Liquid Chromatography-Tandem Mass Spectrometry Method for Detection and Quantification of Meloxicam and 5′-Carboxymeloxicam in Oral Fluid Samples

Oral fluid testing offers a non-invasive alternative to blood sampling for monitoring drug exposure, but methods for detecting meloxicam and its metabolite in this matrix were not well established. This study developed and validated a fast LC-MS/MS method to detect and quantify meloxicam and its major metabolite, 5'-carboxymeloxicam, in oral fluid samples collected from 16 volunteers before and after a single meloxicam tablet dose, with pharmacokinetic parameters determined using Phoenix WinNonlin. The method demonstrated good linearity, accuracy, precision, and stability across relevant concentration ranges, and prostaglandin E2 was also successfully detected, demonstrating feasibility for combined PK/PD study designs. This validated oral fluid method offers a practical, minimally invasive tool for future meloxicam pharmacokinetic and pharmacodynamic research.