Amorphous calcium phosphate (ACP) (ACP)

Amorphous calcium phosphate (ACP) is a non-crystalline, metastable mineral phase that serves as a critical precursor to the formation of crystalline hydroxyapatite in biological systems (Dorozhkin, S. V., 2010, Acta Biomaterialia). While it plays a physiological role in bone and tooth mineralization, its accumulation in soft tissues constitutes pathological calcium deposits, which are central to the pathogenesis of vascular calcification, atherosclerosis, and nephrolithiasis (Giachelli, C. M., 2004, Journal of the American Society of Nephrology). In these disease states, ACP precipitates within the extracellular matrix of blood vessels or organs, leading to structural stiffness, reduced compliance, and functional impairment (Boskey, A. L., 1997, Osteoporosis International). Therapeutic strategies targeting ACP focus on inhibiting its transition to more stable crystalline forms or promoting the dissolution of existing deposits. Drugs such as bisphosphonates (e.g., Etidronate) and pyrophosphate analogs bind to the surface of these mineral clusters to prevent further growth, while chelating agents like sodium thiosulfate or EDTA work by increasing the solubility of calcium or sequestering calcium ions (Fleisch, H., 1991, Trends in Pharmacological Sciences; O'Neill, W. C., 2007, Seminars in Dialysis). Managing these deposits is particularly critical in patients with chronic kidney disease to mitigate high cardiovascular mortality rates associated with medial calcification.

Other names

Non-crystalline calcium phosphateVitrified calcium phosphateEctopic calcium depositsPathological calcification mineralCalcium phosphate clusters

Inhibition of crystal nucleation and growth, stabilization of the amorphous phase to prevent transformation into hydroxyapatite, and chelation of calcium ions to increase mineral solubility.