High-Performance Liquid Chromatography-Tandem Mass Spectrometry for Buprenorphine Evaluation in Plasma—Application to Pharmacokinetic Studies in Rabbits

The precise and reliable determination of buprenorphine concentration is fundamental in certain medical or research applications, particularly in pharmacokinetic studies of this opioid. The main challenge is, however, the development of an analytical method that is sensitive enough, as the detected in vivo concentrations often fall in very low ranges. Thus, in this study we aimed at developing a sensitive, repeatable, cost-efficient, and easy HPLC analytical protocol for buprenorphine in rabbit plasma. In order to obtain this, the HPLC-MS(2) system was used to elaborate and validate the method for samples purified with liquid-liquid extraction. Fragment ions 468.6→396.2 and 468.6→414.2 were monitored, and the method resulted in a high repeatability and reproducibility and a limit of quantification of 0.25 µg/L with a recovery of 98.7–109.0%. The method was linear in a range of 0.25–2000 µg/L. The suitability of the analytical procedure was tested in rabbits in a pilot pharmacokinetic study, and it was revealed that the method was suitable for comprehensively describing the pharmacokinetic profile after buprenorphine intravenous administration at a dose of 300 µg/kg. Thus, the method suitability for pharmacokinetic application was confirmed by both the good validation results of the method and successful in vivo tests in rabbits.