Antianginal effect of conventional and controlled release diltiazem in stable angina pectoris

Two preparations of diltiazem, controlled release (CR) given twice a day (b.i.d.) and plain given 4 times a day (q.i.d.), were compared in a multicentre, double-blind, crossover study in 41 patients with stable angina pectoris. Therapeutic efficacy was assessed with maximal exercise tests, patient recordings on nitroglycerine consumption and angina attacks. No significant differences between the CR and plain tablets were seen in any of the efficacy variables. Maximal workload significantly increased from 127 W on placebo to 146 W on CR tablets and to 147 W on plain tablets. Anginal attacks/week significantly decreased from 11.7 on placebo to 4.9 on CR tablets and to 5.0 on plain tablets. Consumption of nitroglycerine tablets/week significantly decreased from 6.3 on placebo to 2.6 and to 3.4 on CR and plain-tablets, respectively. The number or the seriousness of the adverse events did not differ between the groups. The results imply that diltiazem CR b.i.d. is equally potent and safe as conventional diltiazem q.i.d. in the control of stable angina pectoris.