Effects of therapeutic doses of salbutamol alone and combined with beclomethasone dipropionate on airway responsiveness and cyclic AMP plasma levels in asthmatic patients

Twelve asthmatic patients received by inhalation for 2 weeks, in a double-blind, cross-over design, beclomethasone dipropionate (BDP; 600 micrograms/day) plus salbutamol (S; 900 micrograms/day), or S (900 micrograms/day) alone. Before and after each treatment course the subjects received intravenous cumulative doses of S up to 200 micrograms. In basal conditions and immediately before the next dose forced expiratory volume in 1 s (FEV1) and plasma cyclic AMP (cAMP) were measured. BDP+S treatment increased FEV1 basal values (p < 0.05) whereas inhaled S resulted in unsignificant improvement of ventilatory parameters. The slopes of the dose-response curves of FEV1 and plasma cAMP to intravenous S were unaffected by the two treatment courses. Our results suggest that DBP+S, differently from S alone, improves ventilatory function in asthmatic patients and that neither S nor S+BDP seem to affect adrenergic function.