Hydralazine

Essential hypertension, alone or as an adjunct.

Initiate therapy in gradually increasing dosages; adjust according to individual response. Start with 10 mg four times daily for the first 2 to 4 days, increase to 25 mg four times daily for the balance of the first week. For the second and subsequent weeks, increase dosage to 50 mg four times daily.

For maintenance, adjust dosage to the lowest effective levels. The incidence of toxic reactions, particularly the L.E. cell syndrome, is high in the group of patients receiving large doses of hydralazine hydrochloride tablets. In a few resistant patients, up to 300 mg of hydralazine hydrochloride tablets daily may be required for a significant antihypertensive effect.

In such cases, a lower dosage of hydralazine hydrochloride tablets combined with a thiazide and/or reserpine or a beta blocker may be considered. However, when combining therapy, individual titration is essential to ensure the lowest possible therapeutic dose of each drug.

In a few patients hydralazine may produce a clinical picture simulating systemic lupus erythematosus including glomerulonephritis. In such patients hydralazine should be discontinued unless the benefit-to-risk determination requires continued antihypertensive therapy with this drug. Symptoms and signs usually regress when the drug is discontinued but residua have been detected many years later.

Long-term treatment with steroids may be necessary.

Hypersensitivity to hydralazine; coronary artery disease; mitral valvular rheumatic heart disease.

Pregnancy Teratogenic Effects Pregnancy Category C Animal studies indicate that hydralazine is teratogenic in mice at 20 to 30 times the maximum daily human dose of 200 to 300 mg and possibly in rabbits at 10 to 15 times the maximum daily human dose, but that it is nonteratogenic in rats. Teratogenic effects observed were cleft palate and malformations of facial and cranial bones. There are no adequate and well-controlled studies in pregnant women.

Although clinical experience does not include any positive evidence of adverse effects on the human fetus, hydralazine should be used during pregnancy only if the expected benefit justifies the potential risk to the fetus.

Nursing Mothers Hydralazine has been shown to be excreted in breast milk.

Adverse reactions with hydralazine are usually reversible when dosage is reduced. However, in some cases it may be necessary to discontinue the drug. The following adverse reactions have been observed, but there has not been enough systematic collection of data to support an estimate of their frequency.

Common headache, anorexia, nausea, vomiting, diarrhea, palpitations, tachycardia, angina pectoris. Less Frequent Digestive constipation, paralytic ileus. Cardiovascular hypotension, paradoxical pressor response, edema. Respiratory dyspnea. Neurologic peripheral neuritis, evidenced by paresthesia, numbness, and tingling, dizziness; tremors; muscle cramps; psychotic reactions characterized by depression, disorientation, or anxiety.

Genitourinary difficulty in urination. Hematologic blood dyscrasias, consisting of reduction in hemoglobin and red cell count, leukopenia, agranulocytosis, purpura, lymphadenopathy; splenomegaly. Hypersensitive Reactions rash, urticaria, pruritus, fever, chills, arthralgia, eosinophilia, and rarely, hepatitis.

Other nasal congestion, flushing, lacrimation, conjunctivitis.