Plasma concentrations of the enantiomers of methadone and therapeutic response in methadone maintenance treatment
Data(s) |
2000
|
---|---|
Resumo |
Methadone is a 50:50 mixture of two enantiomers and (R)-methadone accounts for the majority of its opioid effect. The aim of this study was to determine whether a blood concentration of (R)-methadone can be associated with therapeutic response in addict patients in methadone maintenance treatment. Trough plasma concentrations of (R)-, (S)- and (R,S)-methadone were measured in 180 patients in maintenance treatment. Therapeutic response was defined by the absence of illicit opiate or cocaine in urine samples collected during a 2-month period prior to blood sampling. A large interindividual variability of (R)-methadone concentration-to-dose-to-weight ratios was found (mean, S.D., median, range: 112, 54, 100, 19-316 ng x kg/ml x mg). With regard to the consumption of illicit opiate (but not of cocaine), a therapeutic response was associated with (R)- (at 250 ng/ml) and (R,S)-methadone (at 400 ng/ml) but not with (S)-methadone concentrations. A higher specificity was calculated for (R)- than for (R,S)-methadone, as the number of non-responders above this threshold divided by the total number of non-responders was higher for (R,S)-methadone (19%) than for (R)-methadone (7%). The results support the use of therapeutic drug monitoring of (R)-methadone in cases of continued intake of illicit opiates. Due to the variability of methadone concentration-to-dose-to-weight ratios, theoretical doses of racemic methadone could be as small as 55 mg/day and as large as 921 mg/day to produce a plasma (R)-methadone concentration of 250 ng/ml in a 70-kg patient. This demonstrates the importance of individualizing methadone treatment. |
Identificador |
http://serval.unil.ch/?id=serval:BIB_D9AFA531780D isbn:0376-8716 pmid:11064183 doi:10.1016/S0376-8716(00)00121-6 isiid:000166126800006 |
Idioma(s) |
en |
Fonte |
Drug and alcohol dependence, vol. 61, no. 1, pp. 47-54 |
Palavras-Chave | #Adult; Drug Administration Schedule; Female; Humans; Male; Methadone; Middle Aged; Narcotics; Opioid-Related Disorders; Sensitivity and Specificity; Stereoisomerism |
Tipo |
info:eu-repo/semantics/article article |