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Evidence-Based Complementary and Alternative Medicine
Volume 2012 (2012), Article ID 308018, 8 pages
http://dx.doi.org/10.1155/2012/308018
Research Article

Pharmacokinetics and Relative Bioavailability of Flavonoids between Two Dosage Forms of Gegen-Qinlian-Tang in Rats

1School of Pharmacy, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan
2Department of Medical Research, China Medical University Hospital, Taichung 40402, Taiwan

Received 9 May 2012; Accepted 25 September 2012

Academic Editor: Chun Guang Li

Copyright © 2012 Chung-Ping Yu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Gegen-Qinlian-Tang (GQT), a popular Chinese medicine prescription, consists of Puerariae Radix, Scutellariae Radix, Coptidis Rhizoma, and Glycyrrhizae Radix. This study investigated the pharmacokinetics of GQT in rats and compared the bioavailability between two dosage forms, that is, traditional decoction (TD) and concentrated powder (CP). Rats were given TD and CP of GQT in a crossover design, and blood samples were withdrawn at predetermined time points. The quantitation methods of ten constituents in two dosage forms of GQT and in serum specimen using HPLC were developed and validated in this study. The pharmacokinetic parameters were calculated using noncompartment model. The results showed that daidzein, baicalein, wogonin, berberine, palmatine, and coptisine were not found in the circulation, whereas the sulfates/glucuronides of daidzein, baicalein, and wogonin were the major forms after oral administration of GQT. Comparison between two dosage forms indicated that the of daidzein sulfates/glucuronides after administration of CP was significantly lower than that of TD by 28.9%, whereas the bioavailabilities of baicalin/baicalein and wogonoside/wogonin were comparable between two dosage forms. In conclusion, the major flavonoids of GQT were extensively metabolized into sulfates/glucuronides and present as the major molecules in the circulation. TD of GQT revealed higher bioavailability of daidzin/daidzein than CP.