Effect of high-dose cranberry juice on the pharmacodynamics of warfarin in patients.
BACKGROUND
Case reports suggest an association between cranberry juice and potentiation of warfarin. Studies using 240 ml of cranberry juice daily demonstrated no interaction. It is unknown if higher amounts of cranberry juice will interact with warfarin.


CONCLUSIONS
Cranberry juice at 240 ml twice daily does not alter the pharmacodynamics of warfarin.


OBJECTIVE
To determine if high-dose cranberry juice (240 ml twice daily) alters the pharmacodynamic action of warfarin.


METHODS
Ten male patients taking stable doses of warfarin were given cranberry juice at 240 ml twice daily for 7 days. Prothrombin times were drawn at baseline and days 2, 6 and 8 after administration of the juice. Prothrombin times were averaged for each day and mean times were compared from each study day to baseline using repeated measures ANOVA.


RESULTS
There was no statistical difference between mean prothrombin time at baseline and any day tested during juice administration.


CONCLUSIONS
Cranberry juice (240 ml twice daily for 1 week) did not alter the pharmacodynamics of warfarin in patients.
Mellen
Chadwick K
CK
Northern Arizona VA Health Care System, Prescott, AZ 86313, USA. Chadwick.Mellen@va.gov
Ford
Marjorie
M
Rindone
Joseph P
JP
D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000494:pharmacology* / Q000627:therapeutic use; D002318:Cardiovascular Diseases / Q000188:drug therapy*; D018565:Food-Drug Interactions; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011517:Prothrombin Time; D029799:Vaccinium macrocarpon / Q000009:adverse effects*; D014859:Warfarin / Q000494:pharmacology* / Q000627:therapeutic use
D000925:Anticoagulants; D014859:Warfarin