Fondaparinux and Phytonadione (vitamin K1) interaction
Fondaparinux and Phytonadione (vitamin K1): both prescribing labels describe an interaction that usually calls for monitoring, a dose change, or spacing the doses.
Usually manageable with monitoring or a dose change. Tell your pharmacist you take both.
What the FDA labels say
From the Fondaparinux (Fondaparinux Sodium) label · effective 2024-12-15
Do not administer agents that enhance the risk of hemorrhage with fondaparinux sodium unless essential for the management of the underlying condition, such as vitamin K antagonists for the treatment of VTE.
From the Phytonadione (vitamin K1) (PHYTONADIONE) label · effective 2026-03-24
Anticoagulants Phytonadione injectable emulsion may induce temporary resistance to prothrombin-depressing anticoagulants, especially when larger doses of phytonadione injectable emulsion are used.
Should this occur, higher doses of anticoagulant therapy may be needed when resuming anticoagulant therapy, or a change in therapy to a different class of anticoagulant may be necessary (i.e., heparin sodium).
Anticoagulants: May induce temporary resistance to prothrombin-depressing anticoagulants.
Phytonadione injectable emulsion does not affect the anticoagulant action of heparin.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.