title: [Difficult management of warfarin anticoagulant therapy due to S-1 administration for gastric cancer--report of a case].
abstract: A 72-year-old male with gastric cancer was referred to our hospital. The patient had been administered warfarin for cerebral infarction, aspirin and clopidogrel sulfate after percutaneous coronary intervention (PCI). Distal gastrectomy was performed for the lesion after discontinuing these drugs. After operation, warfarin was administered again as soon as possible, and on the other hand, we started treating the patient with S-1 for adjuvant chemotherapy carefully, because the interaction of each drug had been described before. On the sixth day after starting S-1, we reduced the amount of warfarin because PT-INR was elevated to a extremely high level of 6.84. Seven days later, PT-INR recovered to a slightly high level of 2.17. With continuation of S-1, PT-INR showed large fluctuations, so we needed to regulate the amount of warfarin carefully. It is important that we recognize the possibility of immediate interaction of two drugs and, before these drugs are administered, inform the patient about it.
authors.affiliation: Central Hospital.
authors.forename: Masahito
authors.initials: M
authors.lastname: Marutaka
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kubota
authors.forename: Ryousuke
authors.initials: R
authors.lastname: Yoshida
authors.forename: Youjirou
authors.initials: Y
authors.lastname: Orita
mesh_terms: D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000009:adverse effects; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage* / Q000009:adverse effects; D002544:Cerebral Infarction / Q000188:drug therapy; D017024:Chemotherapy, Adjuvant / Q000009:adverse effects; D004338:Drug Combinations; D005743:Gastrectomy; D006801:Humans; D008297:Male; D010094:Oxonic Acid / Q000008:administration & dosage* / Q000009:adverse effects; D013274:Stomach Neoplasms / Q000188:drug therapy*; D005641:Tegafur / Q000008:administration & dosage* / Q000009:adverse effects; D014859:Warfarin / Q000008:administration & dosage* / Q000009:adverse effects
chemical_list: D000925:Anticoagulants; D000964:Antimetabolites, Antineoplastic; D004338:Drug Combinations; C079198:S 1 (combination); D005641:Tegafur; D014859:Warfarin; D010094:Oxonic Acid