Common Adverse Effects information available for this drug.

There are 8 severe adverse reactions.

More Frequent	Less Frequent
None.	None.

Rare/Very Rare
Anaphylaxis Blood dyscrasias Extrasystoles Hallucinations Hemolytic anemia Hypersensitivity drug reaction Hypotension Seizure disorder

There are 52 less severe adverse reactions.

More Frequent	Less Frequent
Anticholinergic toxicity Dizziness Drowsy Thick bronchial secretions	Muscle weakness Sedation

Rare/Very Rare
Abdominal distension Accidental fall Acute abdominal pain Acute cognitive impairment Agitation Anorexia Ataxia Blurred vision Chest discomfort Chills Constipation Diarrhea Diplopia Dry nose Dry throat Dyspnea Dysuria Euphoria Excitement Fatigue Headache disorder Hyperhidrosis Insomnia Irritability Maculopapular rash Malaise Migraine Nausea Nervousness Nightmares Palpitations Paresthesia Pruritus of skin Skin photosensitivity Skin rash Symptoms of anxiety Tachycardia Tinnitus Tremor Urinary retention Urticaria Vertigo Visual changes Vomiting Wheezing Xerostomia

Rare/Very Rare

Abdominal distension
Accidental fall
Acute abdominal pain
Acute cognitive impairment
Agitation
Anorexia
Ataxia
Blurred vision
Chest discomfort
Chills
Constipation
Diarrhea
Diplopia
Dry nose
Dry throat
Dyspnea
Dysuria
Euphoria
Excitement
Fatigue
Headache disorder
Hyperhidrosis
Insomnia
Irritability
Maculopapular rash
Malaise
Migraine
Nausea
Nervousness
Nightmares
Palpitations
Paresthesia
Pruritus of skin
Skin photosensitivity
Skin rash
Symptoms of anxiety
Tachycardia
Tinnitus
Tremor
Urinary retention
Urticaria
Vertigo
Visual changes
Vomiting
Wheezing
Xerostomia

The following precautions are available for DRIMINATE (dimenhydrinate):

Pediatric
Pregnant
Lactation
Geriatric

No enhanced Pediatric Use information available for this drug.

Contraindicated

None

Severe Precaution

None

Management or Monitoring Precaution

None

Reproduction studies in rats and rabbits using dimenhydrinate doses up to 20 and 25 times the human dose (on a mg/kg basis), respectively, have not revealed evidence of harm to the fetus. There are no adequate and well-controlled studies using dimenhydrinate in pregnant women. Clinical studies to date in pregnant women receiving the drug have not indicated an increased risk of abnormalities when administered during any trimester. Although the possibility of harm to the fetus appears remote, dimenhydrinate should be used during pregnancy only when clearly needed.

Small amounts of dimenhydrinate are distributed into milk. Because of the potential for adverse reactions to dimenhydrinate in nursing infants, a decision should be made whether to discontinue nursing or the drug, taking into account the importance of the drug to the woman.

No enhanced Geriatric Use information available for this drug.

The following icd codes are available for DRIMINATE (dimenhydrinate)'s list of indications:

Motion sickness
T75.3xxA	Motion sickness, initial encounter
Nausea
R11	Nausea and vomiting
R11.0	Nausea
R11.2	Nausea with vomiting, unspecified
Nausea and vomiting
R11	Nausea and vomiting
R11.2	Nausea with vomiting, unspecified
Vertigo
A88.1	Epidemic vertigo
H81.1	Benign paroxysmal vertigo
H81.10	Benign paroxysmal vertigo, unspecified ear
H81.11	Benign paroxysmal vertigo, right ear
H81.12	Benign paroxysmal vertigo, left ear
H81.13	Benign paroxysmal vertigo, bilateral
H81.2	Vestibular neuronitis
H81.20	Vestibular neuronitis, unspecified ear
H81.21	Vestibular neuronitis, right ear
H81.22	Vestibular neuronitis, left ear
H81.23	Vestibular neuronitis, bilateral
H81.3	Other peripheral vertigo
H81.31	Aural vertigo
H81.311	Aural vertigo, right ear
H81.312	Aural vertigo, left ear
H81.313	Aural vertigo, bilateral
H81.319	Aural vertigo, unspecified ear
H81.39	Other peripheral vertigo
H81.391	Other peripheral vertigo, right ear
H81.392	Other peripheral vertigo, left ear
H81.393	Other peripheral vertigo, bilateral
H81.399	Other peripheral vertigo, unspecified ear
H81.4	Vertigo of central origin
H82	Vertiginous syndromes in diseases classified elsewhere
H82.1	Vertiginous syndromes in diseases classified elsewhere, right ear
H82.2	Vertiginous syndromes in diseases classified elsewhere, left ear
H82.3	Vertiginous syndromes in diseases classified elsewhere, bilateral
H82.9	Vertiginous syndromes in diseases classified elsewhere, unspecified ear
R42	Dizziness and giddiness
T75.23	Vertigo from infrasound
T75.23xA	Vertigo from infrasound, initial encounter
Vomiting
K91.0	Vomiting following gastrointestinal surgery
R11	Nausea and vomiting
R11.1	Vomiting
R11.10	Vomiting, unspecified
R11.11	Vomiting without nausea
R11.12	Projectile vomiting
R11.13	Vomiting of fecal matter
R11.14	Bilious vomiting
R11.15	Cyclical vomiting syndrome unrelated to migraine
R11.2	Nausea with vomiting, unspecified