Hydrallazine with beta-blocker and diuretic in the treatment of hypertension. A double-blind crossover study.

Thirty-seven hypertensive patients were treated with cyclopenthiazide, oxprenolol and hydrallazine. Blood pressure was controlled in 31 patients and a subsequent double-blind crossover study in 27 patients comparing hydrallazine with placebo confirmed the efficacy of hydrallazine in combination with diuretic and beta-adrenergic-blocking agent. The combination was effective in patients with renal hypertension and renal impairment. No adverse effects on renal function were observed. Patients who were slow acetylators had significantly better blood pressure control and more side effects. In view of the frequency of hydrallazine related side effects, prior institution of beta-adrenergic blocking drugs is desirable.