FACTORS INFLUENCING PLASMA-CONCENTRATIONS OF CARBAMAZEPINE AND CARBAMAZEPINE-10,11-EPOXIDE IN EPILEPTIC CHILDREN AND ADULTS

Plasma carbamazepine (CBZ) and carbamazepine-10,11-epoxide (CBZ-E) con centrations were measured in 160 epileptic patients in order to determ ine the effect of factors such as age, daily dosing schedule, formulat ion, and combination with other antiepileptic drugs on these concentra tions in relation to the daily dose. The results showed that the CBZ p lasma level/dose ratio was affected by all factors studied, whereas th e CBZ-E plasma level/dose ratio was affected only by formulation and a ge. The ratio of CBZ-E to CBZ plasma levels (CBZ-E/CBZ) was affected b y daily dosing schedule, age, and combination with other antiepileptic drugs. The present study demonstrated that many factors affect plasma CBZ/dose ratios, explaining the discrepancies observed in the literat ure.