Binding studies of some antidiabetics to serum albumin by difference spectrophotometry

ABSTRACT

The binding of several antidiabetics to serum albumin was studied by difference spectrophotometry using a spectrophotometric probe 2-[4-hydroxy-benzeneazo] benzoic acid. The calculated constants for binding of the drugs to human serum albumin were 2.38x10[6], 1.78x10[6], and 1.87x10[4] for glyburide, tolbutamide and metformin respectively. While the values of binding to bovine serum albumin were 2.89x10[5], 2.04x10[5], and 2.14x10[4] for the same drugs. Drug-probe displacement studies showed that glyburide gave the greatest probe displacement followed by tolbutamide and metformin using both human and bovine serum albumins. This order of displacement of the anionic probe indicates that both hydrophobic character and ring substituents of the ligand contribute