The relative bioavailability and pharmacokinetics of carbamazepine

Differences in the bioavailability after administration of two pure carbamazepine samples that were different in particle sizes have been found. Carbamazepine was given to each of 3 healthy male volunteers in a single oral dose of 400 mg in gelatin capsules. The other carbamazepine sample was administered after a three-week time interval. Plasma was collected during the following 96 hr. Quantitative determination of carbamazepine was performed by gas liquid chromatography. By comparing the areas under the various curves for each volunteer, the relative bioavailability of one of the carbamazepines in relation to the other one was found of approximately 70%. There were no differences in the half-life time.