MULTISITE BINDING OF FENOPROFEN TO HUMAN SERUM-ALBUMIN STUDIED BY A COMBINED TECHNIQUE OF MICRODIALYSIS WITH HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A simple and fast method for the determination of the multi-site bindi ng of fenoprofen (FP) to human serum albumin (HSA) has been developed by utilizing microdialysis sampling techniques combined with high perf ormance liquid chromatography (HPLC), The drug and protein were mixed in different molar ratios in 0.067 Mol potassium phosphate buffer, pH 7.4, and incubated at 37 degrees C in a water-bath. Then the microdial ysis probe was put in the FP-HSA solution and sampled at the perfusion rate of 1 mu L/min. The concentrations of FP in microdialysates were determined by the reversed-phase high performance liquid chromatograph y, Relative recovery (R) was also determined in vitro on similar condi tion, R is about 56.03+/-1.11% (n=3). Fenoprofen was found to bind to two classes of sites, the association constant (K-1) and the number of the binding sites on primary binding sites of a HSA molecule (n(1)) f or fenoprofen are 3.4 x 10(5)/M and 2.5, respectively, and those for s econdary binding are 1.0 x 10(4)/M and 10.0, respectively, The competi tive interaction of ibuprofen (IF) and palmitic acid with fenoprofen t o HSA were also studied, both compounds significantly decrease the bin ding degree of fenoprofen to HSA. (C) 1998 John Wiley & Sons, Ltd.