Determination of celecoxib in rat plasma by high-performance liquid chromatography with mass spectrometry detection and its application to pharmacokinetic studies

Rodica Cuciureanu1, Laurian Vlase2, Dana Muntean2, Magda Cuciureanu1, Mihai Nechifor1
1University of Medicine and Pharmacy, Iasi, Romania, 2University of Medicine and Pharmacy, Cluj-Napoca, Romania

A new sensitive and selective liquid chromatography coupled with mass spectrometry (LC/MS/MS) method for quantification of celecoxib (CLX) in rat plasma was developed and validated, in order to use it for the study of pharmacokinetic interactions between celecoxib and grapefruit juice. The CLX was separated on a reversed phase column (Zorbax SB-C18, 100 mm x 3.0 mm I.D., 3.5 μm) under isocratic conditions using a mobile phase of a 55:45 mixture of acetonitrile and 0.1% formic acid in water. The flow rate was 1 ml/min at the column temperature 40 °C. The retention time of CLX was 1.8 min. The detection of CLX was in MRM mode using an ion trap mass spectrometer with electrospray negative ionisation. The ion transitions monitored were m/z 380 to 316. Sample preparation: the plasma samples (0.2 ml) were precipitated using methanol. Calibration curves were generated over the range of 0.1-6.4 microg/ml. The values of precision and accuracy for CLX at quantification limit were 4.1% and 9.3% for intra-day determinations and 4.6% and 11.2% for inter-day determinations respectively. This is the first high-throughput reported method for analysis of CLX in rat plasma that uses protein precipitation as sample processing procedure and has a run-time less than 2 minutes. Being rapid, simple and selective, the method allows analysis of a great number of plasma samples from clinical study in short time. The validated LC/MS/MS method has been successfully applied to a pharmacokinetic interaction study between CLX and grapefruit juice in rats