Differential antagonisms of anticonvulsants to various components of maximal seizures induced by electroshock or pentylenetetrazol in mice.

Abstract

Effects of antiepileptic drugs on various components (TF, tonic extension of forelimb; TH, tonic extension of hindlimb; CL, clonic convulsion; and MCL, myoclonus) of maximal seizures induced by electroshock or pentylenetetrazol in mice were examined to classify the drugs. An experiment was conducted similarly on the new anticonvulsant agent, 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), to assess this compound based on results with clinically useful antiepileptic drugs. Irrespective of the method, i.e., chemically- or electrically-induced seizures, anticonvulsant drugs tested can be classified into 4 groups: drugs (trimethadione, ethosuximide, nitrazepam, diazepam, ethotoin and metharbital) with an effect to antagonize all whole seizure components (TF, TH, CL or MCL) in an almost same antagonism; drugs (phenacemide, dipropylacetate, pheneturide, acetylpheneturide and phenobarbital) which inhibit all forms of seizures at relatively dissociated doses for the prevention of each component of seizures; drugs (diphenylhydantoin and carbamazepine) which selectively abolish both components (TF and TH) of tonic seizures; and drugs (acetazolamide, sulthiame and primidone) exclusively blocking TH of tonic seizures. AD-810 demonstrated an antagonistic effect on tonic but not on clonic seizures similar to diphenylhydantoin and carbamazepine.