Which antiepileptic drug is most likely responsible for antiepileptic hypersensitivity syndrome in a 13-year-old recently started on a new drug?

• A. Carbamazepine
• B. Valproate
• C. Levetiracetam
• D. Gabapentin

Answer: (A)

Hypersensitivity reactions to antiepileptic drugs often involve immune-mediated responses that can include fever, rash, eosinophilia, and involvement of internal organs (sometimes called DRESS). The underlying mechanism is linked to metabolism of certain anticonvulsants into reactive arene oxide intermediates, which can trigger these widespread immune reactions. Among common antiepileptics, carbamazepine is a classic culprit because it is an aromatic anticonvulsant that undergoes this kind of bioactivation, and the hypersensitivity response typically emerges after a short period of exposure—weeks after starting the drug. Valproate is more known for hepatotoxicity and other distinct adverse effects, while levetiracetam and gabapentin are generally associated with a lower risk of this specific hypersensitivity syndrome. If this reaction occurs, the offending drug must be stopped promptly, and the patient requires supportive care, with consideration of systemic steroids if there is significant organ involvement.