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Enhancing Drug Release From Antibiotic-loaded Bone Cement Using Porogens

Objective: To evaluate whether the addition of porogens to polymethyl methacrylate (PMMA) enhances the antibiotic elution rate from antibiotic-loaded bone cement.Methods: Two porogens, gelatin sponge (Spongostan, Ferrosan Medical Devices) and ceramic granules (Bicera, Wiltrom), were added to liquid gentamicin-loaded PMMA at increasing concentrations. Porosity was analyzed using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy. Young’s modulus and drug elution were also measured. The gentamicin content of the eluents was evaluated by o-phthaldialdehyde (OPA) assay on days 1, 2, 5, 7, 10, and 14.Results: After day 5, the drug-releasing rate of Spongostan was significantly higher than that of Bicera in the order G3 > G2 > T3 > G1 > T2 > T1 > bone cement, where G represents the concentration of Spongostan and T represents the concentration of Bicera. The addition of Bicera and Spongostan increased the drug-releasing efficiency of PMMA by 3.75-fold and 5.65-fold, respectively. Spongostan also resulted in larger pores (ie, 70 to approximately 200 &mgr;m) compared with Bicera (5 to 10 &mgr;m) but reduced biomechanical strength.Conclusion: Both gelatin sponge and ceramic granules improved the local antibiotic elution rate, although the drug-releasing rate of Spongostan was significantly higher than that of Bicera.