Calcium-channel antagonists: mechanisms of action, vascular selectivities, and clinical relevance

ABSTRACT

The calcium-channel antagonists represent three separate structural categories of drugs. They share a common action—the blockade of calcium-ion flow through one specific type of calcium channel. The chemical heterogeneity of these agents is reflected in their pharmacologic and therapeutic diversity. The calcium-channel antagonists enjoy significant use in cardiovascular medicine for the treatment of hypertension, angina, and some cardiac arrhythmias. However, the 1,4-dihydropyridines, the most potent antihypertensive calcium-channel blockers, lack antiarrhythmic properties. The selectivity of action of calcium-channel antagonists rests upon a number of factors, including pathways of calcium mobilization, types of channel activated, state-dependent interactions, and the pathological state of the tissue. A n understanding of these factors is important to the rational application of these drugs and to the development of newer agents with different specificities.