Toggle Main Menu Toggle Search

Open Access padlockePrints

The influence of (R)- and (S)-Warfarin, vitamin K and vitamin K epoxide upon warfarin anticoagulation

Lookup NU author(s): Professor Farhad Kamali, Dr Tim Butler, Dr Hilary Wynne


Full text for this publication is not currently held within this repository. Alternative links are provided below where available.


The contribution of (R)- and (S)-warfarin enantiomers, vitamin K and vitamin K epoxide and patient factors to inter-individual variability in daily warfarin requirements were examined in a group of 73 patients. Simple correlation analysis showed a significant positive relationship between INR values and plasma (S)-warfarin concentrations (r = 0.25; p = 0.038). Multivariate analysis for relationships with INR demonstrated a highly significant positive relationship between INR and (S)-warfarin (p = 0.004) and plasma vitamin K epoxide concentrations (p = 0.028), and a significant negative relationship between INR and plasma vitamin K concentrations (p = 0.034). Twenty five percent of variation in INR could be explained by these variables (adjusted R2 = 0.25). Correlation analysis of data showed that warfarin dosage was significantly and negatively correlated with patient age (r = -0.42; p < 0.0001). Patient age accounted for 25% of variation in warfarin dosage requirements (R2 = 0.25). The combined effects of age and vitamin K appear to account for much of the inter-individual variability in warfarin dosage requirements.

Publication metadata

Author(s): Butler TJ; Kamali F; Wynne HA; Edwards C

Publication type: Article

Publication status: Published

Journal: Thrombosis and Haemostasis

Year: 2000

Volume: 84

Issue: 1

Pages: 39-42

ISSN (print): 0340-6245

ISSN (electronic):

Publisher: Schattauer GmbH


PubMed id: 10928467