Binding of four sulphonamides to human albumin

The four sulphonamides studied--furosemide, tolbutamide, sulfafurazole and sulfonamidochlorobenzoic acid--bind to human albumin at the same sites but with decreasing affinity. These sites are also common to other drugs, namely acenocoumarin, chlorophenoxyisobutyric acid, phenylbutazone and warfarin. In plasma, the four sulphonamides considered bind mainly to albumin, but also, at higher concentrations, to globulins, to an extent that increases as their affinity for albumin lessens.