Pharmacokinetics of Two Ingredients of the Compound Chinese Herbal Medicine Transdermal Preparation in Cows

The topical administration of the compound Chinese herbal medicine transdermal preparation has been widely used in treating the mastitis of cows. In order to understand the metabolic process, four cows suffering from clinical mastitis were selected for the pharmacokinetic study. The transdermal preparation was applied to the diseased part of breast. Then the plasma and milk samples were collected respectively at 0, 0.5, 1, 2, 4, 6, 8, 10, 12, 24, and 36 h. The concentrations of baicalin and phillyrin in plasma and milk were determined by HPLC and the data of time-concentrations were analyzed by the pharmacokinetic software. The results showed that two ingredients in the plasma were not detectable, but they in the milk had linear relationship with the time. The peak concentration of baicalin [(2.84 ± 0.15) μg mL-1] appeared at (4.93 ± 0.35) h, AUC0-LOQ was (27.32 ± 7.91) mg L-1 h-1, and the mean retention time was (28.31 ± 0.49) h. The peak concentration of phillyrin [(0.49 ± 0.41) μg mL-1] achieved at (3.68 ± 3.14) h, AUC0-LOQ was (4.10 ± 0.31) mg L-1 h-1, and the mean retention time was (14.52 ± 0.02) h. These suggested that two ingredients had slow absorbing speed and high absorbing degree. They could not be eliminated in a short time, thus exerted the topical curative effect.