title: Pharmacokinetics of rac-leucovorin vs [S]-leucovorin in patients with advanced gastrointestinal cancer.
abstract: 1. The pharmacokinetics of [R]-leucovorin ([R]-LV), [S]-leucovorin ([S]-LV) and the circulating metabolite [S]-5-methyltetrahydrofolate ([S]-5-MTHF) were studied after administration of racemic LV and [S]-LV in 21 subjects. 2. After intravenous infusion of 600 mg m-2 rac-LV (group 1, n = 7) or 300 mg m-2 [S]-LV (group 3, n = 7), the decay of [S]-LV in plasma was biexponential with a distribution half-life of 0.8 to 1 h and an elimination half-life of 11 to 23 h. When rac-LV was administered as a 2 h i.v. infusion (400 mg m-2) following a loading dose of 200 mg m-2 (group 2, n = 7), the plasma concentrations of [R]-LV and [S]-5-MTHF decayed monoexponentially with mean (+/- s.d.) half-lives of 10 +/- 3 h and 7 +/- 2 h, respectively. 3. The AUC of [S]-5-MTHF was significantly higher after infusion of 300 mg m-2 [S]-LV than after infusion of 600 mg m-2 rac-LV (83 +/- 22 micrograms ml-1 h vs 53 +/- 22 micrograms ml-1 h; P = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine I, University of Vienna, Austria.
authors.forename: R M
authors.initials: RM
authors.lastname: Mader
authors.forename: G G
authors.initials: GG
authors.lastname: Steger
authors.forename: B
authors.initials: B
authors.lastname: Rizovski
authors.forename: A E
authors.initials: AE
authors.lastname: Sieder
authors.forename: G
authors.initials: G
authors.lastname: Locker
authors.forename: M F
authors.initials: MF
authors.lastname: Gnant
authors.forename: R
authors.initials: R
authors.lastname: Jakesz
authors.forename: H
authors.initials: H
authors.lastname: Rainer
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000378:metabolism*; D006207:Half-Life; D006499:Hepatic Artery; D006801:Humans; D007261:Infusions, Intra-Arterial; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D002955:Leucovorin / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D008875:Middle Aged; D013237:Stereoisomerism; D013763:Tetrahydrofolates / Q000097:blood*
chemical_list: D013763:Tetrahydrofolates; D002955:Leucovorin; C005984:5-methyltetrahydrofolate