title: A Study on Drug Interaction between Warfarin and Capecitabine with Special Reference to the Co-Administered Term or the Discontinuation Term of Capecitabine.
abstract: We used the prothrombin time international normalized ratio(PT-INR)to investigate the change in degree and term of warfarin following co-administration and after discontinuation of capecitabine. In this study, approximately 3 years of medical records of 7 patients receiving co-administration therapy of warfarin and capecitabine were obtained from 4 hospitals. We observed daily increases in PT-INR values up to peak PT-INR levels following co-administration of warfarin and capecitabine. Interestingly, the peak PT-INR values of 4 of the patients remained remarkably high despite discontinuation of capecitabine. The peak PT-INR values for concomitant warfarin and capecitabine were attained after an average of 31.3 days of usage. When compared with the average PT-INR values attained before co-administration, the PT-INR values following co-administration significantly increased by 3 times (p<0.05). After discontinuation of capecitabine for an average of 15.1 days, i. e., for approximately 14 days, the PT-INR values returned to the PT-INR values attained prior to co-administration. These results suggest that capecitabine has influence on the anticoagulant effect of warfarin during not only the co-administered term but also the discontinuation term, and that this influence occasionally continues after discontinuation of capecitabine. These findings also suggest that a period of approximately 14 days after discontinuation is necessary for the interaction of capecitabine to dissipate and the PT-INR values to return the levels attained before receiving concomitant warfarin and capecitabine.
authors.affiliation: Dept. of Pharmacy, Tenri Hospital.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Ikenishi
authors.forename: Mutsuaki
authors.initials: M
authors.lastname: Ueda
authors.forename: Akiko
authors.initials: A
authors.lastname: Kuroda
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Tsukazaki
authors.forename: Masahiko
authors.initials: M
authors.lastname: Nakao
authors.forename: Masashi
authors.initials: M
authors.lastname: Takeuchi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Konishi
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Matsuda
authors.forename: William
authors.initials: W
authors.lastname: Figoni
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohtori
authors.forename: Kenji
authors.initials: K
authors.lastname: Matsuyama
authors.forename: Hiroki
authors.initials: H
authors.lastname: Satoh
authors.forename: Yasufumi
authors.initials: Y
authors.lastname: Sawada
authors.forename: Eitaro
authors.initials: E
authors.lastname: Nakatsuka
mesh_terms: D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy*; D000069287:Capecitabine; D015179:Colorectal Neoplasms / Q000188:drug therapy*; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000031:analogs & derivatives; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome; D014859:Warfarin / Q000008:administration & dosage
chemical_list: D003841:Deoxycytidine; D014859:Warfarin; D000069287:Capecitabine; D005472:Fluorouracil