An analogue of Tolserol was found useful in the control of spells of idiopathic petit mal epilepsy. The drug is so rapidly excreted that unless one administers simultaneously a retarding agent such as cream or other fats or P.V.P. (Polyvinylpyrolidone) the drug may erroneously be thought to be ineffective. When used with a retarding agent the drug is effective for about 4 hrs. and benefits over 60% of the cases of idiopathic petit mal epilepsy. Like Tridione the drug tends to aggravate grand mal spells. When combined with Paradione or Tridione, particularly the former, the efficacy of both drugs is enhanced. Prenderol has an occasional muscle relaxing effect on patients with tension associated with extrapyramidal lesions. The drug is relatively non-toxic.