Acute trazodone poisoning: clinical signs and plasma concentrations.

A total of 70 patients presenting with suspected acute trazodone poisoning were notified to the Poisons Unit (National Poisons Information Service for England) from August 1980 until March 1983. Detailed follow-up information was obtained on 41 patients, 22 of whom were thought to have ingested trazodone alone. In these latter patients drowsiness (11), ataxia (5), nausea/vomiting (4) and dry mouth (2) were the manifestations of toxicity reported most frequently, only 2 patients became unconscious (grade 2 or 3 coma), and all recovered uneventfully with no more than minimal supportive therapy. The presence of trazodone was confirmed in 8 out of 9 patients from whom specimens (blood and urine) were received. The highest plasma trazodone concentrations (15 and 19 mg/l, respectively) were both associated with only drowsiness and ataxia. However, in 2 further patients moderate plasma trazodone concentrations (4.2 and 8.2 mg/l, respectively) were associated with deep (grade 3-4) coma, although 1 of these latter patients had also ingested ethanol (plasma concentration 3.0 g/l). Although acute trazodone poisoning does not appear to be associated with cardiac arrhythmias or convulsions, these results emphasise that drowsiness and ataxia are commonly encountered, while coma may occur in severe cases. The possible contribution of metabolites of trazodone to toxicity and the potentiating effect of co-ingested drugs or alcohol must be remembered.