Therapeutic failures in epileptic children due to impaired diphenylhydantoin bioavailability

The serum level approach to individualization of diphenylhydantion (DPH) therapy in epilepsy is well established. When universally applied it may help to reveal causes of inappropriate therapeutic responses. We report here a high rate of therapeutic failure with DPH in epileptic children, with widespread low serum DPH concentrations despite adequate doses. Impaired bioavailability of the local oral DPH formulation in use was confirmed by a crossover comparison with a standard imported oral formulation.