Determination of Plasma Warfarin Concentrations in Korean Patients and Its Potential for Clinical Application.
10.3343/kjlm.2009.29.6.515
- Author:
Min Jung KWON
1
;
Hee Jin KIM
;
Jong Won KIM
;
Kyung Hoon LEE
;
Kie Ho SOHN
;
Hyun Jung CHO
;
Young Keun ON
;
June Soo KIM
;
Soo Youn LEE
Author Information
1. Department of Laboratory Medicine and Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Warfarin;
Concentration;
INR;
Dose;
Korean
- MeSH:
Adult;
Aged;
Aged, 80 and over;
Anticoagulants/*blood/therapeutic use;
Asian Continental Ancestry Group;
Atrial Fibrillation/drug therapy;
Chromatography, High Pressure Liquid;
Female;
Humans;
Male;
Middle Aged;
Republic of Korea;
Tandem Mass Spectrometry;
Warfarin/analogs & derivatives/*blood/metabolism/therapeutic use
- From:The Korean Journal of Laboratory Medicine
2009;29(6):515-523
- CountryRepublic of Korea
- Language:English
-
Abstract:
BACKGROUND: Warfarin is a widely used oral anticoagulant with broad within- and between-individual dose requirements. Warfarin concentrations can be monitored by assessing its pharmacologic effects on International Normalized Ratio (INR). However, this approach has not been applied in the routine clinical management of patients receiving warfarin therapy. We performed a plasma warfarin assay using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) to determine if such an assay can be utilized in routine clinical practice. METHODS: We included a total of 105 patients with atrial fibrillation, and who were receiving warfarin for more than 1 yr. The plasma concentrations of total warfarin and 7-hydroxywarfarin were determined by HPLC-MS/MS (Waters, UK). We assessed the association between warfarin dose, concentration, and INR as well as the effects of these factors on warfarin concentrations. RESULTS: The mean maintenance dose of warfarin in 105 patients was 4.1+/-1.3 mg/day (range, 1.7-8.0 mg/day) and their mean plasma warfarin concentration was 1.3+/-0.5 mg/L. We defined a concentration range of 0.6-2.6 mg/L (corresponding to the 2.5th to 97.5th percentile range of the Plasma warfarin levels in the 74 patients showing INR within target range) as the therapeutic range for warfarin. The correlation of warfarin dose with warfarin concentration (r2=0.259, P<0.001) was higher than that with INR (r2=0.029, P=0.072). CONCLUSIONS: There was a significant correlation between warfarin dose and plasma warfarin concentrations in Korean patients with atrial fibrillation. Hence, plasma warfarin monitoring can help determine dose adjustments and improve our understanding of individual patient response to warfarin treatment.
