Effect of ciprofloxacin on the pharmacokinetics and pharmacodynamics of warfarin.
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.
Israel
D S
DS
Department of Pharmacy and Pharmaceutics, Virginia Commonwealth University, Richmond 23298, USA.
Stotka
J
J
Rock
W
W
Sintek
C D
CD
Kamada
A K
AK
Klein
C
C
Swaim
W R
WR
Pluhar
R E
RE
Toscano
J P
JP
Lettieri
J T
JT
Heller
A H
AH
Polk
R E
RE
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
D000890:Anti-Infective Agents; D000925:Anticoagulants; D002939:Ciprofloxacin; D014859:Warfarin; D005167:Factor VII; D011516:Prothrombin