American ginseng. III. Pharmacokinetics of ginsenosides in the rabbit.

The pharmacokinetics of ginsenosides A1, A2, B2, and C were studied in rabbits and were best described with a one-component open model. Ginsenoside C (protopanaxadiol group ginseng saponin) showed a significantly longer half-life, higher plasma protein binding, and lower metabolic and renal clearance than ginsenosides A1, A2, and B2 (protopanaxatriol group ginseng saponins). All ginsenosides except ginsenoside A1 were slowly absorbed after intraperitoneal administration. Ginsenosides were not found in rabbit plasma or urine samples after oral administration. The observed differences in the pharmacokinetics of the ginsenosides may be ascribed to differences in protein binding. Ginsenoside C was more toxic than ginsenoside A2 after intraperitoneal administration to mice. Toxicity was not observed after oral administration of any of the ginsenosides. The genins, panaxadiol and panaxatriol, were more toxic and had larger volumes of distribution than the ginsenosides.