Studies On Absorption And Pharmacokinetic Behavior Of Ginsenoside Rd

Objectives1. To develop a HPLC method for the determination of ginsenoside Rd in mice plasma;2. To study the oral bioavailability of ginsenoside Rd;3. To study the time course of Rd contents in the digestive tract after oral administration;4. To study the pharmacokinetic of enteric-coated capsules after oral administration in rats.MethodsAfter intravenous administration and oral administration, the concentrations of drug in mice blood were recorded by HPLC,plasma PK parameters were determined by noncompartmental and compartmental methods using the DAS software package; such samples as duodenumjejunum, ileum and colon included their contents at different time points after oral administration were taken out and analyzed by HPLC.Results1. Plasma Pharmacokinetic Studies in mice after intravenous administrationThe concentration-time curves fitted to a two- compartment model after intravenous administration. tl/2a was 0.334h, t1/2βwas 18.545h, Vd was 2.936L/kg, CLwas 0.008L/h/kg, AUCO-oo was 2590.413 mg/L*h.2.Plasma Pharmacokinetic Studies in mice after oral administrationIt showed that Rd in plasma were not detected after oral administration.3.The time course of Rd contents in the digestive tract after oral administrationThe amount of Rd in the gastric juice were degraded 71.77±4.8%, in the small intestine were 24.0±2.3% of the dose 1 hour after oral administration. Two hours later,when most of the Rd in the jejunum transferred into the ileum,the amount of Rd in the jejunum decreased to only 5.0±1.0% of the dose and that in the ileum increased largely to 23.0±6.0% of the dose. Then, that in the colon 5 hours later was as high as 8.0±4.4% of the dose,6 hours later,that in the small intestine was near the limit of detection and, on the contrary,19.8±13.7% of the dose was found in the colon. Ten hours later,ginsenoside Rd was not detected in the colon. 4. The plasma concentration and Rd contents in the colon after oral administration enteric-coated capsules in ratsIt showed that Rd in plasma were not detected after oral administration. Six hours later,the amount of Rd in the colon was only 18.2±10.67% of the dose, Then, that in the colon 8 hours later was 15.25±16.4% of the dose. Ten hours later,25.25±4.5% of the dose was found in the colon.ConclusionThe method was sensitive, accurate, rapid and can be applied to determine the ginsenoside Rd in plasma. The concentration- time curves fitted to a two- compartment model after intravenous administration. The amount of Rd in the intestine were stable and most of the Rd were found in the colon after oral administration, it is the pharmcokinetic basis of ginsenoside Rd in the treatment of ulcerative colitis.