Simultaneous Determination of Buprenorphine, Norbuprenorphine and Naloxone in Human Plasma by LC-MS-MS

A novel sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS-MS) method simultaneously determined buprenorphine (BUP) and its active metabolite, norbuprenorphine (NBUP), and a co-formulant, naloxone was developed, validated and applied successfully in humans. Buprenorphine-d(4) and norbuprenorphine-d(3) were used as the internal standard. The analysis was performed on a silica column, and the mobile phase was isocratic and composed of acetonitrile: 2 mM ammonium formate in H2O (82:18, v/v). Mass spectrometry employed multiple reaction monitoring modes with transitions of m/z 468.1-55.2 for BUP, 414.2-101.2 for NBUP, 328.3-310.3 for naloxone, 472.1-59.2 for buprenorphine-d(4) and 417.2-101.2 for norbuprenorphine-d(3). Lower limit of quantification (LLOQ) of the analytical method was 0.05 ng mL(-1) for BUP, 0.1 ng mL(-1) for NBUP and 0.025 ng mL(-1) for naloxone, respectively. The standard calibration curves of BUP, NBUP and naloxone were linear over the concentration range of 0.05-20 ng mL(-1), 0.1-20 ng mL(-1) and 0.025-20 ng mL(-1), respectively. The precisions (RSD) and accuracies (RE) of LLOQ and other QC samples were in acceptable range, with RSD < 20% and RE +/- 20% for LLOQ and RSD < 15% and RE within +/- 15% for QC samples. The method was accurate, precise and specific, and was applied to the pharmacokinetic study of buprenorphine in healthy volunteers.