ABSTRACT
Carbamazepine (CBZ), an effective anticonvulsant, is metabolized in the liver by the mixed-function oxidase system to the active metabolite carbamazepine-10,11 -epoxide (CBZ-E). This chapter examines the effect of co-medication such as phenytoin, valproate, phenobarbital, and primidone on the metabolism of CBZ in epileptic patients. In addition to the associated drug therapy, it also examines the effect of CBZ dose on the serum CBZ and CBZ-E levels. The chapter discusses the clinical usefulness of routine monitoring of CBZ and CBZ-E concentrations. Studies have shown that a poor correlation exists between the CBZ dose and the serum concentration of CBZ and CBZ-E. A disproportionately small rise in the serum concentration of CBZ and CBZ-E was found in patients receiving CBZ monotherapy. Monitoring of drug levels therefore seems to be essential. However, in a review of antiepileptic drug monitoring it was concluded that clinical relevance for free CBZ and CBZ-E concentration monitoring in the presence of co-medication has not been established.
