Carbamazepine, carbamazepine-10,11-epoxide and phenytoin concentrations in brain tissue of epileptic children.

Carbamazepine (CBZ), carbamazepine-10,11-epoxide (CBZ-epoxide) and phenytoin (DPH) were measured in brain tissue in two epileptic children undergoing temporal lobectomy. The patients had been treated with the anticonvulsants in question for 2 years. The CBZ concentration in brain tissue was higher or equal to the plasma concentration. Brain/plasma ratio for CBZ was 1.0 and 1.4, respectively (grey substance). Brain/plasma ratio of CBZ-epoxide was 1.0. Concomitant treatment with DPH increased the percentage of CBZ-epoxide relative to CBZ in both brain and plasma. In white brain substance the concentration of CBZ, CBZ-epoxide and DPH was higher or equal to the corresponding concentration in grey substance. No major age-related differences in the distribution of anti-epileptic drugs between brain and plasma in these two children compared to adult epileptic patients were noted. A new quantitative thin-layer chromatographic method for the determination of DPH and phenobarbital (PB) in brain tissue and plasma is described.