Development of a biodegradable antibiotic delivery system

Antibiotic beads have been used as a drug delivery system for the treatment of various surgical infections. In this study, the copolymer 50:50 poly(DL -lactide):co-glycolide was mixed with vancomycin powder and hot compressing molded at 55 degrees C to form five types of biodegradable antibiotic bead s. The beads were placed in 1 mL of phosphate buffered saline and incubated at 37 degrees C, The phosphate buffered saline was changed daily, and the removed buffer solutions were stored at -70 degrees C until the antibiotic concentration in each sample was determined by high performance liquid chro matography system assay. The concentration of vancomycin in each sample was well above the breakpoint sensitivity concentration (the antibiotic concen tration at the transition point between bacterial killing and resistance to the antibiotic) for more than 32 days,The release was most marked during t he first 38 hours. All copolymer 50:50 poly(DL-lactide):co-glycolide biodeg radable beads released high concentrations of the antibiotics in vitro for the time needed to treat bone infections (4 to 6 weeks), The diameter of th e sample inhibition zone ranged from 6.5 mm to 10 mm, and the relative acti vity of vancomycin ranged from 12.5% to 100%. Copolymers with low heat of f ormation temperatures are required for making a controlled release system t o prevent antibiotic decomposition, which occurs when using the hot compres sing molded method, The rate and duration of release from the antibiotic be ads can be adjusted by varying the diameter of the beads. This offers a con venient method to adjust the release rate to meet the specific antibiotic r equirements for different patients.