Tricyclic antidepressant overdose

Abstract

Overdose from tricyclic antidepressants (TCAs) is increasing. TCAs are well absorbed orally, highly protein bound, and highly lipid soluble. Clinical features of poisoning with TCAs occur within 12 hours of ingestion, usually after a dose of 20 mg/kg or more. Clinical symptomatology involves various anticholinergic, central nervous system, and cardiovascular effects. Cardiovascular toxicity accounts for the majority of the fatalities and may include a hyperdynamic response, various arrhythmias and heart blocks, or severe hypotension. Prolongation of the QRS interval of 10 msec or more implies severe toxicity. Many factors limit the usefulness of drug levels in the overdosed patient. Treatment revolves around good supportive care and general poisoning management. The physician should no longer use physostigmine precipitously. Sodium bicarbonate is effective in treating many of the cardiovascular complications. Other cardiac drugs are used but with varying efficacy. Patients with significant signs or symptoms of toxicity require monitored hospitalization until clinically free of manifestations for 24 to 48 hours.