Dextromethorphan and carbetapentane: centrally acting non-opioid antitussive agents with novel anticonvulsant properties.

The non-opioid antitussives dextromethorphan and carbetapentane, the active ingredients of several over-the-counter cough suppressants, provide a dose-related protection against maximal electroshock seizures in rats. Both drugs, which bind with high affinity to the same site in the brain, potentiated the effects of the prototypic antiepileptic drug diphenylhydantoin. We propose that these novel anticonvulsant drugs may represent potentially useful therapeutic agents for the treatment of some forms of epilepsy, either alone or in combination with existing antiepileptic drugs.