Determination of buprenorphine, norbuprenorphine, naloxone, and their glucuronides in urine by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry method for the simultaneous quantification of buprenorphine (BUP), norbuprenorphine (NBUP), naloxone (NAL), and their glucuronide conjugates BUP-G, NBUP-G, and NAL-G in urine samples was developed. The method, omitting a hydrolysis step, involved non-polar solid-phase extraction, liquid chromatography on a C18 column, electrospray positive ionization, and mass analysis by multiple reaction monitoring. Quantification was based on the corresponding deuterium-labelled internal standards for each of the six analytes. The limit of quantification was 0.5 mu g/L for BUP and NAL, 1 mu g/L for NAL-G, and 3 mu g/L for NBUP, BUP-G, and NBUP-G. Using the developed method, 72 urine samples from buprenorphine-dependent patients were analysed to cover the concentration ranges encountered in a clinical setting. The median (maximum) concentration was 4.2 mu g/L (102 mu g/L) for BUP, 74.7 mu g/L (580 mu g/L) for NBUP, 0.9 mu g/L (85.5 mu g/L) for NAL, 159.5 mu g/L (1370 mu g/L) for BUP-G, 307.5 mu g/L (1970 mu g/L) for NBUP-G, and 79.6 mu g/L (2310 mu g/L) for NAL-G.

Automated summary

A method using liquid chromatography-tandem mass spectrometry was developed for simultaneous quantification of buprenorphine and its metabolites in urine samples, without the need for a hydrolysis step. The method was able to cover the concentration ranges encountered in a clinical setting.