Preliminary Observations of Plasma Carbamazepine Concentration in Epileptic Children

Abstract

A preliminary study on the plasma concentration of carbamazepine (Tegretol) in children was performed as related with the oral dosage.
Forty children at the pediatric seizure clinic of a university hospital (group A, aged 1-14, mean 8years) and 26 institutionalized both mentally and physically severely handicapped epileptic patients (group B, aged 5-23, mean 13 years) were selectedfor the study.
Plasma levels of carbamazepine, phenobarbital, etc. were determined by the modification of Kupferberg's. GLC methods.
In both groups A and B plasma carbamazepine Concentrations inμg/ml, plotted against dosage in mg/kg/day, showed great individual variation.
However, there was a definite tendency that the patients taking carbamazepine, but not phenobarbital or primidone, showed high plasma level/dosage ratio ofcarbamazepine; while the carbamazepine plasma level, or plasma level/dosage ratio, was low in those on both carbamazepine and barbiturates, especially in those with high phenobarbital concentration above potentially toxic level.
These probable drug interaction may have resulted in the differences of calculated values in both groups shown below.
In group A, plasma levels (3.58±2.43μg/ml) to dosage (12.5±3.27mg/kg/day) ratios of carbamazepine were 0.28±0.18; and group B presented 1.83±1.38μg/ml, 13.10±7.19 mg/kg/day and 0.15±0.11, respectively.