Status epilepticus was induced by injection of homocysteine thiolactone to rats with epileptogenic cortical cobalt lesions. Either standard phenytoin or ACC-9653 (a phenytoin prodrug) was injected after the second generalized tonic-clonic seizure. Rats treated with ACC-9653 had significantly poorer treatment outcomes than rats treated with standard phenytoin, although no differences were found in the concentration of phenytoin in plasma or brain 65 min after injection.