Randomized double-blind comparison of isosorbide dinitrate and nifedipine in variant angina pectoris.

The antianginal and anti-ischemic effect of isosorbide dinitrate (ISDN), 120 mg once daily, and nifedipine, 20 mg twice daily, both in slow-release formulations, were compared in 17 patients with variant angina pectoris in a randomized, double-blind trial. The design included a placebo run-in period and two 6-week crossover periods of active treatment. Mean frequency of angina decreased significantly from 43 attacks per week during the placebo period to 4 per week with ISDN and 8 with nifedipine (p less than 0.001). Sublingual nitroglycerin consumption decreased significantly from 37 tablets per week with placebo to 3 tablets per week with ISDN and 7 with nifedipine (p less than 0.001). Both drugs reduced the silent and symptomatic ST-segment deviations on ambulatory electrocardiographic recording and increased maximal exercise tolerance. Episodes of coronary spasm could be provoked, by hyperventilation, in all patients during the placebo phase but in no patient during therapy with either active drug. Thus, both ISDN and nifedipine, in their slow-release formulations, are effective in the treatment of variant angina pectoris.