Think the impossible: β-blockers for treating asthma

Asthma was originally thought to be associated with an intrinsic defect in β₂ADR (β₂-adrenoceptor) function, tipping the balance towards parasympathetic bronchoconstriction. Hence β-blocking drugs (such as β₂ADR antagonists and inverse agonists) may cause acute bronchoconstriction which, in turn, may be attenuated by anti-cholinergic agents. Although β₂-agonists are highly effective for the acute relief of bronchoconstriction, their chronic use is accompanied by an adaptive reduction in β₂ADR numbers and associated desensitization of response, resulting in increased exacerbations and rare cases of death. The hypothesis examined in the present article is that, while single dosing with a β-blocker may cause acute bronchoconstriction, chronic dosing may afford putative beneficial effects including attenuated airway hyper-responsiveness.