The impact of regular bisoprolol on the response to salbutamol in asthma: A double-blind randomized placebo-controlled crossover trial

Background and objective Non-selective beta-blockers impair the bronchodilator response to beta(2)-agonists. Cardio-selective beta(1)-blockers are less likely to cause this effect, yet they remain relatively contraindicated in asthma. We investigated whether the response to salbutamol is impaired during cardio-selective beta(1)-blocker treatment in people with asthma. Methods A random-order, double-blind, placebo-controlled, non-inferiority, crossover study was conducted comparing up to 5 mg bisoprolol daily for 2 weeks with matching placebo, with an open-label extension of up to 10 mg bisoprolol daily. After each treatment period, mannitol was inhaled to induce bronchoconstriction with a 15% fall in forced expiratory volume in 1 s (FEV1). Immediately after mannitol challenge, salbutamol (100, 100 and 200 mu g) was administered via spacer at 5-min intervals with repeated FEV(1)measures. The FEV(1)recovery with salbutamol was measured as an area under recovery curve (AUC). Based on earlier research, a clinically relevant non-inferiority limit of a 30% reduction in the AUC was set. Results A total of 19 adults with mild asthma and positive inhaled mannitol challenge completed the study. Adjusting for the FEV(1)fall induced by mannitol and treatment sequence, the mean AUC response to salbutamol after bisoprolol was 5% lower than after placebo, with a one-sided 95% confidence interval (CI) of 26% lower. Thirteen participants completed the open-label extension up to 10 mg bisoprolol daily with mean AUC 11% higher after bisoprolol with a 95% CI of 5% lower. Conclusion The bronchodilator response to rescue salbutamol after mannitol-induced bronchoconstriction is non-inferior during regular treatment with the cardio-selective beta(1)-blocker, bisoprolol, compared to placebo. Clinical Trial Registration:ACTRN12618000306213 at https://www.anzctr.org.au

Automated summary

The study investigated the impact of cardio-selective beta(1)-blocker bisoprolol on the response to salbutamol in patients with asthma. The results showed that there was no significant difference in the bronchodilator response to salbutamol after bronchoconstriction induced by mannitol between bisoprolol treatment and placebo.