The Research Of Hollow Micro-hydroxyapatite Loaded With Alendronate As Drug Slow-release System

In the process of building a local drug slow-release system, drug release carrier isan important part in the drug release system, which works as a main factor onincreasing drug release efficacy. The physical and chemical factors of drug carrier,such as pore structure, chemical structure, determine whether the drug can achieveideal slow-release effect. Therefore, the innovation on new way to construct carriermaterials is a research hotspot in recent years.Carbonated hydroxyapatite (CHA), the major inorganic constituent of naturalbones and teeth, has long been known for its excellent biocompatibility, bioactivity,bioconductivity and nontoxicity. Over the past few decades, there has beenconsiderable interest in the development of hollow hydroxyapatite devices for drugdelivery. The kinetics of drug release depended on both porosity degree andcalcium-to-phosphor ratio of drug carriers. Three-dimensional (3D) poroushydroxyapatite, in particular hollow nanostructure, owing to their large surface areaand good biocompatibility, have been attracted much attention in drug delivery system,which ensure a predictable therapeutic response, an advanced efficacy and safety oflocal delivery.Bisphosphonates have been used industrially as corrosion inhibitors andcomplexing agents since100years before. In the late1960s, Fleisch et al. recognizedthese materials have potential in bone diseases treatment. Until now, they havenotably been investigated for the treatment of bone diseases like Paget’s disease,osteoporosis, bone metastases, malignancy-associated hypercalcemia, and as targetingagents for colloids and drugs. Bisphosphonates can bind to hydroxyapatite crystals in a mineralized bone matrix and increase bone resistance against osteoclasts. Therelative contributions of these properties differ among individual bisphosphonates,and can help determine their clinical behavior and effectiveness. In addition, somekind of bisphosphonates, such as alendronate with low concentration, have beenproved that could promote osteogenesis and increase bone mineral density. Because oftheir well-recognized therapeutic benefits, bisphosphonates have currently beingevaluated in an array of applications in oral clinical. Herero, The Research of hollowmicro-hydroxyapatite loaded with alendronate could devote for the clinicalapplication on oral medicine.In this research, hollow carbonated hydroxyapatite (HCHA) microspheres wereprepared by reacting hollow calcium carbonate microspheres in Na2HPO4solution,and evaluated as a controlled delivery device for alendronate(AL). The biocompatibleHCHA microspheres, with a particle size of1~3μm, have high surface area (98.14m2/g) and high drug loading capacity(23.2%~40.79%). The sustained release of ALfrom HCHA microspheres was achieved over25days. The biocompatibility of thecomposite microsphere was assessed by examining the expression of ALP of stemcells from human exfoliated deciduous teeth. The results showed that the10-9mol/LAL underwith HA material composited can promote the ALP expression. TheseHCHA microspheres could provide a novel inorganic device for controlled localdelivery of drugs.