A new high performance liquid chromatography method for the determination of regorafenib in plasma

Regorafenib is an oral multikinase inhibitor which is effective in the treatment of advanced local metastatic colorectal cancer, metastatic gastrointestinal stromal tumor (GIST) and hepatocellular cancer (HCC). In this study, a rapid, accurate and precise reverse phase high performance liquid chromatography (RP-HPLC) method with ultraviolet (UV) detection was developed for the determination of regorafenib in rat plasma. A simple, one-step precipitation method was developed for protein precipitation and methanol was used for extraction of regorafenib from plasma. A C18 column was selected for HPLC analysis. MeOH-water mixture (80:20, v/v) was found suitable as mobile phase system. The detector was set to a wavelength of 258 nm. The nilotinib drug substance was used as the internal standard. The peak areas of the regorafenib were divided to the peak areas of the internal standard, and these ratio of peak values were plotted against the concentration and linear calibration curves in the aqueous solution and plasma were obtained. The linearity of regorafenib in both standard solutions and plasma was 5-500 ng / mL. The limit of detection (LOD) and the limit of quantification (LOQ) values of the drug in aqueous solution were 1.23 ng / mL and 3.73 ng / mL, respectively; LOD and LOQ values in plasma were 1.55 ng / mL and 4.70 ng / mL, respectively. 93.82% recovery was obtained in plasma. The drug was administered to 10 healthy Sprague Dawley male rats at a dose of 5 mg / kg. Determination of the drug was performed in plasma samples of animals and the plasma concentration-time graph of regorafenib was obtained. Their pharmacokinetic parameters were Cmax: 364.41 ng / mL, tmax: 4 hour, t1/2: 11.8 hour, AUC(0-48): 5654.39 ng.hour / mL and AUC (0-∞): 6015.62 ng.hour / mL. The developed method is easy, sensitive, selective and repeatable and can be used in clinic laboratories and for the determination of regorafenib in biological fluids.