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

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

BMC research notes (2012-08-17)
Pekka Heinälä, Tuuli Lahti, David Sinclair, Kari Ariniemi, Pirjo Lillsunde, Hannu Alho
ABSTRACT

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 NaH(2)PO(4)-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.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Butyl acetate, anhydrous, ≥99%
Sigma-Aldrich
Butyl acetate, ACS reagent, ≥99.5%
Sigma-Aldrich
Butyl acetate, suitable for HPLC, 99.7%
Supelco
Butyl acetate, analytical standard
Sigma-Aldrich
Butyl acetate, natural, ≥98%, FG
Sigma-Aldrich
Butyl acetate, ≥99%, FCC, FG
Sigma-Aldrich
Butyl acetate, ReagentPlus®, 99.5%
Supelco
Butyl acetate, Pharmaceutical Secondary Standard; Certified Reference Material
Supelco
Nalorphine hydrochloride solution, 1.0 mg/mL in methanol (as free base), ampule of 1 mL, certified reference material, Cerilliant®
Sigma-Aldrich
Butyl acetate, puriss. p.a., ACS reagent
Supelco
6β-Naltrexol solution, 1.0 mg/mL in methanol, ampule of 1 mL, certified reference material, Cerilliant®