title: Warfarin resistance after total gastrectomy and Roux-en-Y esophagojejunostomy.
abstract: Nutritional deficiencies due to malabsorption occur after major gastric resection, and drugs that are primarily absorbed in the stomach or duodenum also are likely to exhibit decreased absorption. However, we performed a MEDLINE search (1960-2007) and found no evidence in the literature regarding the specific effects of warfarin absorption after total gastrectomy with Roux-en-Y gastric bypass procedure. We describe a 71-year-old woman receiving warfarin therapy for chronic atrial fibrillation who underwent a completion gastrectomy and Roux-en-Y esophagojejunostomy for an invasive adenocarcinoma of her gastric remnant. Before surgery, her international normalized ratio (INR) had been stable in her target range of 2-3 with warfarin 5-6 mg/day. At the time of her admission for the surgery, however, her INR was subtherapeutic at 1.73; warfarin was discontinued, and heparin and, subsequently, enoxaparin were used throughout her admission. After the surgery, the patient was discharged to a skilled nursing facility to continue bridge therapy with enoxaparin while warfarin was restarted and adjusted to a therapeutic INR of 2-3. Three months after discharge, the patient was hospitalized again for shortness of breath and was found to have an INR of 1.30 on admission, despite good compliance with her drugs. During this admission, the patient demonstrated resistance to warfarin therapy, requiring doses up to 20 mg/day to reach a therapeutic INR. To our knowledge, this is the first case report to demonstrate that patients undergoing a complete gastric resection followed by a Roux-en-Y gastric bypass procedure may display warfarin resistance. Close monitoring and dosage adjustment may be necessary to maintain therapeutic anticoagulation in these patients.
authors.affiliation: Department of Pharmacy Practice, University of Connecticut School of Pharmacy, Storrs, CT, USA.
authors.forename: Diana M
authors.initials: DM
authors.lastname: Sobieraj
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.forename: Orlando C
authors.initials: OC
authors.lastname: Kirton
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology / Q000601:surgery; D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis / Q000188:drug therapy; D002908:Chronic Disease; D004351:Drug Resistance; D004947:Esophagus / Q000601:surgery; D005260:Female; D005743:Gastrectomy / Q000379:methods*; D015390:Gastric Bypass / Q000379:methods*; D006801:Humans; D019934:International Normalized Ratio / Q000706:statistics & numerical data; D007583:Jejunum / Q000601:surgery; D013274:Stomach Neoplasms / Q000473:pathology / Q000601:surgery; D014859:Warfarin / Q000009:adverse effects / Q000493:pharmacokinetics / Q000627:therapeutic use*
chemical_list: D014859:Warfarin