Single-dose comparison of salbutamol and Duovent-Berodual in asthma

Duovent-Berodual was compared with salbutamol from metered aerosols, in subjects with asthma, in a double-blind, randomised, placebo-controlled cross-over study. 10 stable asthmatics, 9 females and 1 male, all on regular inhaled bronchodilators and steroid treatment, were studied following prior assessment of reversibility. This was confirmed by at least a 15% improvement in forced expiratory volume in 1s (FEV1) following 200 micrograms of inhaled salbutamol. Inhaled bronchodilator therapy and oral theophyllines (4 subjects) were withheld for 8 and 48 h prior to investigation. Baseline FEV1 for each study day varied by less than 15%. Duovent-Berodual produced a greater improvement in mean FEV1 and mean peak expiratory flow rate (PEFR) compared with salbutamol at all time points. This was significant (p less than 0.05) for FEV1 at 120, 180, 210 and 240 min post-treatment. For PEFR a significant difference in response (p less than 0.05) was achieved at 90, 120, 150 and 210 min post-treatment. No significant difference was demonstrated for forced vital capacity (FVC) between the two active treatments at any time point. Ipratropium has been shown to improve FVC disproportionately to FEV1 and this has been attributed to dilatation of small airways. Seven subjects in this study described their asthma as lifelong. The failure to demonstrate significant differences in FVC response may reflect damage to small airways that render them unresponsive to ipratropium. This study demonstrates that Duovent-Berodual provides a significant improvement in bronchodilatation extending through to 4 h when compared with salbutamol.