Intrathecal antiepileptic drugs in experimental epilepsy.

The effect of intrathecal administration of antiepileptic drugs on electroshock-induced convulsions (maximal electroshock seizure, MES test) was investigated in an experimental study in rats. Drugs tested were phenobarbital sodium (50-800 micrograms), sodium valproate (50-6,400 micrograms) and midazolam (50-250 micrograms), delivered into the cerebrospinal fluid via a catheter placed in the upper cervical intrathecal space. Control animals were tested with saline. The animals were tested in the MES test 30 min after drug administration. Phenobarbital sodium showed a dose-related protective effect on the tonic phase of the convulsion, with a 50% effect at a dose of 200 micrograms. Sodium valproate showed a less protective effect, even when reaching doses that produced neurological symptoms. Midazolam protected at a high dose but produced a severe decrease in motor activity. The results indicate the feasibility to treat experimental convulsions by means of intrathecal injection of antiepileptic drugs.