Hydroxyapatite crystal surface (HAP)

Hydroxyapatite is the primary inorganic constituent of vertebrate bone and teeth, providing structural rigidity and serving as a reservoir for calcium and phosphate ions (Source: PubChem, CID 14781). In pharmacology, the hydroxyapatite crystal surface acts as a specific target for bone-seeking agents, most notably bisphosphonates, which bind with high affinity to the calcium ions exposed on the crystal lattice (Source: StatPearls, Bisphosphonates). This binding allows for the localized delivery of therapeutic agents to sites of active bone remodeling, where they inhibit osteoclast-mediated bone resorption (Source: PubMed, PMID 11496237). Beyond osteoporosis and metabolic bone diseases, the hydroxyapatite surface is utilized in diagnostic imaging, such as bone scans using Technetium-99m, and as a scaffold in regenerative medicine (Source: Wikipedia, Hydroxyapatite). Its unique physicochemical properties, including ion-exchange capacity and surface charge, dictate its interaction with proteins and drugs in the bone microenvironment (Source: NIH, Bone Structure and Function).

Other names

HydroxylapatiteBone mineralCalcium apatiteHApCalcium phosphate hydroxyapatite

High-affinity adsorption to the mineral surface via chelation of calcium ions, leading to inhibition of crystal dissolution and localization of drugs to bone.