Pharmacokinetics, tissue distribution, metabolism, and excretion of ginsenoside Rg1 in rats

The pharmacokinetics, tissue distribution, metabolism, and excretion of ginsenosides Rg(1) were studied in Wistar rats, by measuring the concentrations of Rg(1) and its metabolites in the blood, tissues, bile, urine, and feces after dosing. After intravenous (i.v.) administration, the elimination half-lives of Rg(1) and its metabolites were 1.82, 5.87, and 6.87 h, and the area under the curves were 1595.7, 597.5, and 805.6 ng·h/mL, respectively. After oral administration, the elimination half-lives of Rg(1) and its metabolites were 2.25, 6.73, 5.44, and 5.06 h, and the area under the curves were 2363.5, 4185.5, 3774.3, and 396.2 ng·h/mL, respectively. After i.v. administration, Rg(1) and its metabolites were well distributed to the tissues analyzed except for the brain. The maximum concentration of Rg(1) was reached in all tissues at 5 min post dose, and it was eliminated from most of the tissues except for the kidney faster than it was eliminated from the blood. The maximum concentration of the metabolites was reached in all tissues between 4 and 6 h post dose. After i.v. administration, the recovery of the Rg(1) prototype in the urine and bile was 27.96% and 60.77%, respectively. The metabolism of Rg(1) in the intestine was via a hydrolization pathway, with the 6- and 20-glucoside bond hydrolyzed gradually under the catalysis of β-glucosaccharase, and then the metabolites were reabsorbed into the blood. Finally, the total recovery of the Rg(1) prototype and its metabolites in the urine and feces were 51.31% and 47.46%, respectively.