Increased Valproate Serum Concentrations Upon Carbamazepine Cessation

Abstract
Valproate (VPA) serum concentrations (Cp) were followed in six epileptic mentally retarded patients when carbamazepine (CBZ) was discontinued. VPA Cp significantly increased when CBZ was discontinued. A new plateau of VPA Cp was achieved 4 weeks post-CBZ discontinuation. This time factor is analogous to the autoinduction property of CBZ. Careful VPA Cp monitoring is recommended when CBZ or other enzyme inducing agents are discontinued.