The relationship of dose to the antihypertensive response of verapamil-sustained release in patients with mild to moderate essential hypertension. The Verapamil-SR Study Group.

The dose-response relationship of verapamil-SR was studied in 221 hypertensive patients. This double-blind, parallel-group, placebo-controlled study compared placebo to 60 mg, 120 mg, 240 mg and 480 mg daily of verapamil-SR. After 6 weeks of therapy, peak diastolic blood pressure was similar in the placebo group and the verapamil-SR 60 mg group, 93.0 and 92.0 mmHg, respectively. The 120 mg, 240 mg and 480 mg verapamil-SR groups produced significantly lower diastolic blood pressure, 89.8, 85.3 and 83.7 mmHg (P less than 0.01), respectively. At trough, placebo and verapamil-SR 60 mg groups and 120 mg groups had diastolic blood pressures of 96.6, 97.0 and 97.1 mmHg, respectively. Diastolic blood pressure with the 240 mg dose (92.4 mmHg) was significantly lower than with the 120 mg dose (P less than 0.01). The 480 mg dose resulted in a diastolic blood pressure of 88.6 mmHg, which was significantly lower than the 240 mg dose (P less than 0.01). The responder rate with 240 mg at peak was 82%. The trough to peak ratio was 0.58. Plasma concentrations were highly correlated with dose (r greater than 0.8; P less than 0.01); but not with diastolic blood pressure (r greater than 0.4; P less than 0.01). Headache and constipation, although not significantly different from placebo, were the most commonly reported adverse reactions in the verapamil-SR groups, 6.3% (placebo--6.7%) and 5.1% (placebo--4.4%), respectively. Graded doses of verapamil-SR produced a dose-response curve in hypertensive patients with a greater than 80% responder rate at the 240 mg dose.(ABSTRACT TRUNCATED AT 250 WORDS)