Interactions between psychotropics, anaesthetics and electroconvulsive therapy: implications for drug choice and patient management.

Despite many predictions that electroconvulsive therapy (ECT) would be replaced by pharmacotherapy, ECT has remained an invaluable adjunct in the management of severe psychiatric disease. Both pharmacotherapy and ECT continue to be used extensively, and will frequently be administered concurrently. The majority of patients requiring ECT will need anaesthesia; therefore, interactions could conceivably occur between the psychotropic drugs, ECT and the anaesthetic agents utilised. In managing an anaesthetic for ECT the effects of the anaesthetic agents and other medications on seizure intensity are important determinants influencing outcome. With regard to the antidepressants, tricyclic antidepressants (TCAs) and ECT can be combined safely and beneficially. More care is required when ECT is administered in the setting of a monoamine oxidase inhibitor (MAOI), especially the older irreversible varieties and in patients recently placed on MAOI therapy. Of the anticonvulsants and mood stabilisers, lithium and ECT given concurrently add significant risk of delirium and/or organic syndromes developing. Possible concerns with valproate, carbamazepine, lamotrigine, gabapentin and topiramate are that they may inhibit seizure activity. Additionally, carbamazepine may prolong the action of suxamethonium (succinylcholine). The combination of antipsychotics and ECT is well tolerated, and may in fact be beneficial. As regards the anxiolytics, benzodiazepines have anticonvulsant properties that might interfere with the therapeutic efficacy of ECT. CNS stimulants on the other hand may prolong seizures as well as produce dysrhythmias and elevate blood pressure. Calcium channel antagonists should be used with great care to avoid significant cardiovascular depression. The anaesthesiologist should therefore remain vigilant at all times, as untoward responses during ECT might occur suddenly due to interactions between psychotropics, anaesthetic agents and/or ECT.