title: Adverse reactions to beta 2-agonist bronchodilators.
abstract: Beta 2-Agonists are safe and effective bronchodilator drugs. Their major adverse effects of skeletal muscle tremor, tachycardia and various metabolic effects are mediated by beta-adrenoceptor stimulation and are reversible. Skeletal muscle tremor is the most frequent dose-limiting side effect. It may be reduced by commencing treatment with a low dose and if it persists another beta 2-agonist may be tried. Other side effects such as cardiac arrhythmias and reduction in PaO2 are a serious potential problem in some susceptible asthmatics. However, they are infrequent or of a mild degree and are generally outweighed by the good control of asthma produced by beta 2-agonists. Side effects from beta 2-agonist therapy can be minimised by use of the inhaled route which selectively delivers the drug to the airways. Furthermore, selective tolerance develops to their side effects. The dose of a beta 2-agonist should be assessed on the basis of therapeutic effect and the level of tolerance to its side effects. Recommended doses of beta 2-agonists used for long term therapy do not cause clinically significant desensitisation of airway beta-adrenoceptors, although this may become a relevant problem in patients who are regularly receiving very high doses. Intravenous beta 2-agonists have a place in the treatment of severe asthma not responding to nebuliser therapy. In this life-threatening situation with severe airflow obstruction, monitoring of heart rate, PaO2, plasma potassium and the electrocardiogram should be mandatory and supplemental oxygen given so that serious adverse effects are presented.
mesh_terms: D000318:Adrenergic beta-Agonists / Q000009:adverse effects*; D001993:Bronchodilator Agents / Q000009:adverse effects*; D005260:Female; D006801:Humans; D011247:Pregnancy
chemical_list: D000318:Adrenergic beta-Agonists; D001993:Bronchodilator Agents