Drug hydroxyapatite

Antibiotic-loaded composites of poly(DL-lactic acid) and hydroxyapatite have been studied as a filler in the repair of bone defects (106). The drug dideoxykanamycin was formulated at 20% by weight in a 50 50 PL A/hydroxyapatite composite. Cyclindrical composites were implanted into the penetrated tibeas of rats. Antibiotic was present at the implantation site at least 8 weeks postimplantation. 

T., Katutani, Y., and Kitsugi, T., Release of antibiotics from composites of hydroxyapatite and poly(lactic acid), in Advances in Drug Delivery Systems (J. M. Anderson and S. W. Kim, eds.), Elsevier, New York, 1986, pp. 179-186. 

Polyphosphazenes are a relatively new class of biodegradable polymers. Their hydrolytic stability or instability is determined not by changes in the backbone structure but by changes in the side groups attached to an unconventional macromolecular backbone. Synthetic flexibility and versatile adaptability of polyphosphazenes make them unique for drug delivery applications. For example, Veronese et al.18 prepared polyphos-phazene microspheres with phenylalanine ethyl ester as a phosphorous substituent and loaded it with succinylsulphathiazole or naproxen. The kinetics of release from these matrices were very convenient in yielding local concentrations of the two drugs that are useful per se or when mixed with hydroxyapatite for better bone formation. Polyphosphazene matrices are also considered as potential vehicles for the delivery of proteins and vaccines.19... 

Vladimir, S. K., Serquei. M. D. and Elena, V. K. (2002). A method to fabricate porous spherical hydroxyapatite granules intended for time controlled drug release. Biomaterials, 23 3449-3454. 

Several other biodegradable, biocompatible, injectable polymers are being investigated for drug delivery systems. They include polyvinyl alcohol, block copolymer of PLA-PEG, polycyanoacrylate, polyanhydrides, cellulose, alginate, collagen, gelatin, albumin, starches, dextrans, hyaluronic acid and its derivatives, and hydroxyapatite. ... 

Calcium phosphate A family of calcium phosphate ceramics including aluminum calcium phosphate, ferric calcium phosphate, hydroxyapatite and tricalcium phosphate (TCP), and zinc calcium phosphate which are used to substitute or augment bony structures and deliver drugs. Glass-ceramics A glass crystallized by heat treatment. Some of those have the ability to form chemical bonds with hard and soft tissues. Bioglass and Ceravital are well known examples. 

Y. Mizushima, T. Ikoma, J. Tanaka, K. Hoshi, T. Ishihara, Y. Ogawa, and A. Ueno, Injectable porous hydroxyapatite microparticles as a new carrier for protein and lipophilic drugs, J. Contr. Rel, 110(2), 261U265 (2006). 

Zhang, J. Wang, Q. Wang, A. In situ generation of sodium alginate/hydroxyapatite nanocomposite beads as drug-controlled release matrices. Acta. Biomater. 2010, 6 (2), 445-454. 

Figure 35.8 shows lithium calcium borate (LCB) glass microspheres that were spheroidizedby passing them through a high-temperature flame. A similar process is used to make the smaller YAS microspheres. The LCB microspheres are subsequently converted into hollow hydroxyapatite microspheres that have potential application in drug delivery. 

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