Safety and efficacy of diltiazem hydrochloride for the treatment of stable angina pectoris: report of a cooperative clinical trial.

Sixty-three patients completed a multicenter 10 week, double-blind, parallel group protocol evaluating the efficacy of diltiazem versus placebo with respect to rate of attacks of angina, nitroglycerin consumption and duration of treadmill exercise. An additional 36 patients were evaluated for drug safety. A 4 week placebo lead-in phase was followed by a 2 week dose titration period and two treatment evaluation periods of 2 weeks each. Both diltiazem and placebo were associated with a significant reduction in weekly frequency of angina from the baseline rate. Intergroup comparison disclosed a significantly greater reduction for the patients receiving diltiazem than for those receiving placebo. A similar reduction was noted for nitroglycerin consumption. Total exercise duration at week 10 was statistically greater in patients treated with diltiazem. Diltiazem was well tolerated. No abnormalities in hematologic profiles or in routine serum chemistry values were observed; electrocardiographic P-R and QRS intervals were unaffected. Adverse effects that could have been related to drug administration were reported in 11 patients who received diltiazem and in 12 patients who received placebo. Of the 17 episodes in the diltiazem group only 3 were considered significant and drug-related, and only one of these resulted in discontinuation of the drug.