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Published on: September 9, 2012
Study on warfarin plasma concentration and its correlation with international normalized ratio
Shujuan Sun1, Minghua Wang, Lequn Su
1Department of Pharmacy, Shandong Provincial Qianfoshan Hospital, Jinan 250014, PR China. sunshujuan@sdhospital.com.cn
Journal of Pharmaceutical and Biomedical Analysis
|July 25, 2006
Summary
A new HPLC method accurately measures warfarin in cardiac patients. Plasma concentration monitoring, not just INR, is crucial for precise warfarin dosage adjustment, especially when targeting ideal INR levels.
Area of Science:
- Pharmacology
- Analytical Chemistry
- Cardiovascular Medicine
Background:
- Warfarin is a critical anticoagulant for patients with cardiac valve replacements.
- Monitoring warfarin therapy is essential to prevent bleeding and thrombosis.
- Current monitoring methods, like INR, may not fully capture therapeutic efficacy.
Purpose of the Study:
- To develop and validate a sensitive High-Performance Liquid Chromatographic (HPLC) method for quantifying warfarin in patient plasma.
- To assess the correlation between warfarin dosage, plasma concentration, and International Normalized Ratio (INR).
- To determine the necessity of plasma warfarin concentration monitoring for optimal patient management.
Main Methods:
- Development of a sensitive, accurate, and reproducible HPLC assay for plasma warfarin.
- Validation of the HPLC method for linearity, recovery, and precision (inter-day and intra-day R.S.D.).
- Analysis of warfarin dosage, plasma concentration, and INR in 58 post-operative cardiac patients.
Main Results:
- The HPLC method demonstrated high accuracy, sensitivity, and reproducibility (R.S.D. <6.89%).
- Linearity was observed in the 0.12-3 microg/ml range with 94.6% mean recovery.
- Mean warfarin plasma concentration in patients was 567.6+/-122.3 ng/ml.
- Correlation between warfarin dosage/concentration and INR was poor, indicating limitations of INR alone.
Conclusions:
- The developed HPLC method provides a reliable tool for plasma warfarin determination.
- Direct warfarin concentration monitoring is essential for objective and accurate dosage adjustments.
- Plasma concentration monitoring is particularly valuable when achieving target INR levels is challenging.
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