Verapamil versus placebo in relieving stable angina pectoris.

Verapamil and placebo were compared in patients with stable, effort-induced angina. Single-blind dose titration (240, 360 and 480 mg/day) preceded a double-blind crossover. Among the 18 patients who completed graded exercise stress tests with reproducible pretreatment effort-limiting angina, exercise duration increased from 348 +/- 127 seconds (SD) before treatment to 494 +/- 182 seconds after verapamil (p less than 0.001), but did not change after placebo. Compared with placebo, verapamil reduced the weekly number of anginal episodes from 4.54 +/- 5.03 to 2.44 +/- 3.30 (p less than 0.05) and reduced nitroglycerin consumption from 3.46 +/- 5.30 to 1.55 +/- 2.89 tablets per week (p less than 0.05). Of 26 patients who completed the single-blind dose titration, 16 were improved (greater than 1 minute) at a dosage of 240 or 360 mg/day. No patient improved (greater than 1 minute) on 480 mg/day who had not already improved on a lower dose, but side effects requiring reduction in dosage occurred in seven patients receiving 480 mg of verapamil per day. Verapamil is an effective antianginal drug that appears most efficacious at a dose of 360 mg/day, but side effects are common at a dose of 480 mg/day.