Calcium antagonists in the treatment of hypertension. An overview.

The availability of calcium antagonists has provided yet another therapeutic option in the management of hypertension. Calcium antagonists lower the blood pressure in hypertensive individuals while preserving the blood flow at the microcirculatory level. While all the available calcium antagonists are effective in the treatment of hypertension, they differ in their hemodynamic and pharmacologic actions. Nifedipine appears to be suitable for immediate treatment of severe hypertension and for chronic treatment of uncomplicated or refractory hypertension. In some but not all patients, co-administration of a beta-blocker is necessary to blunt reflex tachycardia. This problem is less likely with the tablet/long-acting formulation of nifedipine. Verapamil and diltiazem are useful as initial therapy for chronic mild-to-moderate hypertension. They are as effective as other first-line drugs in the treatment of uncomplicated hypertension. The heart rate with verapamil or diltiazem does not change or is slightly reduced, thus contrasting with nifedipine. Experience to date suggests that calcium antagonists do not cause adverse biochemical effects and in this respect are superior to diuretics and certain beta-blockers. Currently, verapamil is available as a sustained release preparation. In the near future, nifedipine or diltiazem may also be available in the long acting formulation to permit simplicity and to enhance patient compliance in the treatment of hypertension.