Analysis of naltrexone and its metabolite 6-beta-naltrexol in serum with high-performance liquid chromatography.
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-β-naltrexol in human serum by using high-performance liquid chromatography (HPLC).


RESULTS
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.


CONCLUSIONS
Our results indicate that the developed method is suitable for determination of naltrexone and 6-β-naltrexol in human serum.
National Public Health Institute, Helsinki, Finland.
Pekka
P
Heinälä
Tuuli
T
Lahti
David
D
Sinclair
Kari
K
Ariniemi
Pirjo
P
Lillsunde
Hannu
H
Alho
D000085:Acetates / Q000737:chemistry; D000293:Adolescent; D000328:Adult; D000368:Aged; D000437:Alcoholism / Q000097:blood* / Q000188:drug therapy*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D059625:Liquid-Liquid Extraction; D008297:Male; D008875:Middle Aged; D009269:Nalorphine; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000097:blood* / Q000627:therapeutic use*; D009292:Narcotic Antagonists / Q000097:blood* / Q000627:therapeutic use*; D010472:Perchlorates / Q000737:chemistry; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D000085:Acetates; D009292:Narcotic Antagonists; D010472:Perchlorates; C006848:butyl acetate; C010410:6 beta-hydroxynaltrexone; D009271:Naltrexone; D009269:Nalorphine