Increased respiratory chemosensitivity induced by oral almitrine in healthy man

Cardiorespiratory effects of 50 mg and 100 mg doses of almitrine and placebo given orally on separate test days to twelve healthy volunteers were assessed in a double-blind crossover study. The drug caused no significant changes in ventilation, mixed venous CO2 tension, metabolic rate, heart rate or blood pressure while they were resting and breathing room air. With progressive hypercapnia, however, the ventilatory response increased by 5% after the 50 mg dose (NS) and by 27% after the 100 mg dose (P less than 0.05). There were greater increases in the response to progressive hypoxia by 78% after 50 mg of almitrine (P less than 0.01) and by 120% after 100 mg (P less than 0.01), which was also significantly greater than the increase after the 50 mg dose (P less than 0.01). In contrast there were only minor and inconsistent changes in chemosensitivity after administering placebo. The findings are consistent with an agonist action of almitrine in the peripheral chemoreceptors and suggest that it may have clinical value in managing respiratory failure due to hypoventilation.