Serum albumin (Site 2)

Serum albumin is the most abundant plasma protein in humans, functioning primarily as a carrier for a wide range of endogenous and exogenous compounds, including hormones, fatty acids, and drugs. Site 2 is one of the principal drug-binding sites on albumin, distinct from the warfarin-binding Site 1. Drugs that bind at Site 2 may compete with each other, leading to clinically relevant drug–drug interactions and affecting their pharmacokinetics and biodistribution. The protein is critical for maintaining blood oncotic pressure and acts as a reservoir and transporter for small molecules. Alterations or competition at Site 2 can influence the free fraction of drugs in plasma and, therefore, their therapeutic and toxic potential. Serum albumin is most often considered in clinical pharmacology, especially when drug dosing must account for binding dynamics. Site 2 binding is an important consideration in the development of drugs with high protein affinity.

Other names

Albumin Site IIHuman serum albumin Site 2Albumin drug binding site 2HSA Site 2

Drug binding and transport; affects bioavailability, free drug concentration, and pharmacokinetics by non-covalent binding at Site 2 of albumin