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

Effects of antiepileptic drugs on various components (TF: tonic extension of forelimb, TH: tonic extension of hindlimb and CL: clonic convulsions or MCL: myoclonus) of maximal seizures induced by electroshock or pentylenetetrazol in mice were examined in order to classify these drugs. In addition, experiment was conducted similarly on the new anti-convulsant agent, 3-sulfamoylmethyl-1,2-benzisoxazole (AD-810), in order to assess this compound on the basis of the results with clinically useful antiepileptic drugs. From the results obtained in the present study, irrespective of the method, i.e. chemically or electrically induced seizures, anticonvulsant drugs tested can be classified into four main groups; 1) drugs (trimethadione, ethosuximide, nitrazepam, diazepam, erthotoin and metharbital) with an effect to antagonize all the whole seizure components. (TF, TH and CL or MCL) in an almost same antagonism, 2) 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, 3) drugs (diphenylhydantoin and carbamazepine) which selectively abolish both components (TF and TH) of tonic seizures, and 4) drugs (acetazolamide, sulthiame and primidone) exclusively blocking TH of tonic seizures. AD-810 demonstrated an antagonistic effect on tonic seizures but no on clonic ones with the same manner as seen with diphenylhydantoin and carbamazepine.