A Randomized, Double-Blind Comparison of the Efficacy and Tolerability of Once-Daily Modified-Release Diltiazem Capsules with Once-Daily Amlodipine Tablets in Patients with Stable Angina

A randomized, double-blind, parallel-group study comparing the efficacy and tolerability of once-daily diltiazem capsules with amlodipine tablets in patients with stable angina. After a run-in period of 1 to 3 weeks, 34 patients received once-daily diltiazem and 33 patients received amlodipine. Patients received either diltiazem, 240 mg/day, or amlodipine, 5 mg/day, for 2 weeks followed by diltiazem, 360 mg/day, or amlodipine, 10 mg/day, for 2 weeks. Standard treadmill exercise testing was the primary efficacy assessment. Patients also recorded incidence of angina attacks and use of glyceryl trinitrate spray. Both treatments gave significant improvement in time to onset of angina and time to maximal exercise. With the exception of amlodipine, 5 mg/day, both treatments gave significant increases in time to 1-mm ST segment depression. Diltiazem, 360 mg/day, gave a significant decrease in rate pressure product. There were no significant treatment differences in any of the exercise test parameters. Both treatments reduced incidence of angina attacks and use of glyceryl trinitrate spray. The incidence of edema was significantly less in patients receiving diltiazem. In conclusion, both treatments were effective in controlling patients' angina, but diltiazem was better tolerated, with a lower incidence of edema.