title: Pharmacokinetics and bioavailability of beta-sitosterol in the beagle dog.
abstract: Tritium-labelled beta-sitosterol (BSS) 10 mg was administered to 6 beagle dogs in a 3-way crossover study: 1. i.v. solution, 2. p.o. powdered BSS, and 3. BSS embedded in a polyethyleneglycol (PEG) melt. The concentration-time profiles for both routes of administration were best described by a two-compartment open model with a fast distribution phase, having a t1/2 alpha of about 3 h, and a terminal disposition phase having a t1/2 beta of about 129 h. The volume of distribution of the central compartment corresponds to the total body fluid (Vc = 0.56 l/kg), and the apparent volume of distribution is about equal to the total body weight (V d/beta = 0.92 l/kg). The mean residence time is about 185 h. The absolute bioavailability upon p.o. administration is about 9%. The PEG embedment of BSS does not increase the extent of absorption; however, the rate of absorption is significantly increased.
authors.affiliation: University of Cincinnati Medical Center, Division of Pharmaceutics and Drug Delivery Systems, OH.
authors.forename: W A
authors.initials: WA
authors.lastname: Ritschel
authors.forename: U
authors.initials: U
authors.lastname: Kastner
authors.forename: A S
authors.initials: AS
authors.lastname: Hussain
authors.forename: H P
authors.initials: HP
authors.lastname: Koch
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D004285:Dogs; D007275:Injections, Intravenous; D012855:Sitosterols / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D012855:Sitosterols; C025473:gamma-sitosterol