Almitrine bismesylate: a long-term placebo-controlled double-blind study in COAD--Vectarion International Multicentre Study Group.

701 patients, age 61.9 +/- 8.3 yr (mean +/- SD), with hypoxaemic chronic obstructive airways disease (COAD) were entered into a one yr placebo-controlled double-blind study to determine the effect of oral almitrine bismesylate on arterial blood gas tensions and clinical condition. Initial arterial O2 tension (PaO2) was 7.6 +/- 0.8 kPa (57.0 +/- 6.2 mmHg) and arterial CO2 tension (PaCO2) was 6.0 +/- 0.9 kPa (45.2 +/- 6.7 mmHg). Forced expiratory volume in one second (FEV1) was 0.87 +/- 0.35 l and forced vital capacity (FVC) was 2.31 +/- 0.72 l. 163 patients, evenly distributed between treated and untreated groups, were receiving long-term O2 therapy; other conventional therapy was continued. In a stabilization period before treatment, excellent reproducibility of blood gas tensions and spirometry was achieved. In the placebo group (P; n = 357), little change in physiological measurements or clinical assessment was recorded, 90 patients (25%) were lost from the study, mostly due to deterioration of their respiratory disease or to death; 3.4% withdrew for adverse reactions. The almitrine group (A; n = 344), received 100-200 mg per day orally in two divided doses, depending on the improvement in PaO2 achieved. On entry to the study their blood gas tensions, lung function tests, clinical assessment, history of hospitalization and frequency of right heart failure were not significantly different from the placebo group. After one yr of treatment, PaO2 rose from 7.6 +/- 0.8 kPa (57.4 +/- 6.1 mmHg) to 8.5 +/- 1.3 kPa (63.7 +/- 9.7 mmHg), p less than 0.001 compared with the placebo group. Red cell count decreased p less than 0.001 compared with the placebo group and FEV1 increased from 0.92 l to 0.95 l, p less than 0.001 compared with the placebo group. Dyspnoea, assessed on a 100 mm analog scale was unchanged in the almitrine group as a whole, but some individual patients withdrew on account of breathlessness. A smaller proportion of patients in group A were hospitalized and had episodes of right heart failure during the study than in group P (p less than 0.05). Vital signs, biochemistry and ECG characteristics did not change. 139 patients (40%) in this group did not complete the study, 35 (10%) through deterioration of respiratory symptoms or death (4.9%); 43 (12.5%) withdrew because of adverse reactions, either drug-related or not. The most frequent adverse reactions were gastro-intestinal, central nervous system disturbances, increased dyspnoea and peripheral paraesthesiae.(ABSTRACT TRUNCATED AT 400 WORDS)