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About beta-blockers
Beta-blockers are used as treatment for hypertension, angina, myocardial infarction, cardiac arrhythmias and heart failure, and as prophylaxis against cardiovascular events after high-risk surgery. 8 - 12
First-generation beta-blockers (e.g. propranolol, sotalol, timolol) are non-selective, in that they block both beta1 receptors (mainly in the heart) and beta2 receptors (mainly in the lungs). Blockade of beta1 receptors inhibits the sinus and atrioventricular nodes and reduces myocardial contractility, reducing myocardial oxygen demand and the likelihood of tachyarrhythmias. 13 However, blockade of beta2 receptors in airway smooth muscle can lead to bronchospasm, so beta-blockers have been widely seen as contraindicated in patients with airways disease, a caution that is reflected in the drugs' summaries of product characteristics. 14 Second-generation beta-blockers (e.g. atenolol, bisoprolol, celiprolol, metoprolol) are selective in that they act mainly on beta1 receptors, so their cardiac effects predominate. At high doses, however, their effect on beta2 receptors may also become significant. Cardio-selectivity varies between drugs, with bisoprolol being the most selective for beta1 receptors among the beta-blockers in common use. Third-generation beta-blockers have additional vasodilator properties and may be cardio-selective (e.g. nebivolol) or non-selective (e.g. carvedilol), or have intrinsic sympathomimetic activity (e.g. oxprenolol, pindolol); however, the clinical relevance of these additional properties is uncertain.
About COPD
COPD is an inflammatory disease with systemic effects, and is usually progressive. 15 16 It is primarily caused by chronic exposure to tobacco smoke, but can also be due to exposure to occupational dusts or chemicals, or smoke from cooking and heating fuels, factors that damage airways and lung tissue. 15 16 The diagnosis of airflow obstruction is confirmed by spirometry that shows a post-bronchodilator FEV1/FVC ratio below 0.7 (where FEV1 is the forced expiratory volume in 1 second and FVC is the forced vital capacity). 16 Spirometry can also describe the severity of airflow obstruction, with thresholds for defining mild, moderate and severe obstruction set at 80%, 50% and 30% of expected values, respectively; however, the clinical manifestations of COPD are highly variable. 2 16
The aims of management in COPD are to relieve symptoms, treat and prevent exacerbations, improve quality of life and prolong survival. A multidisciplinary approach should be adopted, incorporating smoking cessation, drug treatment (which may include bronchodilators and inhaled corticosteroids), immunisations,...