Tricyclics--the most common agent used in potentially lethal overdoses.

Fifty-three cases of drug overdose requiring admission to a medical intensive care unit were studied. Tricyclic antidepressants were used in nearly 50 per cent of these serious adult overdoses. Barbiturates were involved in only 20 per cent. This may reflect changing patterns of drug usage and emphasizes the potential danger of tricyclics, the use of which is widespread in the general medical community. Unintentional overdoses occurred most often in substance abusers, whereas intentional overdoses occurred in a wider range of psychiatric disorders. A quarter of drug overdoses were free of psychiatric disease. Patients found to have an obvious manipulative intent were as likely to have made medically serious attempts as those who did not.