Delayed bupropion cardiotoxicity associated with elevated serum concentrations of bupropion but not hydroxybupropion.

CONTEXT: Bupropion overdose commonly causes generalized seizures and central nervous system depression. Less commonly, cardiotoxicity has been reported. The toxicity of the parent drug compared to its active metabolite hydroxybupropion is uncertain. CASE DETAILS: A 31-year-old man presented to the emergency department with altered mental status after an intentional overdose of bupropion. Three hours after admission he developed status epilepticus requiring intubation, and 13 h after admission he developed marked widening of the QRS complex and prolongation of the QTc interval. Serial serum bupropion levels peaked with the onset of cardiotoxicity (334 ng/mL) and fell into the therapeutic range within 24 h, which coincided with normalization of his ECG intervals. Levels of the metabolite hydroxybupropion peaked later (4302 ng/mL) and remained elevated even after neurological and cardiotoxic symptoms resolved. DISCUSSION: Cardiotoxicity appears to be caused primarily by bupropion rather than its active metabolite hydroxybupropion.

Metformin overdose-induced hypoglycemia in the absence of other antidiabetic drugs.

CONTEXT: Lactic acidosis is a well-recognized consequence of metformin. Hypoglycemia has been reported previously in metformin overdose, but the presence of other co-ingestions (e.g., a sulfonylurea) was not definitively excluded. CASE DETAILS: A 15-year-old girl ingested 75 g of metformin and 3 g of quetiapine. On examination in the emergency department 2 h later, she was drowsy but had normal vital signs. She developed lactic acidosis, hypotension, and recurrent and severe hypoglycemia (15 mg/dL and 20 mg/dL), requiring boluses of 50%dextrose. The first episode of hypoglycemia occurred approximately 4 h after ingestion. Serum metformin level 2 h after ingestion was 267 mg/L (therapeutic range, 0.465-2.5), and serum insulin was 2 mU/L (normal range, 6-35). Extensive laboratory investigation using high-resolution mass-spectrometry ruled out other possible hypoglycemic agents. She recovered after hemodialysis. DISCUSSION: Metformin overdose can cause severe hypoglycemia in the absence of other antidiabetic drugs. Potential mechanisms of metformin-induced hypoglycemia include decreased hepatic glucose production, decreased glucose absorption, and poor oral intake.