Plasma proteins and tissue proteins (N/A)

Plasma proteins and tissue proteins encompass a vast and heterogeneous group of molecules that are fundamental to physiological homeostasis and drug disposition. Plasma proteins, most notably albumin and alpha-1-acid glycoprotein, act as the primary transport vehicles for hormones, fatty acids, and pharmacological agents within the circulatory system (StatPearls: Albumin, 2023). Tissue proteins, including those found in the extracellular matrix and within specific organs, contribute to structural integrity and can serve as significant reservoirs for drugs, influencing their volume of distribution (Merck Manual: Drug Distribution). In pharmacology, these proteins are typically viewed as pharmacokinetic determinants rather than primary therapeutic targets; the degree of protein binding dictates the free or active concentration of a drug (PubMed: PMID 11510333). Alterations in the levels or binding capacity of these proteins, often seen in hepatic or renal disease, can lead to significant changes in drug efficacy and toxicity profiles (NIH: Liver Disease and Drug Metabolism). Displacement of a drug from these proteins by another agent can lead to transient increases in free drug concentration, potentially causing adverse effects (StatPearls: Drug-Drug Interactions). While specific proteins within this category, such as thrombin or various receptors, are targets, the collective group is primarily a pharmacokinetic sink. Monitoring levels of these proteins is essential in clinical settings to adjust dosing for drugs with narrow therapeutic windows.

Other names

Serum proteinsCirculating proteinsCellular proteinsExtracellular matrix proteinsBlood proteins

Non-specific binding and sequestration affecting drug pharmacokinetics, distribution, and bioavailability.