Beta-blockers: friend or foe in asthma?

Background and aim: Recently, β-blockers have been suggested as a potential maintenance treatment option for asthma. The aim of this review is to provide an overview of the current knowledge of the potential benefits and risks of β-blocker therapy for asthma. Method: Systematic literature review. Results: No significant increase in the number of patients requiring rescue oral corticosteroid for an exacerbation of asthma has been observed after initiation of β-blocker treatment. Patients with mild to moderate reactive airway disease, probably both asthma and chronic obstructive pulmonary disease, may have a limited fall in forced expiratory volume in 1 second (FEV₁) following single-dose administration of β-blocker, whereas no change in FEV₁ has been reported following long-term administration. In a murine model of asthma, long-term administration of β-blockers resulted in a decrease in airway hyperresponsiveness, suggesting an anti-inflammatory effect. In keeping with this, long-term administration of a nonselective β-blocker to steroid-naïve asthma patients has shown a dose-dependent improvement in airway hyperresponsiveness, and either an asymptomatic fall in FEV₁ or no significant change in FEV₁. Furthermore, available studies show that bronchoconstriction induced by inhaled methacholine is reversed by salbutamol in patients on regular therapy with a β-blocker. On the other hand, a recent placebo-controlled trial of propranolol and tiotropium bromide added to inhaled corticosteroids revealed no effect on airway hyperresponsiveness and a small, not statistically significant, fall in FEV₁ in patients classified as having mild to moderate asthma. Conclusion: The available, although limited, evidence suggests that a dose-escalating model of β-blocker therapy to patients with asthma is well tolerated, does not induce acute bronchoconstriction, and, not least, may have beneficial effects on airway inflammation and airway hyperresponsiveness in some patients with asthma. Further studies addressing the potential role of β-blocker therapy for asthma are clearly needed, but careful selection of the target population is warranted [ABSTRACT FROM AUTHOR]