Hydralazine Hcl

Drug overview for HYDRALAZINE HCL (hydralazine hcl):

Generic name: hydralazine HCl (hye-DRAL-a-zeen)
Drug class: Vasodilators
Therapeutic class: Cardiovascular Therapy Agents

Hydralazine hydrochloride is a vasodilating agent.

No enhanced Uses information available for this drug.

DRUG IMAGES

HYDRALAZINE 50 MG TABLET
HYDRALAZINE 10 MG TABLET
HYDRALAZINE 25 MG TABLET
HYDRALAZINE 100 MG TABLET

The following indications for HYDRALAZINE HCL (hydralazine hcl) have been approved by the FDA:

Indications:
Hypertension

Professional Synonyms:
Elevated blood pressure
Essential hypertension
Hyperpiesia
Hyperpiesis
Hypertensive disorder
Systemic arterial hypertension

The following dosing information is available for HYDRALAZINE HCL (hydralazine hcl):

Dosing
Administration
HYDRALAZINE HCL
HYDRALAZINE HCL

When hydralazine therapy is discontinued in patients with a marked reduction in blood pressure, withdrawal should be gradual to avoid a possible sudden increase in blood pressure. One study found 20-25 mg of IV hydralazine hydrochloride approximately equal to 75-100 mg of oral hydralazine hydrochloride.

For the management of hypertension, an initial adult oral dosage of hydralazine hydrochloride of 10 mg 4 times daily for 2-4 days has been suggested. Dosage then can be increased to 25 mg 4 times daily for the remainder of the week. If necessary, dosage can be increased for the second and subsequent weeks to 50 mg 4 times daily.

In a few patients, 300-400 mg daily may be required. Generally, slow acetylators should not receive more than 200 mg daily of oral hydralazine hydrochloride. For maintenance therapy, dosage is adjusted to the lowest effective level.

Studies have shown hydralazine may be administered twice daily in many patients for maintenance therapy. Some experts state that the usual dosage range is 100-200 mg daily, administered in 2 or 3 divided doses.

Although the manufacturers state that pediatric dosage recommendations have not been established in controlled clinical trials, there is experience with the use of hydralazine hydrochloride in pediatric patients. Based on such experience, an initial oral hydralazine hydrochloride dosage of 0.75 mg/kg daily given in 4 divided doses has been suggested for treatment of hypertension.

If necessary, oral dosage may be increased gradually over a period of 3-4 weeks up to a maximum of 7.5 mg/kg (or 200 mg) daily. For information on overall principles and expert recommendations for treatment of hypertension in pediatric patients, see Uses: Hypertension in Pediatric Patients, in the Thiazides General Statement 40:28.20.

Patients with severe renal failure may require a lower dosage of hydralazine.

Hydralazine hydrochloride usually is administered orally. In patients who are unable to take the drug orally or when a rapid decrease in blood pressure is required, the drug may be given IM or IV. Oral therapy with hydralazine should replace parenteral therapy as soon as possible.

Dosing information for HYDRALAZINE HCL
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
HYDRALAZINE 25 MG TABLET	Maintenance	Adults take 1 tablet (25 mg) by oral route 2 times per day with food
HYDRALAZINE 50 MG TABLET	Maintenance	Adults take 1 tablet (50 mg) by oral route 2 times per day with food
HYDRALAZINE 100 MG TABLET	Maintenance	Adults take 1 tablet (100 mg) by oral route 2 times per day with food
HYDRALAZINE 10 MG TABLET	Maintenance	Adults take 1 tablet (10 mg) by oral route 2 times per day with food

Generic dosing information for HYDRALAZINE HCL
DRUG LABEL	DOSING TYPE	DOSING INSTRUCTIONS
HYDRALAZINE 10 MG TABLET	Maintenance	Adults take 1 tablet (10 mg) by oral route 2 times per day with food
HYDRALAZINE 25 MG TABLET	Maintenance	Adults take 1 tablet (25 mg) by oral route 2 times per day with food
HYDRALAZINE 50 MG TABLET	Maintenance	Adults take 1 tablet (50 mg) by oral route 2 times per day with food
HYDRALAZINE 100 MG TABLET	Maintenance	Adults take 1 tablet (100 mg) by oral route 2 times per day with food

The following drug interaction information is available for HYDRALAZINE HCL (hydralazine hcl):

Contraindicated
Severe
Moderate

There are 0 contraindications.

There are 0 severe interactions.

There are 5 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
Selected MAOIs/Selected Antihypertensive Agents SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Both MAOIs and antihypertensive agents may increase the risk of postural hypotension.(1,2) CLINICAL EFFECTS: Postural hypotension may occur with concurrent therapy of MAOIs and antihypertensive agents.(1,2) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: The manufacturer of phenelzine states all patients should be followed closely for symptoms of postural hypotension. Hypotensive side effects have occurred in patients who have been hypertensive and normotensive, as well as hypotensive at initiation of phenelzine.(1) The manufacturer of tranylcypromine states hypotension has been observed most commonly but not exclusively in patients with pre-existing hypertension. Tranylcypromine doses greater than 30 mg daily have a major side effect of postural hypotension and can lead to syncope. Gradual dose titration is recommended to decrease risk of postural hypotension. Combined use with other agents known to cause hypotension have shown to have additive side effects and should be monitored closely.(2) Monitor the patient for signs and symptoms of postural hypotension including dizziness, lightheadedness, or weakness, especially upon standing. Monitor blood pressure as well as orthostatic vitals and adjust antihypertensive therapy, including decreasing the dose, dividing doses, or scheduling doses at bedtime, as needed to maintain goal blood pressure. If blood pressure remains hypotensive, consider decreasing the dose of phenelzine or tranylcypromine. In some cases, discontinuation of one or both agents may be necessary.(3) Normotensive patients on stable antihypertensive therapy who are started on either phenelzine or tranylcypromine may be at increased risk for hypotension. Hypertensive patients on stable phenelzine or tranylcypromine who require antihypertensive therapy would be at decreased risk for hypotension. DISCUSSION: A review article describes the pharmacology of phenelzine and tranylcypromine as non-selective MAOIs which inhibit both type A and type B substrates. Orthostatic hypotension is described as the most common MAOI side effect and usually occurs between initiation and the first 3-4 weeks of therapy.(3) In a double-blind study, 71 patients were randomized to receive a 4-week trial of either tranylcypromine, amitriptyline, or the combination. The number of patients reporting dizziness at 4 weeks was not different between the three treatment groups (tranylcypromine 52.4%; amitriptyline 65%; combination 66.7%). Blood pressure (BP) assessment noted a significant drop in standing BP in the tranylcypromine group compared to baseline (systolic BP change = -10 mmHg; p<0.02 and diastolic BP change = -9 mmHg; p<0.02). Combination therapy also had a significant drop in standing BP compared to baseline (systolic BP change = -9 mmHg; p<0.02). Patients receiving amitriptyline had no significant change in BP from baseline at 4 weeks. All three groups had a trend toward increasing orthostatic hypotension in BP changes from lying to standing. The change in orthostatic hypotension was significant in the amitriptyline group with an average systolic BP orthostatic drop of -9 mmHg (p<0.05).(4) A randomized, double-blind study of 16 inpatients with major depressive disorder were treated with either phenelzine or tranylcypromine. Cardiovascular assessments were completed at baseline and after 6 weeks of treatment. After 6 weeks, 5/7 patients (71%) who received phenelzine had a decrease in standing systolic BP greater than 20 mmHg from baseline. Head-up tilt systolic and diastolic BP decreased from baseline in patients on phenelzine (98/61 mmHg v. 127/65 mmHg, respectively; systolic change p=0.02 and diastolic change p=0.02). After 6 weeks, 6/9 patients (67%) who received tranylcypromine had a decrease in standing systolic BP greater than 20 mmHg from baseline. Head-up tilt systolic and diastolic BP decreased from baseline in patients on tranylcypromine (113/71 mmHg v. 133/69 mmHg, respectively; systolic change p=0.09 and diastolic change p=0.07).(5) Selected MAOIs linked to this monograph include: phenelzine and tranylcypromine. Selected antihypertensive agents include: ACE inhibitors, alpha blockers, ARBs, beta blockers, calcium channel blockers, aprocitentan, clonidine, hydralazine and sparsentan.	NARDIL, PARNATE, PHENELZINE SULFATE, TRANYLCYPROMINE SULFATE
Tizanidine/Selected Antihypertensives SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Tizanidine is an alpha-2 agonist. Concurrent use with antihypertensive agents may result in additive effects on blood pressure.(1) CLINICAL EFFECTS: Concurrent use of antihypertensives and tizanidine may result in hypotension.(1) PREDISPOSING FACTORS: None determined. PATIENT MANAGEMENT: Patients receiving concurrent therapy should be monitored for hypotension. The risk of hypotension may be decreased by careful titration of tizanidine dosages and monitoring for hypotension prior to dose advancement. Counsel patients about the risk of orthostatic hypotension.(1) DISCUSSION: Severe hypotension has been reported following the addition of tizanidine to existing lisinopril therapy.(2-4)	TIZANIDINE HCL, ZANAFLEX
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
Apomorphine/Selected Antihypertensives and Vasodilators SEVERITY LEVEL: 3-Moderate Interaction: Assess the risk to the patient and take action as needed. MECHANISM OF ACTION: Apomorphine causes dose-dependent decreases in blood pressure. Concurrent use with antihypertensive agents may result in additive effects on blood pressure.(1) CLINICAL EFFECTS: Concurrent use of antihypertensives and apomorphine may result in orthostatic hypotension with or without dizziness, nausea, or syncope.(1) PREDISPOSING FACTORS: The risk of orthostatic hypotension may be increased during dose escalation of apomorphine and in patients with renal or hepatic impairment.(1) PATIENT MANAGEMENT: Patients receiving concurrent therapy should be monitored for hypotension. Counsel patients about the risk of orthostatic hypotension.(1) DISCUSSION: Healthy volunteers who took sublingual nitroglycerin (0.4 mg) concomitantly with apomorphine experienced a mean largest decrease in supine systolic blood pressure (SBP) of 9.7 mm Hg and in supine diastolic blood pressure (DBP) of 9.3 mm Hg, and a mean largest decrease in standing SBP and DBP of 14.3 mm Hg and 13.5 mm Hg, respectively. The maximum decrease in SBP and DBP was 65 mm Hg and 43 mm Hg, respectively. When apomorphine was taken alone, the mean largest decrease in supine SBP and DBP was 6.1 mm Hg and 7.3 mm Hg, respectively, and in standing SBP and DBP was 6.7 mm Hg and 8.4 mm Hg, respectively.(1)	APOKYN, APOMORPHINE HCL, ONAPGO

The following contraindication information is available for HYDRALAZINE HCL (hydralazine hcl):

Overview
Contraindicated
Severe
Moderate

Drug contraindication overview.

No enhanced Contraindications information available for this drug.

There are 0 contraindications.

There are 5 severe contraindications. Adequate patient monitoring is recommended for safer drug use.

Severe List
30 day risk period post-myocardial infarction
Coronary artery disease
Hypotension
Hypovolemia
Slow acetylator due to n-acetyltransferase enzyme variant

There are 3 moderate contraindications. Clinically significant contraindication, where the condition can be managed or treated before the drug may be given safely.

Moderate List
Cerebrovascular accident
Intracranial hypertension
Lupus-like syndrome

The following adverse reaction information is available for HYDRALAZINE HCL (hydralazine hcl):

Overview
Severe
Less Severe

Adverse reaction overview.

No enhanced Common Adverse Effects information available for this drug.

There are 17 severe adverse reactions.

More Frequent	Less Frequent
None.	Angina Edema Lupus-like syndrome Peripheral neuropathy Pruritus of skin Skin rash Urticaria

Rare/Very Rare
Agranulocytosis Anemia Eosinophilia Glomerulonephritis Hepatitis Leukopenia Lymphadenopathy Paralytic ileus Purpura Splenomegaly

There are 26 less severe adverse reactions.

More Frequent	Less Frequent
Anorexia Diarrhea Headache disorder Nausea Palpitations Tachycardia Vomiting	Constipation Dizziness Dyspnea Eye tearing Flushing Hypotension Nasal congestion

Rare/Very Rare
Accidental fall Acute cognitive impairment Anticholinergic toxicity Arthralgia Chills Conjunctivitis Depression Dysuria Fever Peripheral neuritis Symptoms of anxiety Tremor

The following precautions are available for HYDRALAZINE HCL (hydralazine hcl):

Pediatric
Pregnant
Lactation
Geriatric

No enhanced Pediatric Use information available for this drug.

Contraindicated

None

Severe Precaution

None

Management or Monitoring Precaution

None

Safe use of hydralazine in pregnancy has not been established. Hydralazine is teratogenic in mice and possibly in rabbits but not in rats. Teratogenic effects in animals have included cleft palate and malformation of facial and cranial bones.

A meta-analysis of randomized, controlled trials comparing hydralazine with other antihypertensive agents for the treatment of severe hypertension during pregnancy showed that hydralazine was associated with a higher incidence of maternal hypotension, placental abruption, cesarean sections, and oliguria, as well as a higher incidence of lower Apgar scores and adverse effects on fetal heart rate than the other hypotensive drugs. In one study in 13 pregnant women with long-standing hypertension during 15 pregnancies who received combination therapy with hydralazine and propranolol, 14 live births and one unexplained stillbirth were reported. The only neonatal complications observed were 2 cases of mild hypoglycemia.

In patients receiving hydralazine during pregnancy, the drug and its metabolites have been detected in maternal and umbilical plasma using a nonselective assay. The manufacturers state that although clinical experience with the drug does not indicate any positive evidence of adverse effect on the human fetus to date, hydralazine should not be used during pregnancy unless the possible benefits outweigh the potential risks to the fetus.

It is not known whether hydralazine is distributed into breast milk. Because many drugs are distributed into milk, the drug should be used with caution in nursing women.

No enhanced Geriatric Use information available for this drug.

The following icd codes are available for HYDRALAZINE HCL (hydralazine hcl)'s list of indications:

Hypertension
I10	Essential (primary) hypertension
I11	Hypertensive heart disease
I11.0	Hypertensive heart disease with heart failure
I11.9	Hypertensive heart disease without heart failure
I12	Hypertensive chronic kidney disease
I12.0	Hypertensive chronic kidney disease with stage 5 chronic kidney disease or end stage renal disease
I12.9	Hypertensive chronic kidney disease with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease
I13	Hypertensive heart and chronic kidney disease
I13.0	Hypertensive heart and chronic kidney disease with heart failure and stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease
I13.1	Hypertensive heart and chronic kidney disease without heart failure
I13.10	Hypertensive heart and chronic kidney disease without heart failure, with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease
I13.11	Hypertensive heart and chronic kidney disease without heart failure, with stage 5 chronic kidney disease, or end stage renal disease
I13.2	Hypertensive heart and chronic kidney disease with heart failure and with stage 5 chronic kidney disease, or end stage renal disease
I15.1	Hypertension secondary to other renal disorders