A Case of Delayed and Persistent Carbamazepine Overdose Treated With Hemodialysis, Plasmapheresis, and Neostigmine

Carbamazepine is utilized for various indications. Due to its pharmacokinetic profile and drug properties, toxicity can be delayed and persistent despite supportive care. We report a severe case of intentional carbamazepine toxicity in a carbamazepine naive individual mimicking brain death that was not diagnosed until three days after consumption of carbamazepine when the patient was comatose. Symptoms of overdose persisted for several days despite attempted treatment with activated charcoal and whole bowel irrigation, hemodialysis, and plasmapheresis. Symptoms only began to improve with bowel evacuation as a result of administration of neostigmine intravenously plus hemodialysis and plasmapheresis additionally. Despite previous literature that reported success with hemodialysis and/or plasmapheresis we did not find either to be overly effective in our case possibly due to lack of ability to perform multidose activated charcoal and whole bowel irrigation. To our knowledge this is one of the few cases of carbamazepine overdose utilizing both hemodialysis and plasmapheresis but without activated charcoal and the only case report in which neostigmine was administered as an attempt to remove drug via the gastrointestinal tract with success.