POTENTIAL HAZARDS OF PSYCHOACTIVE DRUGS IN ASSOCIATION WITH ANAESTHESIA

Abstract

In recent years psychoactive ( antidepressant) drulgs have been found useful in the treatment of both psychotic and psychoneurotic depression The use of these drugs appears to be increasing, for they have been advocated in the treatment of angina pectoris, hypertension, and rheumatoid arthritis as well Thus, not only the psychotic patient on these drugs receiving thiopentone and succinylcholine for E C T presents to the anaesthetist, but also a wide variety of surgical patients may have been exposed to these drugs Pharmacologically, the antidepressants may be classified into two main groups (1) compounds which inhibit the enzyme monoamine-oxidase (2) compounds which donot inhibit the enzyme monoamine-oxidase The majority of the psychoanaleptics in current use are monoamine-oxidase inhibitors By virtue of their ability to inhibit monoamine-oxidase, there are increased levels of brain serotonin and/or norepinephrine, with resultant psychoactive effects But the concentration of these biologically active amines not only appears to be increased at central sites but may also be elevated at peripheral autonomic synaptic and effector areas, providing a hazardous setting for subsequently administered anaesthetics Four representative patients illustrate that hypotension, hypertensive crises, hyperthermia, convulsions, coma, and potentiation of atropine, corticosteroids, and Arfonad have all been observed as untoward reactions when anaesthesia oi anaesthetic agents are given to patients on psycho-active drugs Management of these reactions is primarily supportive Caution must be used in the administration of vasopressors (norepmephrine) or adrenergic blockers (phentolamine) in the treatment of hypotensive or hypertensive reactions, respectively Avoidance of these reactions is desirable Therefore a high index of awareness of the hazards that these drugs present in association with anaesthesia and care to ascertain whether the patient is or has been taking these drugs during the 21 days prior to anaesthesia seem imperative