Calcium antagonists: an overview.

Abstract

Calcium antagonists reduce the influx of calcium ions through the calcium channels. This causes a reduction in myocardial contractility or a fall in vascular resistance because of a lowering of vascular smooth muscle tone. Therefore, the net effect is a fall in blood pressure. The three major classes of calcium antagonists, the dihydropyridines, papaverine derivatives, and benzothiazepines, differ in molecular structure and their binding characteristics to the calcium channels. Furthermore, newer antagonists, particularly the dihydropyridines such as nicardipine, have a high affinity for vascular tissue and are highly selective for vascular smooth muscle. These compounds also have a favorable effect on hypertension mainly because of lowering of vascular resistance. In addition, they do not cause potentially negative metabolic effects on glucose or lipid levels and are generally well tolerated. Based on these findings, the Joint National Committee in the United States and the World Health Organization/International Society of Hypertension Committee on the Management of Mild Hypertension recommended the use of calcium antagonists as first-line treatment in hypertension.