What is the recommended dose of Vitamin K1 (phytonadione) for newborns and adults?

Recommended Vitamin K1 (Phytonadione) Dosing for Newborns and Adults

For newborns, a single intramuscular dose of 0.5 to 1.0 mg vitamin K1 should be administered within one hour of birth; for adults, the recommended dose ranges from 2.5 to 10 mg for most indications, with up to 25-50 mg for severe cases. 1, 2

Vitamin K1 Dosing for Newborns

• Intramuscular (IM) administration is the preferred route for newborns due to its superior efficacy and reliability 3
• The recommended IM dose is 0.5 to 1.0 mg administered within one hour of birth 2, 1
• For parents who decline IM administration, oral vitamin K1 can be given using one of these regimens:
  • 3 × 2 mg orally at birth, at 4-6 days, and at 4-6 weeks 3
  • 2 mg orally at birth, followed by weekly doses of 1 mg for 3 months 3
  • Daily supplementation of 25 μg for exclusively breastfed infants following an initial 1 mg dose 4

Special Considerations for Newborns

• The oral route is not appropriate for preterm infants, infants with cholestasis, impaired intestinal absorption, or those too unwell to take oral vitamin K1 3
• For preterm infants on parenteral nutrition, the recommended dose is 10 μg/kg/day 2
• If an infant vomits or regurgitates within 1 hour of oral administration, the dose should be repeated 3
• For infants whose mothers have taken medications that interfere with vitamin K metabolism, additional monitoring and dosing may be required 3, 5

Efficacy and Safety Considerations

• IM administration has been shown to be more effective than oral administration in preventing late vitamin K deficiency bleeding (VKDB) 4, 6
• Preterm infants given 0.2 mg IM maintained adequate vitamin K status until a median age of 25 days without evidence of vitamin K epoxide accumulation, suggesting this lower dose may be appropriate for premature infants 7
• Parental refusal of vitamin K prophylaxis should be documented due to the risk of late VKDB 3

Vitamin K1 Dosing for Adults

• For correction of anticoagulant-induced prothrombin deficiency: 2.5 to 10 mg initially, with up to 25 mg in some cases 1
• For severe cases: up to 50 mg may be required in rare instances 1
• For hypoprothrombinemia due to other causes: 2.5 to 25 mg, with up to 50 mg rarely needed 1
• For adults on parenteral nutrition: 200 μg/day 2

Administration Considerations for Adults

• When administering intravenously, the injection should be given very slowly, not exceeding 1 mg per minute 1
• The maximum effect for IV administration occurs within 6-12 hours, while oral supplementation takes about 24 hours to reach full effect 2
• Subcutaneous administration should be preferred over IV when possible to avoid the small risk of anaphylactic reactions 1
• For patients on anticoagulant therapy, vitamin K administration may affect response to these medications, requiring monitoring of coagulation parameters 2

Monitoring and Follow-up

• The response to vitamin K supplementation (shortening of prothrombin time within 2-4 hours) can be diagnostic of hemorrhagic disease 1
• For patients with ongoing anticoagulant therapy, frequency and amount of subsequent doses should be determined by prothrombin time response 1
• In cases of shock or excessive blood loss, whole blood or component therapy may be indicated in addition to vitamin K 1

Vitamin K1 should be protected from light at all times, and parenteral preparations should be inspected for particulate matter and discoloration prior to administration 1.