Pharmacological differences between calcium antagonists.

The calcium channel antagonists are not an homogeneous group. From both pharmacological and clinical points of view, they can be divided into those of the dihydropyridine family like nifedipine, and those of the non-dihydropyridine family like verapamil and diltiazem. These families bind at different sites to the calcium channel, which may explain some of the clinical differences. The dihydropyridines are more vascular selective and the non-dihydropyridines are more myocardial selective and tend to reduce the heart rate. Further important differences are between short- and long-acting forms of the calcium channel antagonists. From the clinical point of view, these agents are most used in angina pectoris and hypertension. Emerging studies suggest that in angina of effort these agents have a safety record somewhat similar to that of beta-blockers. In congestive heart failure, these agents, as a group, are contraindicated.