A comparison of the drugs taken in fatal and nonfatal self-poisoning.

The objective of this study was a) to compare patterns of drug use in fatal and nonfatal overdoses and b) to find out if toxic drugs are overrepresented in overdoses with fatal outcome. A total of 179 cases of fatal overdoses in Switzerland (population 6.6 million) were compared with 269 medically treated self-poisoners from the agglomeration of Berne (population 301,630). Because of frequent multiple drug use, all the different compounds taken singly or in combination with other drugs were recorded and grouped according to drug types. The patterns of the frequencies of drugs used were remarkably similar in both groups. The majority of the drugs were psychotropics (81% in fatal and 68% in nonfatal overdose). Twenty-nine completed suicides were the result of drug combinations specifically recommended by EXIT. In the remaining cases benzodiazepines were used most frequently in both attempted and completed suicide, often in combination with other drugs or alcohol. Barbiturates were the only drugs recorded significantly more often in fatal overdoses (9% vs 3%). No significant difference was found for tricyclic antidepressants (13% vs 10%), or other types of drugs. The results are consistent with our assumption that drugs with higher toxicity would be overrepresented in overdoses with fatal outcome. Barbiturates, which are well known to be dangerous in overdose, were clearly associated with fatal overdoses, but not tricyclic antidepressants. This, in our view, suggests that the risk of prescribing tricyclic antidepressants should not be overestimated. The frequent use of benzodiazepines in completed suicide, however, indicates that there are no truly safe drugs in overdose.