From the Guidelines
When converting from oral to intravenous vitamin K, the dose should be reduced by about 80% due to the higher bioavailability of the IV route, with an oral dose of 5-10 mg being approximately equivalent to 1-2 mg IV 1. To determine the equivalent IV dose, consider the patient's current oral vitamin K dose and reduce it accordingly. For example, a patient taking 5 mg oral vitamin K daily would typically receive about 1 mg IV. Some key points to consider when administering IV vitamin K include:
- Administration rates should not exceed 1 mg per minute to avoid anaphylactoid reactions 1
- IV vitamin K has a faster onset of action (1-2 hours) compared to oral (24-48 hours), making it preferable in urgent situations like warfarin reversal with significant bleeding 1
- IV administration carries risks including anaphylaxis, flushing, and hypotension, so it should be reserved for cases where rapid correction is necessary 1
- Subcutaneous administration is an alternative when IV access is unavailable, though absorption may be less predictable 1
- Always monitor coagulation parameters closely when transitioning between routes to ensure therapeutic efficacy 1 In general, the choice between oral and IV vitamin K depends on the clinical situation, with IV administration preferred in urgent situations and oral administration suitable for less urgent cases. Some specific scenarios where IV vitamin K may be preferred include:
- Warfarin reversal with significant bleeding 1
- Urgent surgery or dental extraction 1
- Life-threatening bleeding or serious warfarin overdose 1 In these situations, the faster onset of action and more predictable response of IV vitamin K make it a better choice than oral administration. However, in less urgent cases, oral vitamin K may be sufficient, and the risks associated with IV administration can be avoided. Ultimately, the decision to use oral or IV vitamin K should be based on the individual patient's needs and the clinical situation, with careful consideration of the potential benefits and risks of each route.
From the Research
Comparison of Oral and Intravenous Vitamin K
- The study 2 compared the efficacy and safety of intravenous and oral phytonadione (vitamin K1) in patients with excessive anticoagulation, and found that oral administration had similar efficacy and safety as intravenous administration.
- Another study 3 compared intravenous and subcutaneous vitamin K1 in reversing excessive oral anticoagulation, and found that intravenous vitamin K1 resulted in a more prompt reduction in international normalized ratio (INR), but subcutaneous vitamin K1 was an effective and safe alternative.
- A retrospective review 4 estimated the incidence of anaphylaxis after intravenous phytonadione, and found that the incidence was 3 per 10,000 doses.
Safety and Efficacy of Intravenous Vitamin K
- A literature review 5 summarized the available literature on anaphylactic/anaphylactoid reactions with parenteral vitamin K1, and found that these reactions can result in severe hypotension, bradycardia or tachycardia, dyspnea, bronchospasm, cardiac arrest, and death.
- A clinical experience study 6 compared oral and intravenous vitamin K for warfarin reversal, and found that intravenous vitamin K was more effective for urgent partial correction of warfarin, but the dose administered had no influence on the postadministration INR.
Route of Administration
- The studies suggest that the route of administration of vitamin K (oral or intravenous) depends on the urgency of the situation and the patient's condition.
- Intravenous vitamin K may be more effective for urgent reversal of warfarin, but it also carries a risk of anaphylactic reactions.
- Oral vitamin K may be a safer alternative for non-urgent situations, but it may take longer to achieve the desired effect.