Warfarin resistance associated with intravenous lipid administration: discussion of propofol and review of the literature.

Intravenous lipids are often required for parenteral nutritional (PN) support in critically ill patients and are administered with continuous sedation if patients are receiving propofol, which contains soybean oil 10% as an emulsified preparation. High-dose propofol infusion was associated with reversal of enteral and intravenous warfarin anticoagulation in a 39-year-old woman with severe Crohn's disease. Despite increasing the daily dose of warfarin to 30 mg, anticoagulation was not achieved until propofol was discontinued. Reversal of anticoagulation recurred when PN support was supplemented with Liposyn II 20%. Lipid emulsions may interfere pharmacodynamically with warfarin activity by enhancing the production of clotting factors, facilitating platelet aggregation, or supplying vitamin K. They also may facilitate warfarin binding to albumin. Until further information regarding the mechanism of interference is elucidated, heparin therapy should be considered for initial anticoagulation in patients with intestinal absorptive deficiencies who receive high-dose lipid emulsions and require reliable anticoagulation. If warfarin is given, the international normalized ratio should be monitored daily to ensure adequate anticoagulation.