Simultaneous determination of naproxen and esomeprazole in beagle dog plasma by supercritical fluid chromatography-tandem mass spectrometry coupled with evaporation-free liquid-liquid extraction.

In order to avoid a risk of gastrointestinal toxic caused by naproxen (NAP), esomeprazole (ESOM) is generally used clinically in combination. The present work was undertaken to simultaneously determine NAP and ESOM in beagle dog plasma, and evaluated their pharmacokinetic behaviors in beagle dogs. Herein, ethyl acetate was used to extract the samples by using a time-saving evaporation-free liquid-liquid extraction (EF-LLE) method, then the samples were analyzed by supercritical fluid chromatography tandem mass spectrometry (SFC-MS/MS). The optimal analysis conditions were achieved with an ACQUITY UPC2™ BEH column maintained at 50℃ and eluted completely within 2 min using supercritical carbon dioxide and methanol with a gradient elution mode. Due to the large differences in plasma concentrations between NAP and ESOM, celecoxib and diazepam were selected as dual-internal standards (IS). The mass transition ion pairs were m/z 231.2 → 185.0, 346.9 → 198.2, 285.1 → 193.1 and 382.2 → 281.2 for NAP, ESOM, diazepam (IS for NAP) and celecoxib (IS for ESOM), respectively. The concentration of NAP and ESOM were linear within the range of 0.1-100 μg/mL (r > 0.993) and 0.005-5 μg/mL (r > 0.996) in beagle dog plasma, and the accuracy and precision of intra-day and inter-day of all quality control samples were within ±15 %. It was a method with the feature of rapid, sensitive and high-throughput, and would be practical for determining NAP and ESOM in biological samples simultaneously and for assessing their pharmacokinetic behaviors in clinical studies.