The safety and efficacy of quinapril in the treatment of mild to moderate essential hypertension

Major clinical trials are reviewed comparing the efficacy and safety of quinapril hydrochloride, a new nonsulfhydryl angiotensin-converting enzyme (ACE) inhibitor, with that of placebo, captopril, and enalapril in the treatment of mild to moderate essential hypertension. A randomized, double-blind 12-week study of 270 patients compared the efficacy of placebo with once or twice daily doses of quinapril (20, 40, 80 mg/day, with forced titration). Quinapril effectively lowered both diastolic blood pressure (DBP) and systolic blood pressure. Mean reductions in DBP of up to 13 mmHg from baseline were obtained. At full dosage, more than 65% of patients achieved a clinically significant reduction in DBP. Quinapril was similarly effective whether the total daily dose was given once or twice daily. In a multicenter, double-blind study involving more than 400 patients, the efficacy of quinapril (10-40 mg/day, given once or twice daily) was found to be similar to captopril (25 mg bid to 50 mg tid). Hydrochlorothiazide (HCTZ) safely provided additive effects when given to nonresponders in both treatment groups. In a 28-week double-blind study of 258 patients comparing the efficacy of quinapril or enalapril at doses of 10, 20, and 40 mg/day (with optional titration), quinapril was found to be of similar efficacy as enalapril. The large majority of patients on either regimen were controlled with monotherapy. HCTZ again safely provided additive effects. Quinapril was well tolerated in all trials, with the incidence of adverse events and withdrawals tending to be lower with quinapril than with enalapril or captopril.