Enteral feeds may contain sufficient vitamin K1 (commonly about 4 to 10 micrograms
per 100 mL) to antagonise the effects of
warfarin. One study in children reported that those receiving enteral nutrition (mostly vitamin K-enriched formula) required
2.4-fold higher maintenance
warfarin doses.
Starting or stopping
enteral feeds might affect dose requirements of vitamin K
antagonists (coumarins and indanediones). It is also possible that there is a local
interaction in the gut, as in one case separating the
administration of the
warfarin and an enteral feed by 3 hours or more was effective. Patients should be advised not to add or substitute dietary supplements such as Ensure without increased
monitoring of their coagulation status.