Successful prophylaxis against febrile convulsions with valproic acid or phenobarbitone.

A total of 184 six-month periods were analysed during which feverish illnesses occurred in children aged 6-42 months with a history of a febrile convulsion. Fits occurred in 34 out of 100 such periods when no treatment was being given, in six out of 45 periods when the serum phenobarbitone concentration was 69.0 mumol/l (1.6 mg/100 ml) or more, and in five out of 39 periods when the plasma valproic acid concentration was 416.4 mumol/l (6.0 mg/100 ml) or more. Thus in adequate dosage both phenobarbitone and valproic acid were significantly better than no treatment in preventing febrile convulsions (p less than 0.02). The two drugs were of comparable efficacy. It is concluded that with improved compliance valproic acid, which is relatively free from side effects, might be an effective prophylactic agent against febrile convulsions.