High dose titration of calcium channel blocking agents for primary pulmonary hypertension: Guidelines for short-term drug testing

Forty-seven patients with primary pulmonary hypertension were evaluated with a dose titration protocol utilizing nifedipine (20 mg orally) or diltiazem (60 mg orally) given every hour until maximal effectiveness was achieved. Of the patients tested, 15 (32%) had a >20% reduction in pulmonary artery pressure (mean 36.2 ± 8%, p < 0.01) and pulmonary vascular resistance (mean 50.2 ± 7%, p < 0.01) (pressure responders). Nineteen (40%) had 4.2 ± 20% reduction in pulmonary vascular resistance (mean 25.2 ± 12%, p < 0.01), with less than a 20% decrease in pulmonary artery pressure (resistance responders). Ten had no significant change in pulmonary artery pressure or pulmonary vascular resistance (nonresponders), and three were unable to tolerate the calcium channel blocking agents. No hemodynamic profile allowed prediction of the type of response to these agents. No mortality or serious morbidity was associated with the drug testing.