The reduction of transmembraneous
calcium influx into vascular smooth muscle cells by
calcium antagonists leads to a reduction of tension development and vascular tone.
Calcium antagonists reduce forearm vascular resistance dose dependently and this effect can be successfully utilized for the treatment of
essential hypertension where they act by reducing increased peripheral vascular resistance thereby normalizing the main haemodynamic derangement of hypertensive patients. In contrast to other direct acting
vasodilators the
antihypertensive effect is not accompanied by sympathetic reflex activation or volume retention making it feasible to use
calcium antagonists as monotherapy for hypertensive patients. In view of the well documented efficacy, tolerability and an excellent safety profile
calcium antagonists have become drugs of choice for treatment of
hypertension in many patients. Although all
calcium antagonists have been shown to lower blood pressure they differ with respect to their vasodilating potency and their negative inotropic effects. The development of
dihydropyridine calcium antagonists which are potent arterial
vasodilators but have little if any negative inotropic effects at clinically used dosages further improves the safety profile of
calcium antagonists, particularly when used in hypertensive patients with impaired left ventricular function.