An HPLC method for the pharmacokinetic study of daidzein-loaded nanoparticle formulations after injection to rats

This study was aimed at developing a simple HPLC method for the detection of daidzein in rat plasma. Daidzein was extracted from rat plasma with ethylparaben as internal standards (IS). Chromatographic separation of daidzein and IS was achieved by a Dikma Dimonsil C18 column (200 mm × 4.6 mm) with the mobile phase consisting of methanol–water (55:45, v/v) at a flow rate of 1.0 mL/min. The injection volume was 20 μL and the detecting wavelength was 249 nm. The calibration curve was linear over a concentration range from 0.05 to 5 μg/mL, and the accuracy was within a range of 93.4–126.2%. This HPLC method was applied successfully to the pharmacokinetic study of two kinds of daidzein-loaded poly(lactide-co-glycolide) (PLGA) nanoparticles (D-NPs) and daidzein suspension after intravenous injection in rats. Significant differences in main pharmacokinetic parameters of daidzein suspension and D-NPs were observed.