Determination and pharmacokinetic study of caudatin in rat plasma by UPLC

In this study, a simple, sensitive, and robust analytical method based on ultra-performance liquid chromatography (UPLC) has been developed for the determination of caudatin in rat plasma using midazolam as internal standard (IS). After sample preparation by a simple liquid-liquid extraction, chromatography was performed on an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 μm particle size) and ultraviolet detection set at a wavelength of 221 nm. The method was linear over the concentration range 25-400 ng/mL with a lower limit of quantification (LLOQ) of 25 ng/mL. Inter- and intra-day precision (RSD%) were all within 13% and the accuracy (RE%) was equal or lower than 6%. Recoveries of caudatin and IS were more than 82%. Stability studies showed that caudatin was stable under a variety of storage conditions. The method was successfully applied to a pharmacokinetic study involving oral administration of caudatin to rats.