Document Detail


Over-the-counter vitamin K1-containing multivitamin supplements disrupt warfarin anticoagulation in vitamin K1-depleted patients. A prospective, controlled trial.
MedLine Citation:
PMID:  15543329     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Most multivitamin supplements contain far less vitamin K(1) than thought to affect warfarin anticoagulation. Having described 3 patients with multivitamin-warfarin interactions, we hypothesized that vitamin K(1)-depleted patients are sensitive to even small increments. Therefore, we compared the effect of a vitamin K(1)-containing multivitamin on warfarin anticoagulation between patients with low versus normal vitamin K(1) status. We screened 102 warfarin-treated patients and recruited nine with "low" (< 1.5 mcg/L, 10(th) percentile) (group 1) and 7 with "normal" (>4.5 mcg/L, median) (group 2) total vitamin K(1) plasma levels (vitamin K(1) + vitamin K(1) 2,3-epoxide). Patients received one multivitamin tablet containing 25 mcg of vitamin K(1) daily, for 4 weeks (period 1). A predefined algorithm was used to adjust warfarin doses if the INR was outside the therapeutic range. Patients requiring warfarin increments were then switched to 4 weeks of a vitamin K(1)-free multivitamin supplement (period 2). During period 1, subtherapeutic INRs occurred in 9/9 and 1/7 patients in group 1 and 2, respectively (p <0.001). In group 1, INR decreased by a median of 0.51 (p <0.01), and warfarin dose had to be raised by 5.3% (p <0.01), whereas INR and warfarin dose did not change significantly in group 2. During period 2 (7 patients), there were trends towards decreased total vitamin K(1) and rising INRs associated with significantly lower warfarin doses. We conclude that vitamin K(1)-containing multivitamins reduce INR in patients with low vitamin K(1) status. Our study suggests that vitamin K-depleted patients are sensitive to even small changes in vitamin K(1) intake.
Authors:
Daniel Kurnik; Ronen Loebstein; Hadas Rabinovitz; Naomi Austerweil; Hillel Halkin; Shlomo Almog
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Publication Detail:
Type:  Clinical Trial; Controlled Clinical Trial; Journal Article    
Journal Detail:
Title:  Thrombosis and haemostasis     Volume:  92     ISSN:  0340-6245     ISO Abbreviation:  Thromb. Haemost.     Publication Date:  2004 Nov 
Date Detail:
Created Date:  2004-11-15     Completed Date:  2005-05-24     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  7608063     Medline TA:  Thromb Haemost     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  1018-24     Citation Subset:  IM    
Affiliation:
The Division of Clinical Pharmacology and Toxicology and Anticoagulation Clinic, Sheba Medical Center, Tel Hashomer, Israel.
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MeSH Terms
Descriptor/Qualifier:
Adult
Aged
Aged, 80 and over
Anticoagulants / antagonists & inhibitors,  pharmacokinetics,  therapeutic use
Dietary Supplements
Drug Antagonism
Drug Monitoring
Female
Humans
International Normalized Ratio
Male
Middle Aged
Nonprescription Drugs
Vitamin K 1 / blood,  pharmacology*
Vitamin K Deficiency*
Warfarin / administration & dosage*,  antagonists & inhibitors,  pharmacokinetics*
Chemical
Reg. No./Substance:
0/Anticoagulants; 0/Nonprescription Drugs; 81-81-2/Warfarin; 84-80-0/Vitamin K 1

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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