Determination of celecoxib in human plasma and rat microdialysis samples by liquid chromatography tandem mass spectrometry

Methods for the determination of celecoxib in human plasma and rat microdia lysis samples using liquid chromatography tandem mass spectrometry are desc ribed. Celecoxib and an internal standard were extracted from plasma by sol id-phase extraction with C-18 cartridges. Thereafter compounds were separat ed on a short narrow bore RP C-18 column (30X2 nun). Microdialysis samples did not require extraction and were injected directly using a narrow bore R P C-18 column (70X2 mm). The detection was by a PE Sciex API 3000 mass spec trometer equipped with a turbo ion spray interface. The compounds were dete cted in the negative ion mode using the mass transitions m/z 380 --> 316 an d m/z 366 --> 302 for celecoxib and internal standard, respectively. The as say was validated for human plasma over a concentration range of 0.25-250 n g/ml using 0.2 ml of sample. The assay for microdialysis samples (50 mul) w as validated over a concentration range of 0.5-20 ng/ml. The method was uti lised to determine pharmacokinetics of celecoxib in human plasma and in rat spinal cord perfusate. (C) 2001 Published by Elsevier Science B.V.