[The bronchodilator effect of aerosol beta-2-mimetic and anticholinergic agents in patients with chronic bronchitis]

The aim of this study was to compare the effects of beta-2 stimulant adrenergic bronchodilators, salbutamol (S) and atropinic bronchodilators, oxitropium bromide (O). The drugs were administered by aerosol, alone or in combination. 20 patients with stable chronic bronchitis were randomised into two groups G1 and G2 and respiratory function tests were done on each group in two sequences, S1 and S2 with 24 hours between. The sequence S1 consisted of three spirometric measurements; an initial control measurement (C) preceding the inhalation of two puffs of 100 mcg of S with a repeat spirometry 15 minutes later followed by the inhalation of two puffs of 100 mcg of O followed by a final spirometry 45 minutes later, one hour after beginning the test. The protocol S2 was similar but the order of drugs was reversed (O then S). The subjects were subjected successively to regimes S1 and S2 for group 1 and inversely for group 2 according to the standard procedure for a crossover trial. The forced expired volume (FEV1) was expected as a percentage of the predicted values and absolute values. Thus only the first dose of inhaled bronchodilator increased slightly but significantly the FEV1. In effect, the administration of the second product led to no supplementary bronchodilator effect. The patients were classified as responders or non-responders for different thresholds of improvement of FEV1 of 10, 15 and 20%. The number of non-responders to the 2 classes of drugs was much greater when the threshold of improvement was raised to 20%. Some patients responded to bronchodilators, others uniquely to one of the two products and finally some to neither. Without reversibility tests it is not possible to predict the response to atropine from the response to beta-2-mimetics.