Comparative elution of moxifloxacin from Norian skeletal repair system and acrylic bone cement: an in vitro study

The objective of this study was to evaluate the efficacy of Norian skeletal repair system (SRS), a novel biodegradable and injectable form of calcium phosphate cement with a composition similar to that of cancellous bone, as a carrier for moxifloxacin, which is the most potent quinolone agent against staphylococci and Enterobacteriaceae. Norian SRS was mixed with moxifloxacin at a ratio of ca. 100:3 at room temperature and solidified in the bottom of a cylindrical vial. The same procedure was followed for acrylic bone cement. A total of five vials were prepared per system. Mueller-Hinton broth was placed over the free surface of both systems and the vials were transferred to a 37 degrees C incubator. The broth was replaced daily until visual degradation of both systems. Moxifloxacin was measured in aliquots of broth after passage through a high-performance liquid chromatography system. Optical degradation of both systems occurred after 450 days. Until Day 17, concentrations eluted from both systems were similar. After Day 18 until degradation, concentrations eluted by Norian SRS were statistically higher than those eluted by acrylic bone cement and ranged between 100 mg/L and 800 mg/L. The mean area under the concentration-time curve (AUC) over 450 days of sampling was 241 935.0 mg/L day for Norian SRS and 18 300.0 mg/L day for the acrylic bone cement system (P=0.043). Norian SRS is a novel biodegradable system providing excellent strength and mineralisation to bone. It was shown that this system allows in vitro elution of moxifloxacin at significant concentrations, making it a promising candidate for the therapy of chronic osteomyelitis.