title: Altered metabolism of orally administered loxoprofen in human subjects after an oral administration of loxoprofen for three consecutive days followed by a seven-day washout.
abstract: The effect of pretreatment (i.e., oral administration of loxoprofen for 3 consecutive days followed by a 7-day washout) on the pharmacokinetics and metabolism of the drug was studied in humans. In a control study, a Loxonin tablet (60 mg as loxoprofen anhydrous) was administered orally to 6 healthy male Korean subjects. In a pretreatment study, a Loxonin tablet was administered orally to the subjects once daily for 3 consecutive days. On the 10(th) day, a Loxonin tablet was administered orally to the subjects, and the concentrations of loxoprofen and the trans- and cis-alcohol metabolites in the plasma and urine were measured as a function of time. Using this pretreatment, the area under the curve (AUC) of the trans-alcohol metabolite of loxoprofen in the plasma, but not those of loxoprofen and the cis-alcohol metabolite, was increased (1.5-fold, p < 0.05), leading to increased contribution of the trans-alcohol metabolite to the total urinary recovery of loxoprofen (1.3-fold, p < 0.05). The urinary recovery of total metabolites, which was largely (> 90%) comprised of conjugate metabolites, was also increased as a result of the pretreatment (1.5-fold, p < 0.05). These results indicate that stereoselective reduction to trans-alcohol metabolites as well as the phase II metabolism of loxoprofen may be increased by such a pretreatment in human subjects.
authors.affiliation: Department of Pharmaceutics, College of Pharmacy, Seoul National University, Seoul 151-742, Korea.
authors.forename: In-Wha
authors.initials: IW
authors.lastname: Kim
authors.forename: Suk-Jae
authors.initials: SJ
authors.lastname: Chung
authors.forename: Chang-Koo
authors.initials: CK
authors.lastname: Shim
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism* / Q000652:urine; D019540:Area Under Curve; D004334:Drug Administration Schedule; D006801:Humans; D016018:Least-Squares Analysis; D008297:Male; D010666:Phenylpropionates / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism* / Q000652:urine
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D010666:Phenylpropionates; C040656:loxoprofen