Antianginal efficacy over 24 hours and exercise hemodynamic effects of once daily sustained-release 300 mg diltiazem and 240 mg verapamil in stable angina pectoris

The antianginal efficacy of 240 mg sustained release verapamil once daily doses and 300 mg diltiazem was studied in 20 normotensive patients with chronic stable angina pectoris, using a randomized, double-blind crossover design. Patients received a blinded therapy of verapamil placebo and diltiazem placebo for six weeks than only sustained-release diltiazem (SRD) for a long-term phase of three weeks, after a two-week placebo baseline period. Symptom-limited bycicle exercise was longer with the verapamil (510±129.9 s) and diltiazem (540±124.6 s) than with placebo at baseline (396±152.2 s, P<0.005). Verapamil and diltiazem reduced the weekly rate of anginal attacks from 5.1±8.6 during placebo to 4.4±4.1 with verapamil and 1.9±3.2 with diltiazem (P<0.05). The antianginal effects of the two agents are probably mediated by reduction of myocardial oxygen demand at submaximal exercise. In addition, diltiazem appears to provide more symptomatic relief and reduces the weekly number of anginal attacks significantly more than verapamil. Therefore its once-daily administration simplifies the treatment schedule and should improve patientsʹ compliance.