A Case Report of Chronic Doxepin Toxicity

• Published in: Clinical toxicology (Philadelphia, Pa.) Pa.), 2007-05, Vol.45 (4), p.365-365
• Main Authors: Gilmore, W S, Nelson, L S, Halcomb, SE
• Format: Article
• Language: English
• ISSN: 1556-3650

Objective: There is very little literature regarding chronic tricyclic antidepressant toxicity. We report a case of chronic doxepin toxicity with an absence of electrocardiographic manifestations. Case Report: A 58-year-old recovering alcoholic man with past medical history of hypertension, prostate cancer, bleeding cerebral aneurysm, gunshot to the chest, and depression presented to the local Veteran's Administration hospital complaining of drowsiness of several hours duration. During this admission, he had an extensive neurologic examination which included a head CT and EEG. The patient's hospital stay was uneventful and no specific neurological cause could be elicited for his symptoms. Two days after discharge, the patient presented to the hospital again complaining of continued weakness and inability to walk. On initial examination, the patient had stable vital signs, but was found to be lethargic with slurred speech. He was also found to be alert and oriented to name and place, had difficulty following commands and a shuffling, unsteady gait. A noncontrast head CT was negative and a neurology consult was obtained. Once again, the head CT was interpreted as normal. Electroencephalography showed diffuse beta activity, suggestive of drug effect. The patient was admitted to the neurology service and was found to have a doxepin level of 523 ng/ml and a nordoxepin level of 323 ng/ml on serum drug screening. An electrocardiogram demonstrated a normal sinus rhythm at a rate of 80 bpm with QRS duration of 92 msec without rightward.deviation of the terminal 40 msec. The patient was advised to decrease the amount of doxepin from 50 mg at bedtime to 25 mg at bedtime and discharged. Three days after discharge, the patient presented again with continued complaint of weakness, lethargy, ataxia and confusion. Repeat levels of doxepin and nordoxepin were obtained with an elevation of his doxepin level to 745 ng/ml and nordoxepin level to 447 ng/ml. Repeat electrocardiography demonstrated normal sinus rhythm at a rate of 95 bpm with a QRS duration of 94 msec without rightward deviation. The patient was admitted to the medicine service on continuous telemetry and his doxepin was held. Over the next 4 days, his neurologic symptoms resolved with the exception of his intention tremor. Upon discharge, the patient's doxepin level was 209 ng/ml and nordoxepin level was 455 ng/ml. Conclusion: The patient's neurologic complaints were likely caused by chronic doxepin toxicity wi