title: Effect of ciprofloxacin on the pharmacokinetics and pharmacodynamics of warfarin.
abstract: To determine if ciprofloxacin therapy alters the response to warfarin treatment, 36 adult patients attending three university-affiliated outpatient anticoagulation clinics randomly received a 12-day course of ciprofloxacin (750 mg twice daily) and a 12-day course of placebo; each course was separated by a 2-week washout period. Prothrombin times (PTs), concentrations of S-warfarin and R-warfarin (the isomers of warfarin), and concentrations of clotting factors II and VII were determined three times weekly for 9 weeks. By day 12 of ciprofloxacin therapy, concentrations of S-warfarin remained unchanged compared with those after placebo therapy, but R-warfarin concentrations increased significantly (1.15 times those after placebo therapy; P = .001); concentrations of clotting factors II and VII decreased (0.903 and 0.872 times those after placebo therapy, respectively, P < or = .020). The mean PT ratio after 12 days of ciprofloxacin therapy increased slightly (1.032 times that after placebo therapy; P = .057), but no patient had bleeding or a change in PT that required alteration in warfarin or ciprofloxacin therapy. We conclude that warfarin therapy is not a contraindication to the use of ciprofloxacin.
authors.affiliation: Department of Pharmacy and Pharmaceutics, Virginia Commonwealth University, Richmond 23298, USA.
authors.forename: D S
authors.initials: DS
authors.lastname: Israel
authors.forename: J
authors.initials: J
authors.lastname: Stotka
authors.forename: W
authors.initials: W
authors.lastname: Rock
authors.forename: C D
authors.initials: CD
authors.lastname: Sintek
authors.forename: A K
authors.initials: AK
authors.lastname: Kamada
authors.forename: C
authors.initials: C
authors.lastname: Klein
authors.forename: W R
authors.initials: WR
authors.lastname: Swaim
authors.forename: R E
authors.initials: RE
authors.lastname: Pluhar
authors.forename: J P
authors.initials: JP
authors.lastname: Toscano
authors.forename: J T
authors.initials: JT
authors.lastname: Lettieri
authors.forename: A H
authors.initials: AH
authors.lastname: Heller
authors.forename: R E
authors.initials: RE
authors.lastname: Polk
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000494:pharmacology*; D000925:Anticoagulants / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002939:Ciprofloxacin / Q000494:pharmacology*; D004311:Double-Blind Method; D004347:Drug Interactions; D005167:Factor VII / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011516:Prothrombin / Q000032:analysis; D011517:Prothrombin Time; D014859:Warfarin / Q000493:pharmacokinetics* / Q000627:therapeutic use
chemical_list: D000890:Anti-Infective Agents; D000925:Anticoagulants; D002939:Ciprofloxacin; D014859:Warfarin; D005167:Factor VII; D011516:Prothrombin