Pharmacokinetics and metabolism study of firocoxib in camels after intravenous administration by using high-resolution bench-top orbitrap mass spectrometry

•A method to quantify firocoxib by high-resolution orbitrap mass spectrometry.•Method validated with excellent recovery, linearity, precision and accuracy.•Method was successfully utilized for firocoxib pharmacokinetic analysis in camels.•The method was used to tentatively identify firocoxib metabolite in camel plasma. In this study, we developed a high-resolution liquid chromatography mass spectrometry method for the pharmacokinetic study of firocoxib followed by full method validation. Following a solid-phase extraction, the firocoxib and internal standard (celecoxib) were separated on an Agilent Zorbax ZDB C18 column (50mm×2.1mm i.d., 3.5μm) with a gradient elution using methanol and 0.1% aqueous formic acid. Data acquisition was performed at 25,000 resolution with the automatic gain set to 1,000,000 and the maximum injection time of 100ms. Data were acquired in full-scan mode over a mass range of 100–550Da in positive electrospray mode. Linear calibration curves were obtained over the concentration ranges of 0.5–200ng/mL and no interfering peaks were detected at the retention time of firocoxib and internal standard in blank camel plasma samples. The mean extraction recoveries of firocoxib at three concentrations of 5, 25 and 75ng/mL ranged from 92 to 104%. Coefficient of variation of intra-day and inter-day precision were both