Beneficial effects of almitrine bismesylate on pulmonary gas exchange in COPD

Almitrine bismesylate 100 mg orally was given to eight patients with severe chronic obstructive pulmonary disease (COPD). In five patients, gasometric, haemodynamic and lung mechanics parameters, and almitrine plasma levels were measured at baseline and every hour up to five hours after almitrine bismesylate intake. Maximal almitrine plasma levels were reached after 2 hours (89 +/- 41 ng/ml, mean +/- SEM) and persisted up to the fifth hour (68 +/- 25 ng/ml). Pulmonary vascular resistance increased significantly from baseline 433 +/- 120 dynes.s.cm-5 to 503 +/- 124, p less than 0.05 at the second hour and to 509 +/- 119, p less than 0.05 at the fifth hour. Arterial oxygen saturation increased significantly from baseline 81.7 +/- 4.9% to 84.5 +/- 5.0, p less than 0.05 at the second hour and to 84.5 +/- 4.6, p less than 0.05 at the fifth hour. Venous admixture decreased significantly from baseline 35 +/- 9% to 30 +/- 9, p less than 0.05 at the second hour and to 28 +/- 9, p less than 0.01 at the fifth hour. Pulmonary artery mean pressure, cardiac output and minute ventilation did not change. The continuous distributions of ventilation-perfusion ratios (VA/Q), using the multiple inert gas elimination technique, were determined in six patients, at baseline and two hours after almitrine bismesylate intake. An improvement in VA/Q matching was observed after almitrine with a diversion of an average of 15 per cent of total blood flow from hypoxic units (VA/Q between 0.08 and 0.4) to normoxic units (VA/Q between 0.5 and 1.8).(ABSTRACT TRUNCATED AT 250 WORDS)