Friday, June 19, 2015

Rationale for Oral Vitamin K (Paeds)

Background

  • Vitamin K is necessary for synthesis of factors II (prothrombin), VII, IX, and X
  • Vitamin K is undetectable in cord blood
  • Lactobacillus (primary gut flora in breastfed babies) does not synthesize vitamin K
  • Breastmilk contains only small amounts of vitamin K (1 – 9 mcg/L); formula (53-66 mcg/L)

Oral Regimens

  • there is no licensed PO form in US, but parental form can be given orally
  • in countries that have gone to PO prophylaxis, failures (even with good compliance) have been reported .  Failures have not been reported with IM prophylaxis.
  • since multiple doses are required, compliance is an issue
  • advise parents regarding the increased risk of VKDB (exact numbers are unknown)
  • maternal dietary changes have little effect on overall vitamin K status of newborn
  • maternal vitamin K supplements of 5mg/day (800% RDA) has been shown in one study to raise infant serum levels to near formula-fed levels, but there is no FDA approved MVI that contains this amount of vitamin K

Absorption and Dose:

  • No specific recommendation on long term prophylactic dose of Vitamin K
  • oral administration vitamin K1 is absorbed from the small intestine.
  • The systemic availability following oral dosing is approximately 50%, with a wide range of interindividual variability. Absorption is limited in the absence of bile.
  • 2.5 to 5 mg orally once every 24 hours
  • Product leaflet recommends similar dose as per IM as the onset of action of action is approximately same for both the route
  • In terms of absorption, response to oral phytonadione is only slightly slower than response to the intravenous form
  • neonatal liver disease/ billiary atresia : 1mg OD

References:
  1. BNF for Children 2013
  2. http://www.medicines.ie/medicine/3250/SPC/Konakion+MM+Paed+Amps/
  3. http://www.drugs.com/dosage/phytonadione.html
  4. http://newborns.stanford.edu/VitaminK.html
  5. http://www.medsafe.govt.nz/profs/puarticles/vitk.htm

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