Analysis of naltrexone and its metabolite 6-beta-naltrexol in serum with high-performance liquid chromatography

Abstract

Background: Naltrexone has been proven to be an effective treatment option for the treatment of alcohol dependency. In this article we introduce a reliable and simple method developed for the simultaneous determination of naltrexone and 6 - naltrexol in human serum by using high-performance liquid chromatography (HPLC). Findings. Liquid-liquid extraction with butyl acetate from basic solutions (pH 9) was chosen for extraction with nalorphine as an internal standard (IS). Analytes were back-extracted from organic solvent into perchloric acid. The acid extract was chromatographed by HPLC with a reverse-phase ODS-column and electrochemical detector. The mobile phase was a NaH 2PO4-solution with acetonitrile as an organic modifier and octanesulphonic acid and tetraethylammonium hydrogen sulphate as ion-pair reagents. The recovery of the extraction method was 48% for naltrexone and 75% for 6 - naltrexol. The limit of quantification was 5.0ng/ml for naltrexone and 1.0ng/ml for 6 - naltrexol. The analysed concentrations of naltrexone differed from the theoretic concentrations by 0.7 to 2.3% and those of 6 - naltrexol by 2.6%. The relative standard deviation of within-day assay was from 0.9 to 5.7% for naltrexone and from 0.8 to 4.2% for 6 - naltrexol; for the between-day assay it was 5.7% and 4.2%, respectively. Conclusions: Our results indicate that the developed method is suitable for determination of naltrexone and 6 - naltrexol in human serum. © 2012 Heinälä et al.; licensee BioMed Central Ltd.