Cross‐over study of the efficacy of four beta 2‐sympathomimetic bronchodilator aerosols

Abstract

1 Bronchodilator efficacy of four beta 2‐sympathomimetic aerosols, fenoterol, orciprenaline, salbutamol and terbutaline has been compared in nine patients with chronic stable reversible airways obstruction using a double‐blind placebo controlled cross‐over design. Two puffs of each agent were given on two separate occasions to each of the patients and the forced expiratory volume in one second (FEV1) and the vital capacity (VC) were measured before and 30, 90, 150 and 210 min after administration. 2 Multivariate analysis of the data at 30 min showed FEV1 and VC in these patients to be so highly correlated that they could be considered as a single variable. 3 When absolute change in VC at 30 min was used as the response criterion, efficacy of the four drugs was significantly better than placebo (P < 0.01). It was not possible to rank all four drugs in order of effectiveness; fenoterol and salbutamol were significantly better than terbutaline and orciprenaline (P < 0.01) but this was complicated by a significant interaction effect between drugs and patients (P < 0.01). 4 Similar results were obtained when absolute and relative changes in FEV1 and VC and area under the curve were used as response variables. 5 The study demonstrates that important individual differences in patient response may be concealed if only average drug effects are considered.

Classification of β‐adrenoceptors in human isolated bronchus

“…While these different central airways preparations have been of great value in the screening of potential bronchodilator amines, many of them do not accurately reflect human central airways with respect to the ,B-adrenoceptor subtypes that they contain. Evidence from studies in conscious man strongly suggests a predominance of 12-adrenoceptors in central airways (Larsson & Svedmyr, 1977;Madsen et al, 1979). However, 13i-adrenoceptors predominate in the trachea of the cat (Lulich, et al, 1976;O'Donnell & Wanstall, 1983), rabbit (Bristow etal., 1970;Toda etal., 1978) and pig (Goldie et al, 1983) while 32-adrenoceptors predominate in guinea-pig trachea (O'Donnell 1972;O'Donnell & Wanstall, 1979).…”