Use of β-Blockers in COPD

β-adrenoceptor antagonists are highly effective drugs for the treatment of cardiovascular conditions such as heart failure and acute coronary syndrome, both of which commonly occur as comorbidities in COPD caused by tobacco smoking. β-blockers are underused in patients with COPD and concomitant heart failure because of concerns regarding bronchoconstriction from antagonism of airway β2-adrenoceptors.1 So called cardio-selective β-blockers (such as metoprolol and bisoprolol) exhibit preferential antagonism of β1 over β2 receptors, which may mitigate bronchoconstriction and other extrapulmonary β2 receptor-mediated adverse effects (such as peripheral vasoconstriction, hyperglycemia, and hyperlipidemia), that occur with nonselective antagonists (such as carvedilol). Bisoprolol exhibits a higher degree of β1:β2 selectivity than metoprolol with relative ratios of 13.3 and 2.3, such that metoprolol confers a greater degree of dose-related β2-adrenoceptor blockade.2 However, β1-selective antagonists may also, in theory, confer less effective cardio-protection than nonselective drugs such as carvedilol because up to 40% of cardiac receptors are of the β2-subtype. Several lines of evidence support the relative safety of bisoprolol use in people with COPD.