The problem of tricyclic antidepressant poisoning.

In the year May 1976 to April 1977, 489 enquiries about the management of tricyclic antidepressant poisoning received at the London Centre of the National Poisons Information Service were followed-up. One hundred and sixty-four patients (33.5%) were unconscious, convulsions occurred in 62 (12.7%), hypotension in 31 (6.3%), respiratory depression in 28 (5.7%), tachydysrhythmias in 17 (3.5%) and cardiac arrest in 12 patients (2.5%). Sixteen patients died (3.3%). No statistically significant differences were found between individual antidepressants although poisoning with amitriptyline-like drugs resulted in a significantly higher proportion of unconscious patients than poisoning with imipramine-like drugs (P less than 0.01). There were more asymptomatic children than adults and more unconscious adults than children. Tricyclic antidepressant poisoning is a major clinical problem in general medical and paediatric practice.