Determination of unbound warfarin enantiomers in human plasma and 7-hydroxywarfarin in human urine by chiral stationary-phase liquid chromatography with ultraviolet or fluorescence and on-line circular dichroism detection
| Autor: | Sosuke Kimura, Harumi Takahashi, Masahiro Kajiwara, Nagisa Muramoto, Hirotoshi Echizen, Toshitaka Kashima, Hiromi Nakahata, Suzuko Kubo, Yoshiaki Shimoyama |
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| Rok vydání: | 1997 |
| Předmět: |
Circular dichroism
Chromatography Chemistry Circular Dichroism Analytical chemistry Absolute configuration Anticoagulants Stereoisomerism Blood Proteins General Chemistry Urine medicine.disease_cause Sensitivity and Specificity Fluorescence High-performance liquid chromatography Fluorescence spectroscopy Spectrometry Fluorescence medicine Humans Spectrophotometry Ultraviolet Warfarin Enantiomer Ultraviolet Chromatography Liquid Protein Binding |
| Zdroj: | Journal of Chromatography B: Biomedical Sciences and Applications. 701:71-80 |
| ISSN: | 0378-4347 |
| DOI: | 10.1016/s0378-4347(97)00346-0 |
| Popis: | Enantiomers of warfarin and 7-hydroxywarfarin in human plasma and urine, respectively, were determined by high-performance liquid chromatography using a cellulose-derivative column with UV or fluorescent detection, and their absolute configuration was determined simultaneously by a circular dichroism spectropolarimeter connected in series. Enantiomers of warfarin and its major metabolites [i.e., (R)-6-hydroxywarfarin, (S)-7-hydroxywarfarin and (RS)-warfarin alcohol] were well resolved. The method was precise and sensitive: within- and between-day coefficients of variation were9.6% for warfarin enantiomers in plasma and7.1% for 7-hydroxywarfarin enantiomers in urine, respectively, and the lower detection limits were 20 ng/ml for (R)-warfarin, 40 ng/ml for (S)-warfarin, 2.5 ng/ml for (R)-7-hydroxywarfarin and 4.5 ng/ml for (S)-7-hydroxywarfarin in 0.5 ml of both plasma and urine. The ultrafiltration technique was used for determining unbound concentrations of warfarin enantiomers in plasma using [14C]warfarin enantiomers resolved by the present HPLC system. Clinical applicability of the method was evaluated by determining unbound concentrations of warfarin enantiomers in five consecutive plasma samples obtained from a patient exhibiting an unstable anticoagulant response to warfarin (4 mg/day, p.o.). Results indicated that the present method would be useful in clarifying factors responsible for a large intra- and inter-patient variability in warfarin effects with regard to unbound plasma enantiomer pharmacokinetics. |
| Databáze: | OpenAIRE |
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