Pharmacokinetics of Arctigenin and Fructus Arctii Powder in Piglets

Fructus arctii, also known as great power seed, is the dried fruit of Arctium lappa of the family Compositae. It is a commonly used veterinary herbal medicine, and arctigenin is the main active ingredient. The aim of this study was to characterize the absorption, distribution, metabolism, and excretion of arctigenin and Fructus arctii powder in piglets. These data were used to provide a theoretical reference for the development and clinical use of new veterinary drugs. Sixteen healthy piglets (mean weight 30.0 ± 5.0 kg) were divided into two groups. One group was administered 2.0 mg/kg body weight (bw) arctigenin intravenously, and the other was administered 1.0 g/kg^.bw Fructus arctii powder by gavage. Blood samples were collected from the anterior vena cava at different time points, and the concentration of arctigenin in the plasma of the piglets was determined using high-performance liquid chromatography (HPLC). Arctigenin conformed to a two-compartment model with no absorption, and the main pharmacokinetic parameters were as follows: distribution half-life (t _1/2α)-0.166 ± 0.022 h; elimination half-life (t _1/2β)-3.161 ± 0.296 h; apparent volume of distribution (V _d)-0.231 ± 0.033 L/kg; clearance rate (CL_b)-0.057 ± 0.003 L/(h.kg); and area under the curve (AUC)-1.189 ± 0.057 g^.h/mL. The pharmacokinetic parameters of arctigenin following oral administration of the Fructus arctii powder were as follows: absorption half-life (t _1/2ka)-0.274 ± 0.102 h, t _1/2α-1.435 ± 0.725 h, t _1/2β-63.467 ± 29.115 h, V _d-1.680 ± 0.402 L/kg, CL_b-0.076 ± 0.028 L/(h kg), peak time (t _max)-0.853 ± 0.211 h, peak concentration (C _max)-0.430 ± 0.035 g/mL, and AUC-14.672 ± 4.813 g/mL. These results indicated that intravenous arctigenin was sparingly distributed in tissues. In contrast, orally administered Fructus arctii powder was rapidly absorbed, more widely distributed, and more slowly eliminated than the intravenous arctigenin, which may indicate its sustained pharmacological effects.