Anionic serum and extracellular proteins (ASEP)

Anionic serum and extracellular proteins represent a broad class of negatively charged molecules, including human serum albumin and various components of the extracellular matrix, that play a critical role in the pharmacokinetics of cationic drugs. At physiological pH, these proteins carry a net negative charge, allowing them to interact electrostatically with polycationic compounds such as aminoglycoside antibiotics. This interaction is a primary determinant of the volume of distribution and the tissue-specific accumulation of these drugs, particularly in the kidneys and inner ear. While not a traditional signaling receptor, this 'target' group acts as a significant physiological sink and a mediator of drug-induced toxicities. In clinical practice, the binding of drugs to these proteins can influence both the therapeutic efficacy and the safety profile, as seen in the competitive binding and subsequent endocytosis that leads to aminoglycoside-induced nephrotoxicity.

Other names

Anionic serum proteinsExtracellular anionic sitesSerum albumin and anionic globulinsAnionic extracellular matrix components

Drugs, particularly polycationic aminoglycosides, bind electrostatically to these anionic proteins, which can lead to sequestration in the extracellular space or facilitate uptake into specific tissues like the renal proximal tubules via endocytosis.