Zonisamide

This sulfonamide-based anticonvulsant restricts the propagation and spread of seizures and suppresses epileptogenic focus activity. It has been used as first-line AED as well as an adjunct AED in dogs not adequately controlled by phenobarbital and bromide. Although some of it is metabolized by the P450 enzyme system, much is excreted unchanged in the urine. Dogs receiving concurrent drug therapy known to induce hepatic microsomal enzymes (ie, phenobarbital) require nearly twice the dosage of zonisamide to achieve and maintain serum concentrations than dogs receiving zonisamide alone.