A one year double blind follow-up of blood gas tensions and haemodynamics in almitrine bismesylate therapy

Almitrine bismesylate, a chemoreceptor agonist, improves blood gases in chronic obstructive lung disease (COLD). Some authors have observed an increase in pulmonary artery pressure (Ppa) after single doses of almitrine bismesylate (A). This led to the present one year double blind placebo (P) controlled study to assess haemodynamic effects of long-term oral treatment in COLD (1.5 mg/kg/day for one year), together with clinical benefit and blood gas improvement. Twenty moderately severe patients entered the study, fifteen of whom completed it (eight in group (A), seven in group (P]. Blood gas values, minute ventilation (VE), mean pulmonary artery pressure (Ppa) and cardiac output (Qc) were periodically measured. Ppa and Qc remained unchanged in both groups throughout the study. We observed relevant clinical improvement without side effects and no significant increase in VE in group (A). Arterial oxygen tension (PaO2) showed a 1.2 kPa (9 mmHg) mean increase in group (A) and remained unchanged in group (P). These data and those from the literature seem to indicate that almitrine induces a vascular effect, especially after a single dose. However, as long as PaO2 improves simultaneously no long-term haemodynamic consequence is apparent. The discrepancy between immediate and long-term vascular effects of almitrine might be explained by the improvement in gas exchange which could reduce and/or counter-balance the vasoactive response. In conclusion, after one year of therapy almitrine bismesylate results in considerable clinical and blood gas improvements without significant haemodynamic change.