Evaluation of verapamil and high dose nifedipine in patients with chronic stable angina with objective methods.

The efficacy and safety of verapamil and nifedipine were objectively assessed in patients with chronic stable angina. Twenty four patients entered a double blind randomized cross over trial of nifedipine (10 mg thrice daily) and placebo. In this dosage nifedipine did not show any significant change in exercise duration and the variables obtained using computer assisted exercise testing when compared to placebo. The next stage consisted of another double blind randomized cross over trial comparing the effects of verapamil (120 mg thrice daily) and nifedipine (20 mg thrice daily) with an initial placebo run-in period in 32 patients. At this dose level nifedipine showed a definite and significant improvement in all the objective variables; however an increase in side effects was observed resulting in withdrawal of the drug in seven patients. A common problem was tachycardia precipitating angina after nifedipine ingestion. On the other hand verapamil produced a marked improvement in exercise tolerance and other variables as compared to placebo and nifedipine, was well tolerated and produced a mild bradycardia. This study clearly indicates that verapamil is distinctly superior to nifedipine in efficacy side effects and safety in patients with chronic stable angina. This may be attributable to the differential effect on heart rates induced by these drugs.