Role of calcium antagonists in cardiovascular therapy.

Abstract

SUMMARYThe development of drugs which selectively block the "slow" channels by which calcium enters the cell (calcium antagonists) has provided valuable information about the role of transmembrane calcium exchange in man and has offered new therapeutic approaches. The principal effect on the cardiovascular system is relaxation of vascular smooth muscle but some of these drugs also have electrophysiological effects, especially slowing of conduction in the atrioventricular node; verapamil is the agent of choice in supraventricular tachycardia. Significant myocardial depression does not usually occur with doses used clinically. The calcium antagonists have specific value in variant angina. By causing peripheral vasodilatation they are also effective hypotensive agents and do not cause reflex tachycardia in chronic use. Their value in hypertrophic cardiomyopathy and in the protection of ischaemic myocardium remains to be proven.

Treatment of angina pectoris with nifedipine: importance of dose titration.

“…There is a medical school attached to the hospital, and for its use a library, museum, dissecting-room, and other necessary accommodation are provided; the weekly average of in-patients is said to be about 1800, the yearly 14,000, so that there are about 230 new patients admitted weekly. The death rate is 13 We announced last week that the authorities at the Horse Guards had decided that "easy riding" should henceforth be adopted in the British cavalry. While the spirit of reform is active, we hope our poor troop-horses will not be forgotten.…”

Effects of selective channel blocking agents on contractions and action potentials in K+‐depolarized guinea‐pig atria

“…Calcium entry blocking agents are a chemically heterogeneous group of compounds which offer potential therapeutic benefit in the treatment of cardiovascular disease (see Ellrodt et al, 1980;Dargie et al, 1981;Awan et al, 1982, for recent reviews). Although the pharmacological profiles and precise sites of action may differ, these compounds all share the ability to inhibit the influx of calcium ions which occurs during membrane depolarization.…”

Verapamil in Ventricular Tachycardia

“…It alters the kinetics of Ca++ and K+ transsarcolemmal fluxes [l, 2], depresses both A-V nodal and S-A nodal function, but does not affect His-Purkinje conduction [17,18], As recently reviewed by Amman et al [3] and by Dargie et al [4], it is commonly rec ommended for paroxysmal supraventricular and junctional tachyarrhythmias. The effect of verapamil on ventricular ectopic activity has not been thoroughly investigated, but it is currently considered an ineffective drug for ventricular arrhythmias [4,5]. However, there have been anecdotal reports describing an occasional beneficial effect.…”

“…Verapamil is a well-known slow channel blocking drug with several other 'accessory' effects such as delayed activation of the out ward K+ current, and at high concentration it also blocks the fast inward Na+ current and inhibits the muscarinic and alpha receptors [1,2], It has an excellent antiarrhythmic ef fect in supraventricular tachyarrhythmias [3,4], but has been considered ineffective for the treatment of ventricular arrhythmias [4. 5].…”