phytonadione; vitamin K1; phylloquinone; phytomenadione; methylphytyl naphthoquinone (Mephyton, AquaMephyton)
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Introduction
Tradnames: Mephyton, AquaMephyton.
Indications
- coagulation disorders secondary to vitamin K deficiency
- hemorrhagic disease of the newborn
- abetalipoproteinemia[7]
- cholestasis[7]
Dosage
- 5-10 mg PO/IV/SC/IM BID PRN
- recheck INR 6-8 hours after parenteral administration or 12-48 hours after oral administration
- infants & children 1-2 mg every 4-8 hours IM/IV
Tabs: 5 mg.
Injection: 2 mg/mL (0.5 mL), 10 mg/mL (1 mL, 2.5 mL, 5 mL). .Recommended IV dosing to reverse coumadin excess (no bleeding)
- INR < 6: omit 1-2 doses of coumadin & restart at lower dose when INR is therapeutic
- INR = 6-10: vit K 0.5-1 mg slow IV/PO; may repeat in 24 hours if INR is still elevated; consider 2.5-5.0 mg orally#
- INR 10-20: vit K 3-5 mg slow IV*; may repeat in 6-12 hours if INR is still elevated
- INR > 20: vit K 10 mg slow IV*; may repeat in 12 hours if INR is still elevated
* vit K should be diluted & given not faster than 1 mg/min
# vit K 1.0 mg PO may be more appropriate[4] PO as effective as IV[5]
Injectable vitamin K can be given orally if < 5 mg dose[6]
Pharmacokinetics
- only absorbed from the GI tract via intestinal lymphatics in the presence of bile salts
- little is known about the metabolic fate of vitamin K
- coagulation factors II, VII, IX & X increase with 6-12 hours after oral administration & within 1-2 hours after parenteral administration
- following parenteral administration PT may normalize in 12-14 hours
elimination via liver
Adverse effects
- uncommon (< 1%)
- prolonged PT with high doses, GI distress, hemolysis in patients with G6PD deficiency, pain, sweating, tenderness at site of injection
- other
- anaphylactoid reactions have occurred, mostly with IV administration
- flushing sensation
- hypotension
Drug interactions
- phytonadione antagonizes effect of coumadin
- mineral oil may decrease absorption of vitamin K
More general terms
References
- ↑ The Pharmacological Basis of Therapeutics, 9th ed. Gilman et al, eds. Permagon Press/McGraw Hill, 1996
- ↑ Drug Information & Medication Formulary, Veterans Affairs, Central California Health Care System, 1st ed., Ravnan et al eds, 1998 Department of Veterans Affairs, VA National Formulary
- ↑ Kaiser Permanente Northern California Regional Drug Formulary, 1998
- ↑ 4.0 4.1 Journal Watch 22(19):150, 2002 Crowther MA et al, Ann Intern Med 137:251, 2002
- ↑ 5.0 5.1 Journal Watch 24(1):2, 2004 Lubetsky A et al Arch Intern Med 163:2469, 2003 PMID: https://www.ncbi.nlm.nih.gov/pubmed/14609783
- ↑ 6.0 6.1 Prescriber's Letter 13(10): 2006 Alternative or 'Off-label' Routes of Drug Administration Detail-Document#: http://prescribersletter.com/(5bhgn1a4ni4cyp2tvybwfh55)/pl/ArticleDD.aspx?li=1&st=1&cs=&s=PRL&pt=3&fpt=25&dd=221012&pb=PRL (subscription needed) http://www.prescribersletter.com
- ↑ 7.0 7.1 7.2 Deprecated Reference