[Drugs combined with neuroleptics in anesthesia]

The neuroleptics are characterised by the large number of pharmacological effects they develop. When they are associated with other substances, it is frequent for the latter to have with neuroleptics one or several common sites of action. At this level, they develop phenomena of drug interaction, for example, synergy with depressors of the central nervous system or, in the periphery, with alpha-adrenolytic or parasympatholytic drugs. This type of interaction is used in anesthesia to obtain more intense effects with lesser doses of each component and also avoid the toxic effects of efficacious doses of general anesthetics used alone. However, although certain interactions are useful, others may prove harmful. This is in particular the case where neuroleptic drugs are administered after ingestion of alcohol. Various mechanisms, central and peripheral, explain the marked depression of the central nervous system which results. Potentialisation of the effects of tricyclic antidepressor drugs by neuroleptics raises a difficult problem for the anesthetist, the elimination of tricyclic antidepressor drugs is slow and requires several weeks after stopping treatment. During this period, the tissue and plasma concentrations become reduced gradually. They are pharmacologically insufficient, but are potentialised by injection of neuroleptic drugs, and may become active again, and even toxic. It seems to us advisable to avoid the use of neuroleptic drugs in patients treated with tricyclic antidepressor drugs and, if necessary, to use another method of anesthesia.