E-DRUG: Vitamin K1 (phytomenadione) and K3 (menadione) (4)
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Dear Wilbert,
In my opinion, there is no role for menadione (Vitamin K3) on national EMLs.
Micromedex states: [For Hypoprothombinemia] "the synthetic water soluble
forms of vitamin K (menadione, menadiol) have long been considered inferior
to vitamin K1 (Gilman et al, 1985). Additional evidence has been presented
to support this view (Udall, 1970)."
WHO is correct in listing phytomenadione (Vitamin K 1 ) as the preferred
form of Vitamin K. I also agree that there should be no square box to allow
for substitution of other forms of Vitamin K.
I do, however, believe that it is more advantageous to list the 5mg oral
tablet of phytomenadione versus the 10mg tablet listed in the WHO Model EML.
Countless studies conducted over the past several years consistently support
much lower dosing of phytomenadione than doses historically used (e.g.,
10mg).
Both the 2005 American Hospital Formulary Service Drug Information reference
and Micromedex suggest 2.5mg starting doses of oral Vitamin K1 for
anticoagulant-induced hypoprothrombinemia and hypoprothrombinemia from other
causes.
US national and institutional guidelines for anti-coagulation reversal suggest starting doses of 1-2.5mg of oral Vitamin K1 for anticoagulant-induced hypoprothrombinemia. Numerous studies support the efficacy of these lower doses and suggest a correlation between higher doses of Vitamin K1 and warfarin resistance. Studies also suggest that higher
doses of Vitamin K1 result in a much greater time to achieve therapeutic INR levels.
Doses of 0.5-2mg are used to treat hemorrhagic disease of the newborn.
These oral doses of 1-2.5mg are very difficult to administer using 5mg tablets which are scored only once. These small doses become even more difficult to administer using 10mg tablets.
Brenda Waning, MPH, RPh
Center for International Health and Development
Boston University School of Public Health
85 East Concord Street, 5th floor
Boston, MA 02118 USA
Tel: +1 617-414-1278 Fax: +1 617-414-1261
Email: bwaning@bu.edu