NIFEDIPINE INHIBITS THE EFFECTS OF ALMITRINE IN PATIENTS SUFFERING FROM PULMONARY-ARTERY HYPERTENSION SECONDARY TO CHRONIC OBSTRUCTIVE PULMONARY-DISEASE

It has been suggested that almitrine improves the local ventilation/pe rfusion ratio by enhancing hypoxic pulmonary vasoconstriction (HVC), l eading to an increase in pulmonary vascular resistance (PVR) and PaO2. The goal of the present study was to determine if pulmonary vasodilat ion induced by nifedipine inhibits the enhancement of HVC (and consequ ently of PaO2), in patients suffering from chronic obstructive pulmona ry disease (COPD). Two groups of 10 patients were compared in a contro lled, double-blind study. Hemodynamics and blood gases were measured d uring continuous infusion of placebo or almitrine (8 mug/kg/min). Two hours after the onset of the infusion, a single dose of nifedipine (10 mg) was given sublingually. Almitrine infusion was followed by an inc rease in PaO2 (20%) and PVR (48%). In the almitrine group, after nifed ipine, the PVR decreased 33% and PaO2 dropped to baseline while in the placebo group the PVR decreased 22% and PaO2 fell to 11% below baseli ne. In COPD patients, nifedipine inhibits almitrine-induced pulmonary vasoconstriction.