Novel polymers incorporate drug

A monomer prepared from a drug that is used for treating bone diseases could serve as a useful building block for synthesizing new therapeutic polymeric materials. Bing Xu and coworkers at Hong Kong University of Science & Technology prepared a monomer containing pamidronate-a bisphosphonate compound that chelates calcium ions and is used clinically to treat tumor-induced hypercalcemia (high levels of calcium in the blood), postmenopausal osteoporosis, and bone metastases associated with breast cancer (Chem. Commun. 2006, 2795). The researchers used the monomer, N-acryl pamidronate, to synthesize poly(pamidronate). This polymer should effectively raise the local concentration of the drug in the body and therefore maximize its therapeutic effect, they say. The team also copolymerized the monomer with N-isopropylacrylamide to form the cross-linked hydrogel poly(N-acryl pamidronate-co-N-isopropylacrylamide). The hydrogel copolymer acts as a scaffold for the mineralization of hydroxyapatite, a calcium phosphate compound found in bone and teeth. The hydrogel-hydroxyapatite composite may prove to be a suitable biomaterial for mimicking natural bone, the authors suggest.