title: [Evaluation of Drug Interaction between S-1 and Warfarin].
abstract: Prolonged prothrombin time is observed in patients taking warfarin (WF) with a fluoropyrimidine, such as S-1. When WF is combined with S-1, the prothrombin time-international normalized ratio (PT-INR) and dose adjustment of WF should be closely monitored. To date, no clinical data have been reported in terms of the relation between temporal variation of PT-INR and its therapeutic range. In this study, we retrospectively collected patients' clinical data including PT-INR. We identified 21 patients receiving WF therapy before the start of S-1 treatment. Patient characteristics were male/female: 18/3, median age: 69 (range 48-81) years old, cancer of gastric/lung/pancreatic/other: 8/5/4/4, and history of deep vein thrombosis (DVT)/atrial fibrillation (AF)/cerebral infarction (CI)/other: 11/6/2/2. The PT-INR of 16 patients exceeded normal upper limits after taking S-1 with WF. The median time to exceed the PT-INR upper therapeutic range is 25 (range 3-77) days. Patients receiving WF anticoagulant therapy concomitant with S-1 should have their PT-INR closely monitored and WF doses adjusted accordingly.
authors.affiliation: Division of Pharmacy, National Cancer Center Hospital East.
authors.forename: Kaori
authors.initials: K
authors.lastname: Yamamoto
authors.forename: Shinya
authors.initials: S
authors.lastname: Suzuki
authors.forename: Kiwako
authors.initials: K
authors.lastname: Ikegawa
authors.forename: Hisanaga
authors.initials: H
authors.lastname: Nomura
authors.forename: Nozomu
authors.initials: N
authors.lastname: Fuse
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Saito
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use*; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use*; D004338:Drug Combinations; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy*; D010094:Oxonic Acid / Q000627:therapeutic use*; D011517:Prothrombin Time; D012189:Retrospective Studies; D005641:Tegafur / Q000627:therapeutic use*; D014859:Warfarin / Q000627:therapeutic use*
chemical_list: D000925:Anticoagulants; D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; C079198:S 1 (combination); D005641:Tegafur; D014859:Warfarin; D010094:Oxonic Acid