- Start as soon as diagnosis is confirmed with VPA 10 mg/kg/d in two daily doses as NON-RETARDED FORMULA (please use Valproat-neuraxpharm®, Valproatneuraxpharm® Lösung, Ergenyl®, Ergenyl®-Lösung or Orfiril® Saft), increase by 10 mg/kg/d once per week up until recommended target serum level of 75-100 μg/ml is reached.