STEREOSELECTIVE BINDING OF WARFARIN AND KETOPROFEN TO HUMAN SERUM-ALBUMIN DETERMINED BY MICRODIALYSIS COMBINED WITH HPLC

Microdialysis sampling technique combined with high performance liquid chromatography (HPLC) was utilized to determine the stereoselective b inding of warfarin and ketoprofen to human serum albumin (HSA) ii solu tion. The HPLC conditions for separation of warfarin aid ketoprofen en antiomers on HSA column were optimized. The unbound enantiomers in the mixed buffer (0.067 M phosphate and pH 7.4) solution of the drug race mate with HAS were sampled with microdialysis probe, and the amount of them was determined by HPLC on HSA column. It was observed that the u nbound concentrations of R-warfarin and R-ketoprofen are about 1.08 si milar to 1.34- and 1.08 similar to 1.15-fold of S-warfarin and S-ketop rofen, respectively, which indicated that the S-enantiomers bind to HS A more strongly than R-enantiomers to HSA. The interaction parameters for binding of warfarin and ketoprofen enantiomers to HSA including bi nding constants and number of binding site were obtained by the Scatch ard analysis of experimental data, and the stereoselectivity (alpha) c alculated by the binding constants of warfarin enantiomers to HSA is 1 .92, but that of ketoprofen enantiomers is very close. HSA exhibits st ronger stereoselectivity to warfarin racemate than to ketoprofen racem ate.