Calcium antagonists.

Drugs which interfere with the voltage-activated inward displacement of calcium ions into excitable cells, including those of the myocardium, atrial and ventricular nodes, and smooth muscle cells, have become known as calcium antagonists. These drugs are a heterogeneous group, and differ from one another in chemistry, tissue specificity, potency and bioavailability. The prototype of the group is verapamil. Other calcium antagonists are nifedipine and diltiazem. The therapeutic applications of these compounds include the relief of angina pectoris, and the management of hypertension, ischaemic heart disease and, in certain instances, arrhythmias. Calcium antagonists are also useful in the management of oesophageal achalasia, Raynaud's disease, and hypertrophic obstructive cardiomyopathy, and may be of use in premature labour.