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 °C. The ALBC efficacies against prevalent bone infection bacteria, S. aureus, E. coli, and P. 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 and S. aureus was 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.

Evaluation of the Effect of Ciprofloxacin and Vancomycin on Mechanical Properties of PMMA Cement; a Preliminary Study on Molecular Weight.

Antibiotic-loaded bone cement (ALBC) is commonly used in joint replacement therapy for prevention and treatment of bone infection and mechanical properties of the cement is still an important issue. The effects of ciprofloxacin and vancomycin was investigated on mechanical characterization of PMMA bone cement. Different properties of cement containing (0, 2.5, 5 and 10% W/W) antibiotics, including compressive and bending properties, microstructural, porosity and density were evaluated. Both antibiotics significantly reduced the density values and mechanical properties (compressive and flexural strength and modulus) in all groups in comparison to control over first two weeks (p < 0.05). This reduction was due to increased porosity upon antibiotic addition (3.05 and 3.67% for ciprofloxacin and vancomycin, respectively) in comparison to control (2.08%) (p < 0.001) and exposure to aqueous medium. Vancomycin as antibiotic with higher molecular weight (MW = 1485) had significant effect on compressive strength reduction of the cement at high amount compared to ciprofloxacin (MW = 367) (P < 0.01), there was no difference between two antibiotics at lower concentrations (P > 0.05). The effect of antibiotic loading is both molecular weight and drug content dependent. The time is also an important parameter and the second week is the probably optimum time to study mechanical behavior of ALBC.