title: Stereospecific disposition of flunoxaprofen enantiomers in human beings.
abstract: The absorption and disposition kinetics of the enantiomers of the nonsteroidal antiinflammatory drug flunoxaprofen were studied in six healthy volunteers after oral administration of either R,S(+/-)-flunoxaprofen or R(-)-flunoxaprofen. The apparent values of the volume of distribution and systemic clearance of the S(+)-enantiomer were significantly lower than those of the R(-)-enantiomer. There was no significant difference in the absorption and elimination half-lives between the two isomers. The S(+)- to R(-)-isomer plasma concentration ratio increased with time with an apparent inversion half-time of about 50 h. This observation suggests metabolic inversion of R(-)- to S(+)-enantiomer, although the possibilities of stereoselective bioavailability or interaction between the two isomers can not be excluded.
authors.affiliation: Department of Pharmacology, University of Padua, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Palatini
authors.forename: G
authors.initials: G
authors.lastname: Montanari
authors.forename: A
authors.initials: A
authors.lastname: Perosa
authors.forename: A
authors.initials: A
authors.lastname: Forgione
authors.forename: S
authors.initials: S
authors.lastname: Pedrazzini
authors.forename: M
authors.initials: M
authors.lastname: Furlanut
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000097:blood / Q000493:pharmacokinetics*; D001583:Benzoxazoles / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D013237:Stereoisomerism
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001583:Benzoxazoles; C045356:flunoxaprofen