Open Access Open Badges Technical Note

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

Pekka Heinälä12, Tuuli Lahti135*, David Sinclair1, Kari Ariniemi1, Pirjo Lillsunde1 and Hannu Alho14

Author affiliations

1 National Public Health Institute, Helsinki, Finland

2 Finnish Foundation for Alcohol Studies, Helsinki, Finland

3 Department of Behavioural Sciences and Philosophy, University of Turku, Turku, Finland

4 Research Unit of Substance Abuse Medicine, University of Helsinki, Helsinki, Finland

5 THL, PL 30, 00271, Helsinki, Finland

For all author emails, please log on.

Citation and License

BMC Research Notes 2012, 5:439  doi:10.1186/1756-0500-5-439

Published: 15 August 2012



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-β-naltrexol in human serum by using high-performance liquid chromatography (HPLC).


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 NaH2PO4-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-β-naltrexol. The limit of quantification was 5.0 ng/ml for naltrexone and 1.0 ng/ml for 6-β-naltrexol. The analysed concentrations of naltrexone differed from the theoretic concentrations by 0.7 to 2.3% and those of 6-β-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-β-naltrexol; for the between-day assay it was 5.7% and 4.2%, respectively.


Our results indicate that the developed method is suitable for determination of naltrexone and 6-β-naltrexol in human serum.

Naltrexone; 6-β-naltrexol; High-performance liquid chromatography; Alcoholism