Sustained-Release Bupropion Overdose: A Case Report

Bupropion is an atypical antidepressant with a unique aminoketone structure similar to amphetamines. A narrow therapeutic margin is evident from observational studies that show seizure activity with doses of 400-600 mg or higher.
A 38-year old woman took an overdose of 6 grams of bupropion with 110 grams of alcohol. She presented to the Emergency Department with agitation, visual hallucinations and myoclonus of the upper limbs; eyes spontaneously open with isochoric and light reactive pupils with horizontal nystagmus; afebrile, normotensive (121/63 mm Hg) and tachycardic (120 beats/minute). The electrocardiogram revealed a sinus tachycardia with prolonged QT interval (QT/QTc: 0.46/ 0.537) and a QRS complex length in the upper limit of normal. Arterial blood gases revealed metabolic acidosis (pH = 7.16) with increased anion-gap (value=18). She developed mal epilepticus needing thiopental induced coma and Intensive Care Unit (ICU) admission. She suffered prolonged symptoms including seizures before fully recovering.
The narrow therapeutic range and the increasing use in the treatment of smoking cessation boosted the number of intentional and unintentional poisoning by this drug. Previous reports of bupropion overdose almost all involve the immediate release formulation. There are some reports of overdose with sustained-release formulation, but there is limited information on its spectrum of toxicity.