Cyclic Antidepressant Poisoning: A Review and Case Report

Although newer cyclic antidepressants have been introduced over the past several years, the tricyclic antidepressants (TCAs) continue to be the leading cause of morbidity from drug overdose in the United States. Overdose features depend on the particular cyclic antidepressant ingested and its pharmacological properties, and can include CNS depression, cardiac arrhythmias, hypotension, seizures, and anticholinergic symptomatology. Life-threatening symptomatology almost always begins within 2 hours, and certainly within 6 hours, after arrival to the emergency department. Plasma TCA levels are unreliable predictors of TCA toxicity and are not recommended. An ECG with a prolonged QRS complex more than 100 msec seems to be the best indicator of serious sequelae with TCAs. Management consists of stabilization of vital signs, gastrointestinal decontamination, intravenous sodium bicarbonate, and supportive care. Agents once thought to be useful for the treatment of cardiac dysrhythmias and seizures such as phenytoin and physostigmine should be avoided. The future of TCA antibody fragments in the treatment of TCA overdose seems promising. Newer and, to some degree, safer antidepressants in overdose have recently been introduced, and they include fluoxetine, trazodone, and sertraline. Amoxapine, bupropion, and maprotiline seem to be as toxic as the TCAs. A significant interaction between cyclic antidepressants and monoamine-oxidase inhibitors exists. Management includes supportive care and basic poison management. Prevention of poisoning seems to be the most logical and effective method of maintaining patient safety. TCAs should be avoided in children younger than 6 years old. All adults with suicidal ideations should receive no more than a 1-week supply (about 1 g) of drug. Finally consideration should be given to using one of the newer, safer antidepressants in all patients with suicidal ideations.