Testing human hair for carbamazepine in epileptic patients: Is hair investigation suitable for drug monitoring?

Abstract

Hair samples were obtained from 30 patients who had been taking carbamazepine in fixed daily doses for more than 6 months. Carbamazepine was extracted from the hair by enzymatic hydrolysis and quantified by gas chro matography-mass spectrometry. Concentrations ranged from 1.2 to 57.4 ng mg-1. The concentrations of carba mazepine were significantly correlated (P < 0.0001) with the daily dose and the correlation coefficient was 0.793. Although it had been suggested by several authors that the measurement of carbamazepine in hair might provide a better index of individual dosage history than the plasma level assays, the deviations observed in this study led to the conclusion that hair samples are not suitable for eval uating the quantity of drug consumed. However, hair test ing may be useful for documenting clinical disorders by sectioning the shaft into segments corresponding to 1 month periods.