Human serum albumin – Drug binding site 1 (HSA – Site 1)

Human serum albumin – Drug binding site 1 (Sudlow site I) is a major binding site on *serum albumin*, the most abundant protein in human plasma. This site, located in subdomain IIA of the albumin molecule, binds a wide range of endogenous substances (such as fatty acids and bilirubin) and many clinically important drugs, especially neutral and acidic molecules including warfarin, phenylbutazone, and others. Albumin acts as a molecular transporter, regulating the free concentrations and distribution of its ligands, which has important implications for pharmacokinetics and pharmacodynamics. The occupancy and functionality of site 1 can be altered in various disease states (e.g. liver disease, diabetes, inflammation), affecting drug efficacy and safety. Site 1 is thus considered a therapeutic target for understanding and managing drug interactions and certain disease conditions, though it is not a classical drug target like a receptor or enzyme[1][2][5].

Other names

Sudlow site IAlbumin site IHSA site Iwarfarin binding sitesubdomain IIA

Competitive or allosteric binding of drugs to site 1, modulating free fraction and distribution of drugs. Displacement interactions among drugs sharing this binding site. Modulation of albumin’s ligand-binding via posttranslational modifications (e.g. oxidation, glycation)[1][2]