Beta-adrenoceptor blocking drugs: adverse reactions and drug interactions.

Beta adrenoceptor blocking drugs are relatively well tolerated and adverse reactions to them are not common. The ones that do occur are reviewed in this paper under the following headings: Short term adverse reactions, drug interactions, long term adverse reactions, risks in pregnancy and hazards of abrupt withdrawal. Predictable short term effects may be caused either by the actions of these drugs on the beta 1- or beta 2-receptors. The beta 1 adverse effects are hypotension, bradycardia and cardiac failure; these are best avoided by not giving beta-adrenoceptor blocking drugs to susceptible patients with cardiac disease. The beta 2 adverse effects on the bronchi, the peripheral arteries and various metabolic functions may be reduced to some extent by using a relatively cardioselective drug. Unpredictable short term effects such as fatigue, sexual dysfunction and gastrointestinal symptoms may occur but are not common problems with this group of drugs. Similarly, serious drug interactions are infrequent. Under the heading of long term adverse effects the practolol problem and the risk of causing malignant disorders have been considered. There is no evidence that any of the currently available drugs will cause either a practolol syndrome or malignant disease in man. However, the need for careful appraisal by drug regulatory bodies and continued vigilance by all prescribers of beta-adrenoceptor blocking drugs remains. The possible adverse effects of treatment during pregnancy are also considered. It now appears that beta-adrenoceptor drugs can be used safely in pregnancy but since neonatal bradycardia and hypoglycemia may occur, care should be taken to look for these complications. A serious deterioration may occur when beta-adrenoceptor drugs, given to patients with significant ischemic heart disease, are suddenly stopped. This is a rare occurrence but prescribers should be aware of it.