Pharmacokinetic behavior of gentiopicroside from decoction of radix gentianae, gentiana macrophylla after oral administration in rats: A pharmacokinetic comaprison with gentiopicroside after oral and intravenous administration alone

Abstract

The pharmacokinetics in rats of gentiopicroside (GPS) from orally administered decoctions of <i>Radix Gentianae</i> (DRG) and <i>Gentiana macrophlla</i> (DGM) were compared with that of GPS alone administered at 150 mg/kg orally and 30 mg/kg intravenously. The metabolic profile of GPS after intravenous injection could be fitted to two-compartment model whereas oral administration decoctions DRG or DGM, or GPS alone, could all be fitted to a one-compartment model. After oral administration of GPS alone, GPS was absorbed quickly and reached a maximum plasma concentration (C_max) value, 5.78 ± 2.24 ¼g/mL within 0.75 ± 0.62 h. The plasma level of GPS declined with a T_1/2ke, 3.35 ± 0.76 h. After oral administration of decoctions DRG and DGM, GPS was absorbed and reached significantly higher maximum concentrations of 10.53 ± 3.20 ¼g/mL (p<0.01) and 7.43 ± 1.64 ng/mL (p < 0.05) at later time points 1.60 ± 0.76 (p < 0.01 ) and 2.08±0.74 h (p < 0.05), for DRG and DGM respectively, compared with oral GPS alone. Significantly larger AUC values were found for decoctions of GPS (83.49 ± 20.8 ¼g·h/mL for DRG and 59.43 ± 12.9 ¼g·h/mL for DGM) compared with oral GPS alone (32.67 ± 12.9 ¼g·h/mL). The results demonstrate that the bioavailability of GPS was markedly improved when administered as a decoction than as purified GPS. The decoction from <i>Radix Gentianae</i> provided 2.5 times better bioavailability and that from <i>Gentiana macrophlla</i> 1.8 times higher. The study confirms the importance of careful pharmacokinetic analysis in the characterization of herbal medicines when applied for future clinical applications.