Comparison of fluorescence polarization immunoassay and high performance liquid chromatography for determination of carbamazepine concentration in blood of poisoned patients.

Carbamazepine is an antiepileptic drug widely used by neurological and psychiatric patients. Because of it's low therapeutic index and increasing number of acute carbamazepine intoxications there is a need of routine serum carbamazepine assay in toxicological laboratories. Determinations of serum carbamazepine concentrations are 5.3% of all toxicological analysis carried on in Department of Analytical Toxicology and Therapeutic Drug Monitoring, Collegium Medicum, Jagiellonian University in Kraków. The goal of the study was comparison of two analysis methods: FPIA and HPLC-DAD for the diagnostics of patients intoxicated with carbamazepine. Material for analysis were 21 samples of blood collected from poisoned patients treated in Department of Clinical Toxicology in Kraków. Measurements of serum carbamazepine concentration by FPIA method and carbamazepine and it's main active metabolite carbamazepine-10,11-epoxide concentrations by HPLC-DAD method were made. Statistical analysis showed that serum carbamazepine concentrations measured by FPIA method were higher than serum carbamazepine concentrations measured by HPLC-DAD method (t21 = 2.21, p = 0.0384). The mean difference of serum carbamazepine concentrations measured by the two methods was 2.67 mg/l (SD = 5.69 mg/l) and didn't depend on the carbamazepine concentration measured by FPIA method (r = -0.137, p = 0.5431). There was no statistical difference between serum carbamazepine concentration measured by FPIA method and the sum of serum carbamazepine and carbamazepine-10,11-epoxide concentrations measured by HPLC-DAD method (t21 = 1.42, p = 0.1690).