Alpha-1-acid glycoprotein (AAG) (AAG)

Alpha-1-acid glycoprotein (AAG), also known as orosomucoid, is a 41-43 kDa plasma protein primarily synthesized by hepatocytes and belonging to the lipocalin family (UniProt, 2024). It serves as a major carrier for basic (cationic) and lipophilic drugs, including local anesthetics such as lidocaine, bupivacaine, and ropivacaine (StatPearls, 2023). As an acute-phase reactant, AAG concentrations can increase several-fold in response to inflammation, trauma, or malignancy, which significantly alters the free fraction of drugs in the bloodstream (PubMed, 2021). Conversely, neonates and patients with severe liver disease often exhibit low AAG levels, increasing their susceptibility to local anesthetic systemic toxicity (LAST) due to a higher proportion of unbound, active drug (NIH, 2022). Understanding AAG binding is essential for clinical dosing, as it acts as a buffer that modulates the pharmacodynamics and safety of many critical care medications.

Other names

OrosomucoidORMORM1ORM2Alpha-1-acid glycoprotein 1

High-affinity, low-capacity binding of basic (cationic) and lipophilic drugs in plasma, which limits the free fraction available for tissue distribution and pharmacological effect (PubMed, 2021).