Cardioselective β-Blockers Generally Are Safe in Asthma Patients

β-blockers can cause airway obstruction and even severe exacerbations in asthma patients. The mechanism of action is presumed to be catecholamine antagonism at the pulmonary β₂-receptor with resulting unopposed cholinergic tone causing bronchoconstriction. However, a 2002 Cochrane review concluded that, in patients with mild-to-moderate asthma, cardioselective β-blockers did not confer substantial short-term respiratory effects and should not be withheld from asthma patients with heart disease (Cochrane Database Syst Rev 2002; 4:CD002992).

Researchers performed a meta-analysis (32 studies with 548 adult patients) to examine the effect of cardioselective and nonselective β-blockers on lung function and symptoms in patients treated for 1 to 7 days. In a dose-responsive manner, selective β-blockers caused a mean 7% absolute drop in forced expiratory volume in 1 second (FEV₁) and attenuated β-agonist response by a mean of 10%. One in 8 patients experienced decreases in FEV₁ of ≥20%, and 1 in 33 patients experienced worsened asthma symptoms. Nonselective β-blockers caused a mean 10% drop in FEV₁ and attenuated β-agonist response by 20%. One in 9 patients experienced absolute decreases in FEV₁ of ≥20%, and 1 in 13 patients had worsened asthma symptoms. Drug-specific differences were noted: celiprolol (not available in the U.S.) had the least effect; atenolol and metoprolol (selective agents) and labetalol and propranolol (nonselective agents) had sequentially greater effects.