Efficacy of sustained-release verapamil in chronic stable angina pectoris.

The effectiveness of a sustained-release preparation of verapamil (verapamil-SR) was compared with the regular formulation of verapamil and with placebo in 12 patients with chronic stable angina pectoris. All patients completed an 8-week, double-blind, double-crossover, randomized protocol with 2-week treatment periods of verapamil-SR, 240 mg twice daily; regular-formulation verapamil, 120 mg 4 times daily; and 2 placebo therapies. The frequency of weekly anginal episodes was reduced from 7.6 +/- 10.0 with placebo to 3.1 +/- 4.2 after the regular formulation of verapamil (p = 0.09) and from 6.4 +/- 7.6 with placebo to 2.8 +/- 4.8 after verapamil-SR (p = 0.06). Treadmill time increased from 384 +/- 144 seconds during the first placebo phase to 468 +/- 138 seconds after the regular formulation of verapamil (p less than 0.01) and from 354 +/- 102 seconds during the second placebo phase to 462 +/- 138 seconds after verapamil-SR (p less than 0.01). Time to the onset of angina was similarly prolonged by formulations of verapamil. There were no significant adverse effects after 1 year in any patient taking verapamil-SR, 240 mg twice daily. Thus, a twice-a-day verapamil-SR dose regimen is safe and is as effective for treatment of angina of effort as the regular formulation given 4 times a day.