Recent Experience with Vasodilator Drugs
Because of these unfavorable results with hydralazine, recent investigators have turned to the use of calcium channel blocking drugs for the treatment of patients with primary pulmonary hypertension. Because calcium may play an important role in the pathogenesis of pulmonary hypertensive disorders and because calcium channel antagonists produce favorable effects in experimentally induced pulmonary hypertension, it was logical to apply nifedipine, verapamil, and diltiazem to the treatment of primary pulmonary hypertension in man. The primary hope with the use of these agents was that selective pulmonary vasodilation could be achieved without marked systemic vasodilator effects. Early clinical experience confirmed that nifedipine lowered pulmonary vascular resistance and pulmonary artery pressures at rest and during exercise, during short- and long-term treatment, and these effects were accompanied by symptomatic improvement.