vitamin K1 (phytonadione) (Vitamin K, Mephyton, AquaMephyton)
Classes: Hemostatics; Vitamins, Fat-Soluble
Dosing and uses of Vitamin K, Mephyton (vitamin K1 (phytonadione))
Adult dosage forms and strengths
tablet
- 100mcg
- 5mg
injection emulsion
- 2mg/mL
- 10mg/mL
Nutritional Supplementation
Recommended daily intake (RDA)
Males: 120 mcg/day PO
Females: 90 mcg/day PO
Hypoprothrombinemia Due To Drugs or Factors Limiting Absorption or Synthesis
2.5-10 mg PO/IV/IM/SC; may be increased PRN to 25 mg or, rarely, to 50 mg; may be repeated in 12-48 hours
Reversal of Warfarin Effects
Omit 1-2 doses, or hold warfarin; monitor INR and adjust warfarin dose accordingly
INR 4.5-10, no bleeding: 2012 ACCP guidelines suggest against routine use; 2008 ACCP guidelines suggest considering vitamin K1 (phytonadione) 1-2.5 mg PO once
INR >10, no bleeding: 2012 ACCP guidelines recommend vitamin K1 PO (dose not specified); 2008 ACCP guidelines suggest 2.5-5 mg PO once; INR reduction observed within 24-48 hr, monitor INR and give additional vitamin K if needed
Minor bleeding, any elevated INR: Consider 2.5-5 mg PO once; may repeat if needed after 24 hr
Major bleeding, any elevated INR: 2012 ACCP guidelines recommend prothrombin complex concentrate, human (PCC, Kcentra) plus vitamin K1 5-10 mg IV (dilute in 50 mL IV fluid and infuse over 20 min)
NOTE: High vitamin K doses (ie, 10 mg or more) may cause warfarin resistance for a week or more; consider using heparin, LMWH, or direct thrombin inhibitors to provide adequate thrombosis prophylaxis in clinical conditions requiring chronic anticoagulation therapy (eg, atrial fibrillation)
Dosing Considerations
PO dose may be repeated in 12-48 hr and SC/IV/IM dose in 6-8 hr if necessary
IV rate not to exceed 1 mg/min
Use of high vitamin K doses (10-15 mg) may cause warfarin resistance for ≥1 week
Pediatric dosage forms and strengths
tablet
- 100mcg
- 5mg
injection emulsion
- 2mg/mL
- 10mg/mL
Nutritional Supplementation
RDA
0-6 months: 2 mcg/day
6-12 months: 2.5 mcg/day
1-3 years: 30 mcg/day
4-8 years: 55 mcg/day
9-13 years: 60 mcg/day
14-18 years: 75 mcg/day
Hemorrhagic Disease of the Newborn
Prophylaxis: 0.5-1 mg IM within 1 hr of birth
Treatment: 1 mg/dose/day SC; my require higher doses if mother has been receiving oral anticoagulants
Vitamin K, Mephyton (vitamin K1 (phytonadione)) adverse (side) effects
Frequency not defined
Anaphylaxis with too-rapid IV administration (has resulted in death)
Dyspnea
Cyanosis
Erythematous skin eruptions
Pruritus
Scleroderma-like lesions
Flushing
Hyperbilirubinemia (in premature neonates)
Hypotension
Injection site reactions
Taste alterations
Warnings
Black box warnings
Severe reactions, including fatalities, have occurred during and immediately after IV administration, even when precautions have been taken with proper dilution and avoidance of rapid infusion
Severe reactions also reported after IM administration; typically, these severe reactions involve hypersensitivity or anaphylaxis and include shock and cardiac or respiratory arrest
IV/IM reactions may occur with first dose (no prior exposure to phytonadione)
Restrict use of IV/IM routes to situations where SC administration is not feasible and serious risk involved is considered justified
Contraindications
Hypersensitivity
Cautions
Rapid IV administration may cause potentially fatal anaphylaxis
Protect from light; agent is rapidly degraded
Avoid IM route if patients is bleeding or in 3rd trimester of pregnancy
Administer phtonadione to quickly lower INR into safe range in patients receiving vitamin K antagonists
Other forms of vitamin K (eg, menadione) are not effective in these settings; only vitamin K1 (ie, phytonadione) should be used
Time of onset depends on rate of synthesis of clotting factors
Potential for overcorrection
Inefective in hereditary hypoprothrombinemia
Longer treatment durations (up to months) and much higher doses required in patients exposed to long-acting anticoagulant rodenticide
Hemolysis, hyperbilirubinemia, and jaundice reported in newborns treated with larger than recommended doses; use caution
Pregnancy and lactation
Pregnancy category: C
Lactation: Excreted in breast milk; use caution
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Vitamin K, Mephyton (vitamin K1 (phytonadione))
Mechanism of action
Promotes hepatic synthesis of clotting factors II, VII, IX, X (exact mechanism is unknown)
Pharmacokinetics
Onset: 6-10 hr (PO); 1-2 hr (IV)
Peak effect: 24-48 hr (PO); 12-14 hr (IV)
Metabolism
Metabolized in liver
Elimination
Excretion: Urine, feces
Administration
IV Administration
Dilute in preservative-free NS, D5W, or D5NS and infuse slowly; infusion rate not to exceed 1 mg/min
IV route should be used only if administration by another route is not feasible
Storage
Protect injection emulsion from light at all times
May be autoclaved