Cranberry and warfarin interaction: a case report and review of the literature.
This case reports on a patient whose International Normalized Ratio (INR) increased after ingestion of cranberry sauce while stabilized on warfarin. It is followed by a review of the published literature on the potential interaction between the two.An 85-year-old woman on chronic warfarin therapy for atrial fibrillation experienced INR elevations of two- to three-fold after two separate ingestions of cranberry sauce. In each case, her INR values decreased after withholding three to four doses and resuming a similar maintenance dose of warfarin. Although the majority of the pharmacokinetic and pharmacodynamic studies did not find a significant interaction between cranberry and warfarin, several case reports indicate that cranberry products may increase INR values in patients on warfarin. Practitioners should consider cranberry usage as a potential contributor in the evaluation of supratherapeutic INR values in patients on warfarin.
Midwestern University College of Pharmacy, Glendale, AZ, USA.
Stacy L
SL
Haber
Kimberly A B
KA
Cauthon
Erin C
EC
Raney
D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D001281:Atrial Fibrillation / Q000188:drug therapy; D005260:Female; D018565:Food-Drug Interactions; D006801:Humans; D019934:International Normalized Ratio; D029799:Vaccinium macrocarpon / Q000009:adverse effects*; D014859:Warfarin / Q000378:metabolism / Q000627:therapeutic use*
D000925:Anticoagulants; D014859:Warfarin