ADVERSE REACTIONS WITH BETA-ADRENOCEPTOR BLOCKING-DRUGS - AN UPDATE

Beta-Adrenoceptor blocking drugs are widely used throughout the world, and serious adverse reactions are relatively uncommon. Many of those that do occur, including bronchospasm and peripheral ischaemia, are due primarily to blockade Of beta2-adrenoceptors. Recently developed beta-blockers with enhanced beta1-selectivity and partial beta2-agonist activity appear, in general, to have lesser effects upon airways function and vascular resistance, but none are regarded as being entirely 'safe' in patients with asthma. In the treatment of hypertensive patients with co-existing airways disease there are now effective alternatives to the beta-blockers, including calcium antagonists, alpha-adrenoceptor antagonists and angiotensin converting enzyme (ACE) inhibitors. However, in the presence of ischaemic heart disease, beta-blockers have specific advantages and may still be considered necessary in patients with airways disease. In this situation, agents with beta2-agonist activity are preferable to 'conventional' beta-blockers. However, there is still some risk that bronchospasm may occur in certain individuals, and the bronchodilator response to inhaled beta2-agonists might be impaired. In patients with peripheral vascular disease, beta-blockers with beta2-agonist activity are less likely to worsen the symptoms and signs of peripheral ischaemia, and may reduce the prevalence of peripheral coldness, a common adverse effect of beta-blockers. There is concern that beta-blockers may have significant central effects, including impairment of memory and concentration, although these are difficult to quantify. A number of pharmacologically unpredictable adverse reactions may occur rarely, including skin reactions, alopecia and arthropathy.