Drug-Loading Calcium Phosphate Cements For Medical Applications

Calcium phosphate cements (CPCs) are uniquely promising drug carriers for orthopedic applications because of their room-temperature setting property and injectability. This chapter reviews the basics of CPCs, techniques used for preparing drug-loaded CPCs and composites, effects of drug incorporation on the physicochemical characteristics (i.e., strength, handling properties) of the cement, the drug release behaviors of drug-loaded CPCs, and medical applications of CPCs for the delivery of a variety of drugs. It becomes clear that, with from simple to latest techniques (e.g., mixing, 3D freedom fabrication), CPCs incorporating a large number of drugs have been developed including antibiotics, analgesics, anti-osteoporotic agents, anti-inflammatory compounds, and anticancer drugs. Composites with more advanced structures (e.g., polymer microspheres-in-cement design) have also been widely investigated to modulate drug release profiles and cement degradation. Additionally, although drug release almost routinely follows Higuchi's diffusion-controlled model, other situations exist and innovations in material design can open new possibilities in controlling the rate of drug release. Finally, we suggest that development of smarter and multifunctional CPC release systems, such as sequential release CPCs for meeting the requirements of each stage of bone healing, may be a promising direction for future research.