Comparison of diltiazem standard formulation and diltiazem controlled release in patients with stable angina pectoris: a randomized, double-blind, cross-over, multicenter study.

In a randomized, double-blind, cross-over, multicenter study with a placebo run-in phase, the efficacy and safety of two oral formulations of diltiazem, standard three or four times daily (t.i.d. or q.i.d.) and controlled release twice daily (b.i.d.), were compared in 49 patients with stable angina pectoris. ST-segment depression at maximum exercise 12 h after tablet intake was less frequently observed with diltiazem controlled release than with standard diltiazem (34 of 49, 69% vs. 43 of 49, 88%, p = 0.007). In patients with ST-segment depression after both treatments (n = 33), the average time to 1-mm ST-segment depression was 55.4 +/- 19.9 s longer with diltiazem controlled release than with standard diltiazem [476 +/- 195 vs. 422 +/- 163 s, p = 0.009; 95% confidence interval (CI) 14.8-96 s]. Reduction in mean number of anginal attacks and nitroglycerin (NTG) intake was not significantly different between treatment with standard diltiazem and diltiazem controlled release. The incidence of side effects was low and not different between the two treatments. Both formulations are equally effective in reducing the number of anginal attacks and are well tolerated. Diltiazem controlled release is more effective than standard diltiazem in preventing myocardial ischemia 12 h after tablet intake. Thus, diltiazem controlled release allows twice-daily intake frequency and may therefore be preferable to standard diltiazem in treatment of stable angina pectoris.