title: Warfarin resistance and enteral feedings.
abstract: Nutritional support via enteral feeding tubes may interfere with the response to medications by a number of mechanisms. A 31-year-old, white man was admitted after sustaining a gunshot wound to the chest and mandible. Subsequently, the patient developed pulmonary emboli documented by angiography. Attempts at anticoagulation with oral warfarin were unsuccessful while the patient was receiving 50-100 ml/hr of Osmolite through an Entriflex feeding tube and intermittent oral Ensure Plus supplements. Discontinuation of the Osmolite resulted in a prompt prolongation of the prothrombin time. The Ensure Plus was continued and adequate prothrombin times were achieved on 7.5 to 10 mg of warfarin daily. The total amount of vitamin K received from the enteral feedings ranged from 50 to 115 micrograms/day, which is less than the normal daily intake of 300 to 500 micrograms. Previous reports of warfarin resistance implicated older enteral feeding products with a much higher vitamin K content. Difficulty with anticoagulation may still be experienced with the newer formulations. It is unknown whether the vitamin K content or malabsorption of warfarin is the mechanism of resistance.
authors.affiliation: Department of Pharmacy, University of Cincinnati Medical Center, Ohio.
authors.forename: J E
authors.initials: JE
authors.lastname: Martin
authors.forename: D M
authors.initials: DM
authors.lastname: Lutomski
mesh_terms: D000328:Adult; D004333:Drug Administration Routes; D004351:Drug Resistance; D004750:Enteral Nutrition / Q000009:adverse effects*; D006801:Humans; D008297:Male; D011517:Prothrombin Time; D011655:Pulmonary Embolism / Q000188:drug therapy; D014812:Vitamin K / Q000008:administration & dosage; D014859:Warfarin / Q000008:administration & dosage / Q000494:pharmacology*; D014948:Wounds, Gunshot / Q000628:therapy
chemical_list: D014812:Vitamin K; D014859:Warfarin