Amantadine hydrochloride for refractory generalized epilepsy in adults

Amantadine hydrochloride has been shown in several open studies to benefit children with refractory generalized epilepsy. We used amantadine as adjunctive therapy in 10 adolescents and adults with generalized tonic-clonic, myoclonic, or absence seizures refractory to therapeutic levels of valproate, carbamazepine, phenytoin, and benzodiazepines. Seven patients were men and 3 were women aged 18-29 years, and 8 of 10 patients were mentally retarded. All patients had generalized epileptiform paroxysms on EEG, with generalized or absence seizure recorded in 9. Five patients had both absence and tonic-clonic seizures, and 2 had all three seizure types. Amantadine was added to the existing regimens in weekly increments to 400 mg/day. Two patients had greater than 90 per cent seizure reduction, both with vomiting and somnolence. Two patients had seizure reduction between 50 and 90 per cent, 1 with anorexia and sleepiness. Three patients had no change in seizures, and 3 had worse tonic-clonic seizures. Amantadine may have some antiepileptic efficacy of unknown mechanism, but it may worsen generalized tonic-clonic seizures and is likely to be of limited value in adults.