Evaluation of 90:10 poly(D,L-lactide-co-glycolide) microspheres containing norethisterone: drug release and biodegradation

Salicylic acid-derived poly(anhydride-esters) inhibit bone resorption and formationin vivo

The objective of this study was to investigate the effects of a novel polymer that biodegrades into salicylic acid (SA) on the healing of critical sized long bone defects. Microspheres of the homopolymer, or a copolymer containing 50% less of the SA, were packed into 5-mm mid-diaphyseal defects in rat femurs. Control animals received collagen sponge implants. After 4 and 8 weeks of implantation, bone healing was evaluated using microradiography and quantitative histomorphometry. Four weeks postsurgery, significantly less new bone was formed in both of the polymer groups (p<0.038). Reduced bone loss was also noted with the polymers at this time, although it was not statistically significant. However, at 8 weeks postsurgery, a statistically significant reduction in bone loss was observed in both of the polymer groups compared with controls (p<0.0072). Both polymers seemed to elicit identical tissue responses because there were no differences detected between the homopolymer and copolymer materials at either time point. These results indicate that locally released SA can significantly reduce both bone loss and bone formation in this animal model.

Preparation of polylactic acid microcapsules containing ciprofloxacin

Microcapsules have been used as drug delivery systems in the pharmaceutical field for sustained or controlled release of drug, and for artificial cells and organs. Biodegradable polymers, especially polylactic acid, have been widely used in this field. In this study, an attempt was made to develop a new method to prepare polylactic acid microcapsules for drug delivery. The biodegradable polylactic acid microcapsules were made by the phase separation process: two types of polylactic acid, poly[(D,L)lactic acid] and poly[(L)lactic acid] were combined as the membrane material. Because of the difference of the crystal properties of the two polymers, the aggregation which happens frequently in the phase separation process was prevented. As a model drug, Ciprofloxacin was encapsulated in the polylactic acid microcapsules.