Effect of some physiological changes on the binding of tenoxicam to human serum albumin

The influence of some physiological changes due to age or disease on the binding of tenoxicam to human serum albumin [HSA] was studied. Increasing HSA concentration within the range of 0.04% to 0.4% decreased the binding parameters, K1, n1 and n2. The presence of fatty acids decreased the affinity of HSA binding to tenoxicam at low protein concentrations. Urea as well as glucose increased the binding affinity of HSA to tenoxicam. The values of n1 and n2 were not significantly changed except when glucose was elevated to 500 mg/dL causing n1 and n2 to be nearly halved. Binding of tenoxicam to HSA increased as pH increased within the tested values of 6.8, 7.4 and 8. Consequently, tenoxicam was preferably bound by B rather than N form of HSA

Binding studies of some antidiabetics to serum albumin by difference spectrophotometry

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