Novel Validated LC-MS/MS Method For Simultaneous Estimation of Celecoxib and Amlodipine in Rat Plasma and Its Application to A Pharmacokinetic Study

The combination of celecoxib (CLX) and Amlodipine (AMD) was approved for hypertensive patients with osteoarthritis by US-FDA. Hence, a potential analytical method that can simultaneously quantify these two drugs is required. In view of this, a novel and fully validated liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method has been established for the quantification of CLX and AMD in rat plasma simultaneously. protein precipitation extraction technique was employed for the extraction of analytes and their deuterated analogues from rat plasma quantitatively. The analytes were separated using the mobile phase comprising of acetonitrile–water with 0.1% formic acid buffer (70:30 v/v) and a flow-rate of 1.0 mL/min and 10 min run time on Agilent SB-C18 analytical column. The multiple reaction monitoring transitions, m/z 504.7→98.1 for CLX, 492.8→129.3 for AMD; 385.6→102.8 for CLX-D4 and 496.8.5→412.3 for AMD-D4 were utilized for the analysis in order to attain high selectivity. The method showed good sensitivity and linearity in the range of the concentration 20–800 ng/mL for CLX and 0.25–10 ng/mL for AMD respectively. Moreover, the method also displayed decent accuracy (87.9-100.27% and 99.28-103.26%) for CLX and AMD and precision according to US-FDA guidelines. The precision values for inter- and intra-day were between 1.92.02-7.085% and 0.083-3.43% and for CLX and AMD respectively. Further, the results of the pharmacokinetic parameters including Cmax, tmax, AUC0-t, AUC0-∞ and t1/2 values of drugs indicated that the developed method is valuable for the successful quantification of the analytes in rat plasma. The developed method is significant and is useful for simultaneous quantification of CLX and AMD.