Similarities and differences in the antihypertensive effect of two calcium antagonist drugs, verapamil and nifedipine.

The short- and long-term effects of two calcium channel blocking drugs, verapamil and nifedipine, on blood pressure, heart rate, plasma catecholamines, plasma renin activity, plasma volume and cardiac performance (echocardiography) were studied in essential hypertensive patients and in normal subjects. Verapamil, 160 mg orally, reduced blood pressure within 60 minutes in 22 hypertensive patients, but not in 12 normotensive subjects. Nifedipine, 10 mg sublingually, reduced blood pressure within 15 minutes in 19 hypertensive patients, but not in 7 normotensive subjects. Plasma noradrenaline was significantly increased both in normal subjects and in hypertensive patients only after nifedipine was administered. Verapamil (80 mg three times a day) first, and nifedipine (10 mg three times a day) thereafter, or vice versa, were given to 12 hospitalized hypertensive patients on a fixed sodium and potassium intake; the drugs produced similar blood pressure reductions, but heart rate and plasma catecholamines were increased only after nifedipine (p less than 0.05). Neither drug affected plasma volume, aldosterone or plasma renin activity. Long-term ambulatory treatment with verapamil (80 or 160 mg three times a day for 2 to 4 months) or nifedipine (10 mg three times a day for 2 months) produced changes in all variables that were similar to those observed in the hospital (controlled) study. Shortening fraction was significantly increased after nifedipine (p less than 0.05) but no change was observed after verapamil. In conclusion, blood pressure is effectively reduced by both verapamil and nifedipine; an appreciable adrenergic stimulation may be caused by nifedipine, but usually not by verapamil, and fluid retention, renin release or myocardial depression is not observed during verapamil or nifedipine treatment.