Abstracts

RATIONALE: Zonisamide is a sulfonamide antiepilepsy drug that is approved for the treatment of partial seizures in adults with epilepsy. Zonisamide[ssquote]s antiseizure effects are believed to stem from its ability to block sodium and T-type calcium channels. Zonisamide is contraindicated in patients with documented sulfonamide allergies. The overall occurrence rate of hypersensitivity to sulfonamides is estimated at 3%, and the most commonly reported allergies involve sulfonamide antimicrobial agents (ie, [dsquote]sulfa drugs[dsquote]). Currently, the cross-sensitivity between sulfa drugs and zonisamide is unknown. This study was designed to investigate the reaction to dermatological testing with zonisamide in a patient reporting an allergy to sulfonamides.
METHODS: One epilepsy patient reporting allergies to sulfa-containing antimicrobial agents underwent dermatological testing for hypersensitivity to zonisamide. Three dilutions of zonisamide were applied to the skin of the patient to test for allergic reaction.
RESULTS: This patient who reported an allergy to sulfa drugs had a negative dermatological test for hypersensitivity to zonisamide. We will review all sulfa-containing drugs and their evidence for patient hypersensitivity and cross-reactivity to sulfa-containing anticonvulsants.
CONCLUSIONS: Though our experience is in only one patient, these results suggest that patients reporting allergies to sulfa drugs do not necessarily exhibit hypersensitivity to zonisamide. This information may be useful to clinicians with epilepsy patients who may benefit from zonisamide but report sulfa-drug allergies. Dermatological testing for hypersensitivity to zonisamide in such patients is warranted. Further investigation may reveal the degree of cross-sensitivity to sulfonamide antimicrobial agents and zonisamide.
Disclosure: Grant - Elan Pharmaceuticals. Consulting - Elan Pharmaceuticals. Stock - Elan Pharmaceuticals.