ANTIBIOTIC-LOADED PLASTER OF PARIS IMPLANTS COATED WITH POLYLACTIDE-CO-GLYCOLIDE AS A CONTROLLED-RELEASE DELIVERY SYSTEM FOR THE TREATMENT OF BONE-INFECTIONS

Plaster of Paris implants containing vancomycin (60 mg/g of carrier) w ere prepared in order to be used as local delivery system for the trea tment of bone infections. The regulation of the release rate was perfo rmed by coating the carrier with a polylactide-co-glycolide polymer co mposed by 10% (w/w) polyglycolic acid and 90% (w/w) racemic poly (D,L- lactic acid). The release of the antibiotic from the biodegradable mat rix was evaluated in vitro. From this investigation, it is clear that the drug elution depends on the coating depth. After a burst effect oc curring on the first day of the experiment, therapeutic concentrations were measured during one week when uncoated implants were used. The c oating allowed decrease of the burst effect and extended efficient rel ease to more than five weeks when the implants were embedded with six layers (162 mu m) of PLA(45)GA(10). This delivery system was implanted into the femoral condyle of rabbits. It was shown that the in vivo re lease was also closely regulated by the coating depth. In all bone tis sues (bone marrow and cortical bone) surrounding the pellets, the drug concentration exceeded the Minimum Inhibitory Concentration for the c ommon causative organisms of bone infections (Staphylococcus aureus) f or at least four weeks without inducing serum toxic levels. Due to its cheapness, facility of use and sterilization, biocompatibility and bi odegradability, plaster of Paris coated with PLA(45)GA(10) polymer giv ing a controlled release of vancomycin appears to be a promising susta ined release delivery system of antibiotics for the treatment of bone and joint infections.