ANTIBIOTIC IN-VIVO IN-VITRO RELEASE, HISTOCOMPATIBILITY AND BIODEGRADATION OF GENTAMICIN IMPLANTS BASED ON LACTIC-ACID POLYMERS AND COPOLYMERS

Biodegradable implants containing 10 mg of gentamicin each were prepar ed by compressing the polymer-drug mixture. The liberation of gentamic in from the implants and the biodegradation of the implants were inves tigated by following in vitro and in vivo experiments. Implants based on pure poly(L-lactic acid) (L-PLA) released the incorporated antibiot ic throughout 30 days with a decreasing delivery rate. During the firs t 24 h L-PLA implants released a total amount of 3600 mu g gentamicin. Within 14 days the release rate had decreased to about 12 mu g/day. T he release profile of implants based on DL-lactic acid-glycolic acid c opolymer (RG 502) was completely different. About 1900 mu g were relea sed from the copolymer implants during the first 24 h. Release rate de creased to a value of about 3 mu g/day 15 days after implantation. In a second phase, starting 20 days after implantation, drug delivery inc reased again to reach values of about 100 mu g/day at the end of the e xperiment, i.e. 28 days after implantation. Very good tissue compatibi lity arises from the absence of inflammatory reactions throughout the entire time of implantation as shown by microscopy examinations. The d eveloped implants based on biodegradable polymers are suited for the t reatment of acute and chronic bone and tissue infections due to their specific release profiles, their excellent histocompatibility and thei r biodegradability.