What is the proper technique for administering a 10 mg intramuscular injection of vitamin K1 (phytonadione)?

Administration of Vitamin K 10mg Injection

For a 10 mg dose of vitamin K (phytonadione), administer intravenously by slow infusion over 30 minutes, never exceeding 1 mg per minute, as rapid IV administration carries a risk of anaphylactic reactions that can result in cardiac arrest. 1, 2

Route Selection and Critical Safety Considerations

Intravenous Administration (Preferred for Urgent Situations)

• Dilute the 10 mg dose in 0.9% Sodium Chloride, 5% Dextrose, or 5% Dextrose and Sodium Chloride Injection using preservative-free diluents, and administer immediately after mixing 2
• Infuse slowly over 30 minutes, not exceeding 1 mg per minute to minimize the risk of severe anaphylactoid reactions 1, 2
• Anaphylactic reactions occur in 3 per 100,000 IV doses via a non-IgE mechanism, likely due to the polyoxyethylated castor oil solubilizer, and can cause cardiac arrest, severe hypotension, bradycardia/tachycardia, dyspnea, and bronchospasm 1, 3, 4
• Protect the solution from light at all times during preparation and administration 2
• Discard unused portions of diluted solution and unused vial contents immediately after use 2

Intramuscular Administration (Alternative Route)

• The FDA label states IM administration should be considered only when IV or subcutaneous routes are unavoidable, as IM injection carries risks of local tissue reactions 2
• Administer deep intramuscular injection if this route is selected, though IV is generally preferred for the 10 mg dose 2
• Scleroderma-like skin reactions can develop at IM injection sites, appearing as ivory indurated morphoeiform plaques ("cowboy's belt with revolver" pattern) that may persist for years after injection 5
• Severe anaphylactoid reactions have been reported with IM administration, including cases requiring emergency cesarean section 6

Oral Administration (Off-Label Alternative)

• Injectable vitamin K can be administered orally as an effective and safe alternative when the IV route poses excessive risk (e.g., history of anaphylaxis) or for non-emergency situations 3, 7, 8
• Oral administration achieves 95% INR reduction within 24 hours and carries no risk of anaphylaxis, making it the preferred route for non-bleeding elevated INR scenarios 9, 8
• The injectable formulation can be given undiluted orally or mixed with juice/water for palatability 7

Clinical Context for 10 mg Dosing

Life-Threatening Bleeding

• 10 mg IV vitamin K should always be co-administered with 4-factor prothrombin complex concentrate (PCC) 25-50 U/kg for immediate reversal in life-threatening bleeding 1, 3, 4
• Vitamin K alone is insufficient for emergent reversal, as PCC achieves INR <1.5 within 5-15 minutes while vitamin K alone takes hours 3, 9
• Co-administration is essential because factor VII in PCC has only a 6-hour half-life, requiring vitamin K to stimulate endogenous production of vitamin K-dependent factors 1, 3, 4

Major Non-Life-Threatening Bleeding

• 5-10 mg IV vitamin K by slow infusion over 30 minutes is appropriate for major bleeding without hemodynamic instability 1, 3, 9
• Consider adding PCC if bleeding is at critical sites (intracranial, intraspinal, intraocular, pericardial, retroperitoneal) or causing significant hemodynamic compromise 4

Severe Over-Anticoagulation Without Bleeding

• For INR >10 without bleeding, 5-10 mg can be given, but oral administration is preferred over IV to avoid anaphylaxis risk 1, 3, 9

Critical Dosing Caveats

• Never exceed 10 mg vitamin K in most clinical situations, as higher doses (>10 mg) create a prothrombotic state and cause warfarin resistance lasting up to one week 1, 3, 9
• High-dose vitamin K may require heparin bridging when warfarin needs to be resumed after the vitamin K effect wears off 3, 9
• In mechanical valve patients, use lower doses (1-2 mg oral) to avoid difficulty achieving therapeutic INR post-procedure and increased thrombosis risk 4

Monitoring After Administration

• Recheck INR 15-60 minutes after PCC administration (if given concurrently) to assess degree of correction 4
• Monitor INR regularly over the next week, as a minority of patients take over a week to clear warfarin and require additional vitamin K 1, 4
• Consider thromboprophylaxis as early as possible after bleeding control, as PCC use increases risk of venous and arterial thrombosis during recovery 1, 4

Common Pitfalls to Avoid

• Do not administer as rapid IV push, as this dramatically increases anaphylaxis risk 1, 2
• Do not use subcutaneous route for the 10 mg dose, as absorption is unpredictable and the FDA label recommends IV or IM for this dose 2
• Do not give vitamin K alone for life-threatening bleeding, as it takes hours to work and must be combined with PCC for immediate effect 3, 9
• Do not use preservative-containing diluents, especially in newborns, as benzyl alcohol has been associated with toxicity 2