Effect of almitrine bismesylate on pulmonary vasoreactivity to hypoxia in chronic obstructive pulmonary disease.

The aim of this double-blind, placebo-controlled study was to determine whether acute administration of almitrine enhances hypoxic pulmonary vasoconstriction in patients with chronic obstructive pulmonary disease (COPD). Haemodynamics and blood gases were studied at various inspiratory fractional concentrations of oxygen (FIO2): 0.15, 0.21, 0.30 and 1.0, randomly administered for 20 min periods under constant infusion of either placebo or almitrine (8 micrograms.kg-1.min-1) in 20 patients with COPD. The almitrine group exhibited a significant increase in mean pulmonary artery pressure, pulmonary vascular resistance and arterial oxygen tension (PaO2) at FIO2 0.15, 0.21 and 0.30. During hypoxia, the increase in mean pulmonary pressure and pulmonary vascular resistance was three times greater in the almitrine group than the placebo group. No significant difference in cardiac output and systemic haemodynamics was found. These results suggest that almitrine at the dose used, enhances pulmonary vasoconstriction in COPD patients.