title: An adverse interaction between warfarin and capecitabine: a case report and review of the literature.
abstract: Warfarin is one of the most commonly used oral anticoagulants in the clinic. It is well established that a wide range of antineoplastic drugs interact with warfarin, resulting in altered coagulation parameters and/or bleeding sequelae. While altered coagulation parameters have been observed in patients taking the oral 5-fluorouracil prodrug, capecitabine, in combination with warfarin, no report to date has described clinically overt evidence of bleeding. Herein, we report 2 cancer patients who presented with bleeding episodes that most likely resulted from an adverse interaction between capecitabine and warfarin after 6 weeks of concomitant therapy. In each case, there was a marked elevation in both the prothrombin time and international normalized ratio (> 10), with subsequent gastrointestinal bleeding. The exact mechanism of this interaction is yet unknown, but it is possible that capecitabine might, in some manner, reduce the hepatic metabolism of warfarin. Close monitoring of coagulation parameters is recommended for all patients receiving concomitant warfarin and capecitabine, with appropriate adjustment of warfarin dosage. The nature and extent of this interaction requires further investigation.
authors.affiliation: Saint Francis Cancer Center, Medical and Radiation Oncology Department, 2116 W. Faidley Avenue, Grand Island, Nebraska, USA. mcopur@sfmc-gi.org
authors.forename: M S
authors.initials: MS
authors.lastname: Copur
authors.forename: P
authors.initials: P
authors.lastname: Ledakis
authors.forename: M
authors.initials: M
authors.lastname: Bolton
authors.forename: A K
authors.initials: AK
authors.lastname: Morse
authors.forename: T
authors.initials: T
authors.lastname: Werner
authors.forename: M
authors.initials: M
authors.lastname: Norvell
authors.forename: J
authors.initials: J
authors.lastname: Muhvic
authors.forename: E
authors.initials: E
authors.lastname: Chu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000009:adverse effects* / Q000494:pharmacology; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D000069287:Capecitabine; D003841:Deoxycytidine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D004347:Drug Interactions; D005260:Female; D005472:Fluorouracil / Q000031:analogs & derivatives; D006470:Hemorrhage / Q000139:chemically induced*; D006801:Humans; D014859:Warfarin / Q000009:adverse effects* / Q000494:pharmacology
chemical_list: D000925:Anticoagulants; D000964:Antimetabolites, Antineoplastic; D003841:Deoxycytidine; D014859:Warfarin; D000069287:Capecitabine; D005472:Fluorouracil