Drugs involved in self-poisoning: verification by toxicological analysis

During a two-month prospective survey in a metropolitan teaching hospital's accident and emergency department, 239 consecutive drug-related attendances (excluding admissions to hospital that were primarily alcohol related) were identified. This represented 2.6% of total attendances. Of the 199 patients who presented to hospital with self-poisoning, a biological specimen was obtained from 158 (79%) for toxicological analysis, thus providing reliable data on the drugs that were involved in the overdoses. The most common drug groups that were identified were barbiturate (51% of cases) and benzodiazepine (49%) agents, alcohol with other drugs (44%), cannabinoids (32%) and opiate analgesic drugs (25%). Quinalbarbitone and amylobarbitone (Tuinal) and oxazepam were the most common "single" preparations. The use of cannabis and alcohol and the use of several drugs concurrently were more common than in previously reported surveys of self-poisoning. Discrepancies between the purported drug consumption and the toxicological results were frequent; complete agreement occurred in only 35% of the cases. The TOXI-LAB system was an adequate method for toxicological analysis. However, for epidemiological studies an additional back-up method is recommended to verify the presence of some drugs such as barbiturate and benzodiazepine agents.