The influence of γ irradiation and ethylene oxide treatment on the release characteristics of biodegradable poly(lactide-co-glycolide) composites

This study evaluated the influence of γ irradiation and ethylene oxide sterilization on the release characteristics of vancomycin from biodegradable poly[(d,l)-lactide-co-glycolide] (PLGA) composite beads. Biodegradable composites incorporating vancomycin were prepared using a compression-sintering method. They were then subjected to various doses of γ irradiation and ethylene oxide treatment. After sterilization, the composites were placed in 3 ml of phosphate buffered saline and incubated at 37°C. An in-vitro elution method and a high-performance liquid chromatography (HPLC) were used to characterize the release rates of the antibiotics over a 30-day period. A bacterial inhibitory test was also employed to examine the bioactivity of released antibiotics. All sterilizations were found to result in a decrease of the crystallinity of the polymeric materials, as well as the total release period of antibiotics. The ethylene oxide treatment led to a significant change of the morphology of the composites. Furthermore, the results suggest that the biodegradable composites can release high concentrations of antibiotics (well above the minimum inhibitory concentration) in-vitro for up to 28 days after γ irradiation of less than 25 kGy.