The toxicity of drugs used for suicide.

Death from suicidal drug overdose differs from other forms of suicide in that the drugs are often prescribed by the patient's physician. In 1987, 3 of the 12 most commonly taken drugs in completed suicide were antidepressants (dothiepin, amitriptyline and imipramine). Antidepressants account for approximately 15% of all drug overdoses. The differences in toxicity between antidepressants have been measured using fatal toxicity indices, which relate the number of deaths and the amount of drug prescribed. Results from the United Kingdom covering the years 1975 to 1986 have shown that older tricyclic antidepressants have a fatal toxicity index 5 to 8 times higher than that of new antidepressants such as mianserin. The limitation of barbiturate prescribing has been followed by a fall in deaths from these drugs. Hopefully in the future it might be possible either to prescribe less toxic antidepressants or to identify the patients at greatest risk of drug suicide and to prescribe for them the least toxic drugs.