Calcium-entry blockers, a class of drugs that increase the heart's blood supply by reducing the spontaneous constriction of cardiac and arterial muscle cells, are finally becoming available for the struggle against heart disease.
The Food and Drug Administration has now approved two of these agents, nifedipine and verapamil, for use orally in the treatment of angina pectoris. One other, diltiazem hydrochloride, is expected to receive FDA approval soon for the same purpose. All three drugs have been used for years in other countries (JAMA [MEDICAL NEWS] 1981;245:807/X 816). The intravenous (IV) form of verapamil was approved in August 1981 for the treatment of some arrhythmias.
Calcium-entry blockers interfere with the mechanism of smooth muscle contraction in the arterial walls. This contraction process is triggered by the entrance of extracellular calcium ions into the muscle cells. The drugs thus can be expected to prevent angina attacks in which arterial spasm plays