title: Analysis of buprenorphine and its N-dealkylated metabolite in plasma and urine by selected-ion monitoring.
abstract: A selected-ion monitoring method was developed for determination of buprenorphine and its N-dealkylated metabolite (norbuprenorphine) in human plasma and urine. N-Propylnorbuprenorphine was added as internal standard to 2-3 ml of sample and the alkaloids were extracted with toluene-2 butanol at pH 9.4. After back-extraction in dilute sulphuric acid, the compounds were heated at 110 degrees C. This procedure led to quantitative loss of methanol followed by ring formation between the 6-methoxy group and the branched side-chain of all compounds. The derivatives were extracted into dichloromethane-2-butanol and treated with pentafluoropropionic anhydride. The resulting derivatives were suitable for selected-ion monitoring analysis. The coefficient of variation was found to be 4.5% at 5 ng/ml and 8.9% at 50 ng/ml in urine. The corresponding values for plasma were 6.2% and 5.3%, respectively. The lower limit of detection in plasma was 150 pg/ml, permitting analysis of plasma levels of buprenorphine for 24 h and urine levels of buprenorphine and norbuprenorphine for more than seven days after a therapeutic dose of buprenorphine. This method is the first with sufficient specificity and sensitivity for characterization of the clinical pharmacokinetics of buprenorphine.
mesh_terms: D002047:Buprenorphine / Q000031:analogs & derivatives / Q000032:analysis* / Q000097:blood / Q000652:urine; D055598:Chemical Phenomena; D002621:Chemistry; D003640:Dealkylation; D006801:Humans; D006868:Hydrolysis; D009019:Morphinans / Q000032:analysis*; D013997:Time Factors
chemical_list: D009019:Morphinans; D002047:Buprenorphine; C043585:norbuprenorphine