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Uses

Hypertension

Management of hypertension (alone or in combination with other classes of antihypertensive agents).

Can be used as monotherapy for initial management of uncomplicated hypertension; however, thiazide diuretics are preferred by JNC 7.

Do not use for the treatment of hypertension in patients with left ventricular hypertrophy.

Hypertensive Crises

Parenteral drug of choice for management of pregnancy-associated hypertensive emergencies (e.g., preeclampsia, eclampsia) when delivery is imminent.

Parenteral management of severe hypertension when the drug cannot be given orally or when BP must be lowered immediately; other parenteral hypotensive agents (e.g., sodium nitroprusside) usually are preferred for these indications.

Not recommended for the management of severe hypertension or hypertensive emergencies associated with cerebrovascular accidents or in patients with cerebral edema and encephalopathy.

Although some manufacturers have not established pediatric dosage recommendations, some clinicians suggest the IV or IM use of hydralazine for rapid reduction of BP in pediatric patients 1–17 years of age† with hypertensive urgencies or emergencies.†

CHF: Fixed-combination Therapy with Isosorbide Dinitrate in Self-identified Black Patients

In fixed combination with isosorbide dinitrate as adjunct to standard therapy for the treatment of CHF in self-identified black patients to improve survival, decrease rate of hospitalization for worsened heart failure, and improve patient-reported functional status.

CHF: Other Therapies in the General Population

Hydralazine (in combination with cardiac glycosides and diuretics and/or with isosorbide dinitrate) has been used effectively for the treatment of CHF†; should be considered particularly in those intolerant of ACE inhibitors.

There is little evidence to support the use of hydralazine alone in the treatment of CHF†.

Dosage and Administration

General

Hypertension

• Fixed combination with a thiazide diuretic is not recommended for initial combination therapy; adjust initial and subsequent dosages by administering each drug separately.
• Adjust dosage carefully according to individual requirements and BP response at approximately monthly intervals or more aggressively in high-risk patients.
• Tolerance to antihypertensive effect develops during prolonged therapy, especially if a diuretic is not administered concurrently.
• Administer lowest effective dosage to minimize risk and occurrence of adverse effects.

Hypertensive Crises

• Monitor BP closely when parenteral hydralazine is used.
• Avoid excessive BP decreases in any hypertensive crisis since they may precipitate renal, cerebral, or coronary ischemia.
• Avoid abrupt discontinuance in patients with a marked reduction in BP. To minimize risk for sudden BP increase, reduce dosage gradually.

Administration

Administer orally or by IM or IV injection. Usually administer orally; may be administered IM or IV if patient unable to take drug orally or if a rapid decrease in BP is required.

Oral Administration

Administer orally 2–4 times daily.

IV Administration

For solution and drug compatibility information, see Compatibility under Stability.

Administer by rapid IV injection directly into the vein.

Replace parenteral therapy with oral therapy as soon as possible.

Dosage

Available as hydralazine hydrochloride; dosage expressed in terms of the salt.

20–25 mg of IV hydralazine hydrochloride was approximately equal to 75–100 mg of oral hydralazine hydrochloride in one study.

Pediatric Patients

Hypertension

Oral

Initially, 0.75 mg/kg daily (or 25 mg/m² daily) given in 4 divided doses; initial dose should not exceed 25 mg.†

Dosages may be increased gradually (over 3–4 weeks) up to a maximum of 7.5 mg/kg daily (or 200 mg daily).†

IM or IV

Usual dosage: 1.7–3.5 mg/kg daily or 50–100 mg/m² daily given in 4–6 divided doses; initial dose should not exceed 20 mg.†

If administered with reserpine, hydralazine hydrochloride dosages may be reduced to 0.15 mg/kg or 4 mg/m² every 12–24 hours.†

Hypertensive Urgencies or Emergencies

Rapid Reduction of BP

IV or IM

Children and adolescents 1–17 years of age: 0.2–0.6 mg/kg IV or IM per dose; administer every 4 hours when given by IV bolus injection.†

Hypertensive Crises

IM or IV

For rapid reduction of blood pressure in patients 1–17 years of age with severe hypertension, some clinicians have suggested a dose of 0.2–0.6 mg/kg; drug should be administered every 4 hours when given by injection (“IV bolus”).†

Adults

Hypertension

Monotherapy

Oral

Initially, 10 mg 4 times daily for 2–4 days. 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. Usual dosages of 12.5–50 mg twice daily recommended by JNC 7.

Combination Therapy

Oral

If BP is not adequately controlled by monotherapy with hydalazine or hydrochlorothiazide, can switch to fixed-combination capsules containing hydralazine hydrochloride 25 mg and hydrochlorothiazide 25 mg; then hydralazine hydrochloride 50 mg and hydrochlorothiazide 50 mg, administered twice daily.

Hypertensive Crises

Management of Hypertensive Emergencies

IM or IV

Usual dose: 20–40 mg. Parenteral doses are repeated as necessary and may be increased within these ranges according to the BP response.

Initial goal of therapy is to reduce mean arterial BP by no more than 25% (within minutes to 1 hour), then, if stable, to 160/100 to 110 mm Hg within the next 2 to 6 hours.

If this BP is well tolerated and the patient is clinically stable, implement further gradual reductions toward normal in the next 24–48 hours. In patients with aortic dissection, reduce SBP to less than 100 mm Hg if tolerated.

Management of Pregnancy-associated Hypertensive Emergencies

Antihypertensives are administered before induction of labor for persistent DBP ≥105–110 mm Hg, aiming for levels of 95–105 mm Hg.

In pregnant women, DBP >109 mm Hg are associated with an increased risk of cerebral hemorrhage.

IV

Usual initial dose: 5–10 mg, followed by 5–10 mg (range: 5–20 mg) every 20–30 minutes as necessary to achieve an adequate BP reduction.

CHF

Fixed-combination Therapy with Isosorbide Dinitrate in Self-identified Black Patients

Oral

Initially, hydralazine hydrochloride 37.5 mg and isosorbide dinitrate 20 mg (1 tablet of BiDil^®) 3 times daily. May titrate dosage to a maximum tolerated dosage not to exceed 2 tablets (a total of 75 mg of hydralazine hydrochloride and 40 mg of isosorbide dinitrate) 3 times daily. Rapid titration (over 3–5 days) may be possible; however, slower titration may be needed due to adverse effects. May decrease dosage to as little as one-half of the fixed-combination tablet 3 times daily in patients who experience intolerable effects, but attempt to titrate dosage up once adverse effects subside.

Prescribing Limits

Pediatric Patients

Hypertension

Oral

Maximum 7.5 mg/kg daily (or 200 mg daily).

Adults

Hypertension

Maintenance Therapy

Oral

Maximum 100 mg daily; addition of another antihypertensive agent is preferable to increasing dosage beyond 100 mg because of poor patient tolerance.

CHF

Fixed-combination Therapy with Isosorbide Dinitrate in Self-identified Black Patients

Oral

Maximum 75 mg of hydralazine hydrochloride and 40 mg of isosorbide dinitrate (2 tablets of BiDil^®) 3 times daily.

Special Populations

Dosage in Renal Impairment

Lower dosage may be required in severe renal failure.

Geriatric Patients

The manufacturer of the fixed combination of hydralazine hydrochloride and isosorbide dinitrate states that dosage should be selected with caution because of age-related decreases in hepatic, renal, and/or cardiac function and concomitant disease and drug therapy.