Release behavior, mechanical properties, and antibacterial activity of ciprofloxacin-loaded acrylic bone cement: a mechanistic study

Objective To evaluate the effect of ciprofloxacin concentration and cement geometry on release, mechanical, and antibacterial properties of PMMA bone cement. Significance:Cements are used in different geometries and drug concentrations. These can affect cement strength, drug release behavior, and its antibacterial activity. Methods Antibiotic-loaded bone cement (ALBC) containing 2.5, 5.0, and 10.0 wt% ciprofloxacin were prepared as slab, rectangular prism and short cylinder. Drug release and compression strength of the cements were investigated for 28 days at 37 degrees C. The ALBC efficacies against prevalent bone infection bacteria,S. aureus,E. coli, andP. aeruginosa, were investigated. Drug determination was by HPLC. Results A two-stage behavior of fast release through dissolution/diffusion (stage A; <96 h) and 2-5 times slower Fickian diffusion (stage B; 96-672 h) was observed. Significant differences for release rate were observed among different geometries in the order of cylinder > prism > slab, in correlation with systems' thickness, indicating lower drug depletion in thicker systems. Release rates were proportional to concentration for 2.5 and 5% systems. At 10.0% loading, however, apparently interconnected channels and higher porosity reduced the diffusional resistance and provided higher release rates than what expected from concentration increment. Growth of Gram-negative bacteria andS. aureuswas inhibited at the lowest dose of drug over 1 and 48 h, respectively. ALBCs with 5.0 and 10.0% ciprofloxacin showed decrease of compression strength to below ISO standard. Conclusions Different properties of acrylic cements are affected by geometry and drug concentration and should be considered for optimized drug therapy.