Acute Topiramate Toxicity in a Five-Year-Old Child

Topiramate (TOPAMAX®) is an anti-epileptic drug for which acute toxicity is infrequently reported. We present the case report of a five-year-old, otherwise healthy boy who presented to the emergency department (ED) for symptoms of acute encephalopathy. He was lethargic, having slurred speech, hallucinating, intermittently agitated, and had multiple episodes of urinating on himself. Computed tomography (CT) of the head, lumbar puncture, electroencephalography, and magnetic resonance imaging (MRI) were all normal. The urine drug screen was also negative. Two days after admission, a saliva toxicology screen was significant for a topiramate level of 3487.8 ng/ml, which he was not taking and which his mother admitted taking for weight loss. The patient was observed for two days, over which time his symptoms completely resolved, and he was back to baseline. The following is the take-away for physicians: Careful history-taking should bedone to identify potential drug exposures in children presenting with acute encephalopathy. Especially, given the emerging off-label use of drugs, like in this case, topiramate, which was used by the mother for weight loss. We postulated a possible idiosyncratic reaction vs true drug toxicity, which correlates with findings in a previous case reportout of Boston Children's Hospital by Taub et al.; and in this case, serum level was about one-third the reported level in this case report^. The patient presented with comparable symptoms and time to recovery.