Simultaneous quantification of naproxcinod and its active metabolite naproxen in rat plasma using LC-MS/MS: Application to a pharmacokinetic study

摘要

In this study, a liquid chromatography-tandem mass spectrometry method was developed and validated to simultaneously determine naproxcinod and naproxen concentrations in rat plasma for the first time. Plasma samples were prepared by simple one-step extraction with methanol for protein precipitation using only 50 mu L plasma. Separation was performed on a Synergi Fusion-RP C18 column with a run time of 4 min. Naproxcinod, naproxen and internal standard concentrations were detected in the positive ion mode using multiple reaction monitoring (MRM) of the transitions at m/z 348.2 -> 302.2, 231.1 -> 185.1 and 271.2 -> 203.1, respectively. The calibration curves were linear, with all correlation coefficients being >= 0.9952, in the range of 1.00-400 ng/mL for naproxcinod and 20.0-8000 ng/mL for naproxen. Their accuracy was in the range of -8.1% to 8.7%, and the intra- and inter-day variations were <= 4.53%. The mean extraction recovery of all analytes was more than 93.1% efficient. Stability testing showed that naproxcinod and naproxen remained stable during the whole analytical procedure. After validation, the method was successfully applied to a pharmacokinetic study of naproxcinod and naproxen in rats. The AUC(0-infinity) of naproxen was 74.6 times larger than that of naproxcinod, which indicated that naproxcinod was rapidly metabolized into naproxen in rats. (C) 2014 Elsevier B.V. All rights reserved.