Serum albumin (SA) (SA)

Serum albumin is the most abundant protein in mammalian plasma, synthesized primarily in the liver and essential for maintaining colloid osmotic pressure [1][2]. It functions as a versatile transport protein, binding and carrying a wide array of endogenous ligands such as fatty acids, bilirubin, and hormones, as well as exogenous drugs [3]. In clinical pharmacology, albumin is a critical determinant of drug pharmacokinetics, as only the unbound "free fraction" of a drug is typically pharmacologically active [4]. While not a traditional signaling receptor, it is a major target for drug delivery systems, such as albumin-bound nanoparticles (e.g., nab-paclitaxel), which exploit its long half-life and natural accumulation in inflamed or malignant tissues [5]. Bovine serum albumin (BSA) is frequently used in laboratory research as a biochemical surrogate for human serum albumin (HSA) due to their high structural similarity [6]. Pathological conditions like liver cirrhosis or nephrotic syndrome can lead to hypoalbuminemia, significantly altering drug distribution and increasing the risk of toxicity [2][4].

Other names

AlbuminHuman serum albuminBovine serum albuminALBHSABSA

Serum albumin acts as a high-capacity carrier protein that reversibly binds a wide variety of drugs at specific hydrophobic pockets, primarily Sudlow's Site I and Site II. This binding regulates the free plasma concentration of drugs, protects them from rapid metabolism or excretion, and extends their biological half-life [3][4].