Severe cutaneous adverse reaction to drug excipient following brand-to-generic switch of levetiracetam.

Purpose: Levetiracetam is an antiepileptic drug known for its high tolerability, and severe adverse drug reactions are rare. We report the case of a severe cutaneous adverse drug reaction in a patient who was switched from brand-name to generic levetiracetam.

Summary: A 29-year-old woman undergoing contrast-enhanced computed tomography developed lesions over her trunk starting 6 hours after imaging. Although initially diagnosed as an allergy to the radiocontrast agent, the condition progressively worsened into toxic epidermal necrolysis-drug reaction with eosinophilia and systemic symptoms overlap syndrome, despite adequate hydration and treatment. Investigation of the patient's medications revealed that she had been switched from brand-name to generic levetiracetam a week before the onset of symptoms. Levetiracetam was immediately discontinued, with the patient recovering after 2 weeks of intensive care. Adverse drug reaction analysis identified excipients in generic levetiracetam as the likely cause of the severe reaction.

Conclusion: This is the first reported case of severe cutaneous drug allergy after a brand-to-generic switch for levetiracetam. Brand-to-generic switches of medications can potentially cause severe allergic reactions due to differences in excipients.