Converting Vitamin K1 Ampule to Oral Tablet
Oral administration of injectable vitamin K1 (phytonadione) is safe, effective, and can be used directly without reformulation—simply administer the contents of the ampule orally at the same dose. 1
Direct Conversion Approach
The injectable formulation can be administered orally by having the patient swallow the contents of the ampule directly. This approach is supported by multiple guidelines and research demonstrating that oral administration of injectable vitamin K1 is both effective and safe. 2
Key Conversion Points:
Dose equivalency is 1:1—if the patient is receiving 1 ampule (typically containing 1-10 mg) intravenously or intramuscularly once daily, the same dose can be given orally using the injectable preparation. 1
Oral bioavailability is predictable and effective, with the American College of Cardiology confirming that oral vitamin K1 administration produces reliable INR reduction within 24 hours. 1
Injectable vitamin K1 administered orally can be given as an undiluted solution directly from the ampule, or mixed with a small amount of juice or water if palatability is a concern. 2
Clinical Context Considerations
The appropriate oral dose depends on the clinical indication:
For INR 4-10 without bleeding: 1-2.5 mg oral vitamin K1 once daily is sufficient, which would be one 1-2 mg ampule given orally. 1, 3
For INR >10 without bleeding: 3-5 mg oral vitamin K1 is recommended, requiring a 5 mg ampule or multiple smaller ampules given orally. 1, 4
For nutritional supplementation in malabsorption or cystic fibrosis: 1-10 mg daily depending on age and severity, with the injectable formulation administered orally at the prescribed dose. 1
Important Caveats
Oral administration is NOT appropriate for emergency reversal—if rapid reversal is needed for active bleeding or emergency surgery, intravenous administration with prothrombin complex concentrate is required. 1, 3
The subcutaneous route should be avoided entirely, as absorption is unpredictable and sometimes delayed compared to oral administration. 1
Avoid high doses (≥10 mg) unless absolutely necessary, as they can cause warfarin resistance lasting up to one week and create a prothrombotic state. 1, 4
Practical Administration
The patient can drink the contents of the ampule directly, or it can be mixed with a small amount of liquid for easier administration. 2
Oral vitamin K1 takes 24 hours to substantially lower INR, so plan accordingly and do not expect immediate effects. 1
If transitioning from daily IV/IM ampules to oral tablets, vitamin K1 5 mg tablets can be substituted at the same daily dose once available, though injectable formulation given orally remains a cost-effective alternative. 2
Monitor INR 24-48 hours after the first oral dose to confirm appropriate response, especially in patients previously on parenteral therapy. 3
Cost and Availability Considerations
Injectable vitamin K1 administered orally provides a cost-effective alternative when oral tablets are unavailable or prohibitively expensive, as tablet costs have tripled in recent years. 2
The injectable formulation has proven stability and efficacy when used orally, making it a practical solution for both inpatient and outpatient settings. 2