Pharmacokinetic Study of Silybin in Healthy Chinese Subjects

In this study, a simple, rapid and sensitive high performance liquid chromatography (HPLC) method is developed for the determination of silybin in human plasma samples using midazolam as the internal standard (IS). Sample preparation was accomplished through one-step liquid-liquid extraction with ethyl acetate, and chromatographic separation was carried out on an Agilent ZORBAX Eclipse XDB-C18 column (4.6 x 150 mm, 5 pm) at 40 degrees C. Mobile phase composed of a mixture of acetonitrile-0.1% trifluoroacetic acid-water (44:31:25) at flow rate of 0.8 mL/min. Wavelength was set at 288 mu. The chromatographic retention times of silybin and IS were 435 and 5.52 min, respectively. The lower limit of quantitation (LLOQ) was 50 ng/mL, and no interferences were detected in the chromatograms. The devised HPLC method was validated by evaluating its intra- and inter-day precisions and accuracies in a linear concentration range between 50 and 6000 ng/mL. The method was successfully applied to a pharmacokinetic study of oral silybin capsules in Chinese healthy volunteers.