title: Transport and bioavailability studies of astragaloside IV, an active ingredient in Radix Astragali.
abstract: Astragaloside IV is an important constituent of Radix Astragali, a herbal remedy widely used in traditional Chinese medicine. Radix Astragali is administered orally but little is known about the transport properties and bioavailability of astragaloside IV. In this paper we report studies of the absorption of astragaloside IV in the perfused rat intestinal model, transport and uptake in Caco-2 cell monolayers and in vivo bioavailability in rat after an oral dose. In the perfused rat intestinal model, absorption of astragaloside IV was low from an aqueous solution but was significantly higher from a solution of Radix Astragali. Absorption was not affected by bile duct ligation. Transport through Caco-2 cells gave a very low permeability value (mean P(app) of 6.7+/-1.0 x 10(-8) cm/sec.) and uptake was unaffected by P-glycoprotein inhibitors. The absolute bioavailability of astragaloside IV in rat was 2.2%. The correlation between low permeability in vitro and poor bioavailability in vivo indicates in vitro absorption studies are useful in the evaluation of traditional Chinese medicines.
authors.affiliation: Center of Pharmacokinetics, China Pharmaceutical University, Nanjing, China.
authors.forename: Yongchuan
authors.initials: Y
authors.lastname: Gu
authors.forename: Guangji
authors.initials: G
authors.lastname: Wang
authors.forename: Guoyu
authors.initials: G
authors.lastname: Pan
authors.forename: J Paul
authors.initials: JP
authors.lastname: Fawcett
authors.forename: Jiye
authors.initials: J
authors.lastname: A
authors.forename: Jianguo
authors.initials: J
authors.lastname: Sun
mesh_terms: D000818:Animals; D001652:Bile Ducts / Q000601:surgery; D001682:Biological Availability; D018938:Caco-2 Cells; D004365:Drugs, Chinese Herbal / Q000493:pharmacokinetics / Q000494:pharmacology*; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D010477:Perfusion; D010539:Permeability; D051381:Rats; D017207:Rats, Sprague-Dawley; D012503:Saponins / Q000493:pharmacokinetics / Q000494:pharmacology*; D014315:Triterpenes / Q000493:pharmacokinetics / Q000494:pharmacology*
chemical_list: D004365:Drugs, Chinese Herbal; D012503:Saponins; D014315:Triterpenes; C052064:astragaloside A