Poisoning with tricyclic and related antidepressants--a ten-year review.

Self-poisoning with tricyclic and related anti-depressant drugs has increased in frequency over the last few years so that, at present, some 20 per cent of patients admitted to hospital following self-poisoning have ingested a drug of this group, either alone or, more commonly, in association with alcohol, a benzodiazepine and/or other drugs. We present the results of a retrospective analysis of 316 admissions to a general medical hospital dealing with patients over 12 years, following self-poisoning with tricylic or related drugs. Although serious toxic effects may sometimes occur, their frequency has probably been over-estimated, at least in older children and adults; in this series the incidence of significant hypotension was 13 per cent, grand mal convulsions 4 per cent, respiratory depression to the degree of requiring mechanical ventilation 2 per cent and severe cardiac arrhythmias or conduction disturbances 1.5 per cent. It is suggested that routine 'prophylactic' treatment against convulsions and cardiac arrhythmias, advocated by some previous authors, is unnecessary and potentially dangerous; indeed, even the establishment of an intravenous infusion may put an extra strain on a depressed myocardium. In this series, supportive treatment alone was sufficient for the majority of patients (81.6 per cent) and additional treatment was given only in the presence of some specific indication. Using such conservative measures, the mortality rate in the 10-year study was only 0.6 per cent. Medical efforts in the future, it is suggested, would be more appropriately directed towards preventing unnecessary prescribing of these drugs for trivial mental upset, rather than the development of new drugs of this type or other 'prophylactic' measures, designed to prevent relatively rare toxic effects.