DETERMINATION of NALTREXONE and ITS MAJOR METABOLITE 6-ß-NALTREXOL in SAMPLES
from HEROIN ADDICTS on NALTREXONE IMPLANTS TREATMENT
L.Olsen, A.S. Christophersen
National Institute of Forensic Toxicology, P.O. Box 495 Sentrum 0105 Oslo, Norway
A sensitive and specific high-performance liquid chromatographic (HPLC) method combined
with electrochemical (EC) and UV detection has been modified* and validated for the
analyses of naltrexone and its major metabolite 6-ß-naltrexol in plasma. The analytical
procedure includes liquid/liquid extraction with dichloromethane/isopropanol (19:1)
after alkalinazing (pH 9), back-extraction in phosphoric-acid (0,017 M) and direct
injection on a Guard column, 10 x 2 mm, which was coupled to Spherisorb 3 ODS-2,
100 x 4,6 mm, 3 mm, as analytical column, 40ºC, connected to both EC - and UV-detector.
Acetonitrile (28%)/phosphoric acid (40mM)/ SDS (2mM) was used as mobile phase,
flowrate 0.8 ml min Ketobemidon was used as internal standard (IS). The recovery
was found to be approximately 80% for both naltrexone, 6-ß-naltrexol and IS. RSD
for intra-day and inter-day variations were approximately 5% and 10%, respectively
for both naltrexone and 6-ß-naltrexol, while LOD was I ng/ml for both compounds.
The specificity of the method was tested by analyzing the most commonly abused
drugs. The method has been used for the analyses of plasma samples from heroin
addicts on naltrexone treatment used as implants (1g, duration 5-8 weeks).
Naltrexone and 6-ß-naltrexol concentrations varied from 1-7 ng/ml and 3-50 ng/ml,
independent of the number o days after the last implant.
*A.F. Davidson, T.A. Emm and H.J. Pieniasczek, J. Pharm. & Biom. Anal. 14 (1996) 1717.
Keywords: Naltrexone, metabolite, HPLC, heroin addicts, naltrexone implant treatment.
|
