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Stereospecific gas chromatographic method for determination of methadone in serum
Author(s) -
Kristensen K.,
Angelo H.R.
Publication year - 1992
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.530040410
Subject(s) - chemistry , stereospecificity , chromatography , methadone , gas chromatography , organic chemistry , pharmacology , catalysis , medicine
rac‐Methadone is used clinically for the chronic maintenance treatment of heroin addiction and for the relief of pain. As the pharmacological activity of methadone is due primarily to the (−)‐(R)‐enantiomer, stereospecific measurements of methadone serum concentrations in methadone‐treated patients are expected to be more relevant for clinical studies than earlier described total drug measurements. This study describes a stereospecific gas chromatographic (GC) method for the determination of methadone in serum. The extracted methadone was derivatizised with (−)‐menthyl chloroformate. The diastereometric derivatives were analysed by GC on a capillary column and detected with a nitrogen‐phosphorus detector. The resolution factor obtained for the methadone enantiomers was 1.1 with a relatively short time of analysis (30 min). By analysing the pure (−)‐(R)‐enantiomer, no racemization was seen during the analysis. The lower limit of quantitation was 75 nmol/1 for each enantiomer. Measurements of the ratio between (−)‐(R)‐ and (+)‐(S)‐methadone concentrations in serum from five methadone‐treated patients showed interindividual differences (range 0.5–1.1). The patient results correlated well with those from another GC method measuring total methadone.