Experimental and clinical experience with the calcium antagonist diltiazem in hypertension

The arterial vasodilator properties of the calcium antagonist diltiazem were investigated by measurement of changes in forearm blood flow during brachial artery infusions of eight dosages of diltiazem in eight patients with mild to moderate hypertension. Forearm blood flow increased and calculated forearm vascular resistance decreased dose dependently. Comparison with the vascular effects of verapamil did not show any difference between the two drugs, attesting to their powerful vasodilator action. The clinical efficacy and feasibility of diltiazem monotherapy was evaluated in 40 patients with mild to moderate essential hypertension who were treated with a retarded formulation of 90 mg of diltiazem twice daily over 8 weeks. A subgroup of 21 patients were treated with two tablets of 90 mg of diltiazem once daily in the morning over 2 weeks. Blood pressure was lowered significantly as a result of either mode of diltiazem administration. This effect was maintained during open long-term therapy over a mean of 11 months. Heart rate and body weight did not change. Thus, the vasodilator properties of diltiazem can be utilized for effective long-term treatment of hypertension. The possibility of once-daily administration may prove useful for long-term treatment of a generally asymptomatic disease such as hypertension.