Serum nifedipine concentrations and response of patients with pulmonary hypertension.

In patients with primary pulmonary hypertension who respond to nifedipine during acute drug testing, there is a significant linear correlation of serum nifedipine concentration with pulmonary artery pressure and resistance. Although most demonstrate an initial response at readily attainable nifedipine concentrations with conventional dosages, a subset of patients seem to display delayed or incomplete oral absorption; these results may facilitate the clinical use of nifedipine in patients with primary pulmonary hypertension.