A new validated high-performance liquid chromatography method for the determination of regorafenib in rat plasma: Application for pharmacokinetic study

This study reports a rapid and sensitive reversed-phase high-performance liquid chromatography method with ultraviolet detection for the determination of regorafenib (REG) in rat plasma. For the extraction of REG from plasma and the precipitation of plasma proteins, a rapid one-step precipitation method was performed with methanol. The separation was performed in a methanol-water mixture (80:20, v:v) mobile phase system with a C18 column and monitored at a wavelength of 258 nm. Nilotinib was used as an internal standard. The linear dynamic range of REG was determined between 5 and 500 ng/mL in standard solution and plasma. The limit of detection of REG from the standard solution was found to be 1.23 ng/mL and the limit of quantitation was 3.73 ng/mL. The limit of detection of REG from plasma was found to be 1.55 ng/mL and the limit of quantitation was 4.70 ng/mL. Regorafenib was administered at 5 mg/kg to 10 healthy male Sprague Dawley rats, and pharmacokinetic results were evaluated. It exhibited a high recovery of 93.82% in plasma. Due to ease of sample preparation, high susceptibility, specificity, and certainty, the described method can be used successfully in the quantification of REG in in-vivo plasma and in routine analyses in clinical laboratories.