A biodegradable polymer of dl-dilactide that facilitates release of ciprofloxacin or pefloxacin at levels exceeding MICs for the causative microorganisms of chronic osteomyelitis is described. Duration and peak of release were found to depend on the molecular weight of the polymer. Its characteristics make it promising for treating chronic bone infections.

A new biodegradable delivery system based on low molecular weight poly(lactic acid) has been formulated, with potential application in the sustained antibiotic release against bone infection. The in vitro release of two new quinolones (ofloxacin and ciprofloxacin) from the biodegradable matrix showed that the delivery of ofloxacin from the matrix lasted fifty-six days, whereas that of ciprofloxacin lasted fifty-one days. In both cases, release is controlled by the drug diffusion and the matrix degradation, the latter being the most critical factor. The obtained concentration levels are well above the Minimum Inhibitory Concentration (MIC) against the major causative bacteria of osteomyelitis. This fact in combination with the good reproducibility of measurements indicated that the system studied could be of value for the preparation of implantable controlled release systems for treatment of diseases in the bone system.

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