Hydroxyapatite (HA)

Hydroxyapatite is a naturally occurring inorganic mineral form of calcium apatite with the chemical formula Ca10(PO4)6(OH)2, and it is the primary mineral component of bone and tooth enamel in vertebrates[3][4][6]. Hydroxyapatite crystals interspersed in the collagen matrix provide the rigidity and structural strength essential to bone and teeth[3][4][6]. In the body, hydroxyapatite formation (biomineralization) is a tightly regulated process involving matrix vesicles released from osteoblasts, serving as nucleation sites for crystal growth, and regulated by proteins and local ionic environments[1][5]. Hydroxyapatite formation as a process is important in both normal bone remodeling and repair, and it is also a target for synthetic biomaterials used in orthopedics and dentistry to stimulate bone regeneration through its osteoinductive and osteoconductive properties[4][5][7]. Abnormal deposition can lead to pathological calcifications such as calcific tendinitis or kidney stones[3][4].\n\nNote:\n- "Hydroxyapatite formation" describes a *biomineralization process*, not a molecular entity or specific drug target. Thus, it is not a receptor, enzyme, transporter, or typical druggable target.\n- "Hydroxyapatite" (the mineral) is not typically the target of drugs; rather, its formation is influenced by physiological and pathological conditions. In contrast, drugs may target upstream regulators of mineralization such as enzymes and signaling proteins in bone metabolism pathways[2][4].\n- Common confusion may arise when searching for targets related to bone formation; key molecular targets include proteins such as RANKL (receptor activator of nuclear factor kappa-B ligand), OPG (osteoprotegerin), and others involved in osteoblast/osteoclast regulation, not hydroxyapatite itself[2].

Other names

Calcium hydroxyapatiteHAPCa10(PO4)6(OH)2