Active metabolites in antiepileptic therapy. Reflections on a pharmacological joker.

Treatment with drugs that produce active metabolites in the organism may sometimes resemble playing cards that includes a joker. Both kinetically and dynamically the metabolites may be different from their parent compound, and antiepileptic drugs are no exception. Primidone, carbamazepine and valproate all have active metabolites, and the various problems which these mean for the treatment of epileptic patients are briefly discussed. Models for studying a parent compound and its active metabolite parallelly in man have been proposed for diazepam. These and other may be applied to antiepileptic drugs in order to increase the quality of their clinical use and the development of new drugs.