Controlled release systems based on poly(lactic acid). An in vitro and in vivo study

A new biodegradable delivery system based on poly(lactic acid) has been for mulated, with potential applications in sustained antibiotic release agains t bone infection. The in vitro release of a new quinolone (pefloxacin) from low molecular weight poly(D,L-lactic acid) (Mw = 2 x 10(3)) lasted for 56 d whereas the in vivo delivery lasted 33 d. In both cases, the release rate is controlled by the drug diffusion and the polymer degradation, which see ms to be the predominant factor. For the release experiments, discs were pr epared from poly (D,L-lactide) (Mw = 2 x 10(4)) with drug loadings of 2% an d 10% w/w. It was concluded that pefloxacin concentration remains higher th an the Minimum Inhibitory Concentration (MIC) against the major causative b acteria of bone infection. The results indicate that the two different type s of poly(lactic acid) can be used effectively in an implantable antibiotic release system. (C) 2000 Kluwer Academic Publishers.