Calcium Antagonistic Agent

Hemodynamic monitoring after a single dose (10 mg) of nifedipine in 27 primary hypertensive subjects (diastolic pressure > 110 mm Hg) documented that this calcium antagonistic agent exerts a potent arteriolar vasodilating action, which results in prompt (-21% of control at 30 minutes) and persistent (-16% of control at 120 minutes) fall in mean arterial pressure associated with a rise in cardiac output and pulse rate. The same patients received oral treatment for 3 weeks. Hourly pressure readings showed that 1) the antihypertensive response to each dose lasts 8-12 hours; and 2) nifedipine every 6 hours significantly reduced blood pressure throughout the 24 hours, without postural hypotension. Side effects were short-lasting (headache in five patients, palpitation without arrhythmias in eight patients, burning sensation in the face and legs in five patients and sporadic extrasystoles in five patients) and tended to disappear with continued treatment. Development of drug resistance, sodium retention, plasma volume expansion, renin release or angina pectoris were not observed during the study. Although these findings seem to differentiate nifedipine from other vasodilators currently used in the treatment of hypertension, broader experience and more prolonged trials with nifedipine as an antihypertensive agent will be needed before conclusions can be drawn on these particular aspects.