Elution profiles of cefazolin from PMMA and calcium sulfate beads prepared from commercial cefazolin formulations

Antibiotic beads have become popular for the treatment of local bacterial infections. The preparation of antibiotic beads from commercial pharmaceutical antibiotics is a convenient method in clinic. The elution characteristics of cefazolin from polymethylmethacrylate (PMMA) (SmartSet HV, Depuy I and Cemfix 3) beads and calcium sulfate beads were studied. Commercial cefazolin formulation was incorporated in PMMA or calcium sulfate at 1 g cefazolin/10 g of matrix substances to form beads. The concentrations of eluted cefazolin during 15 days were greater than MIC for Staphylococcus aureus (ATCC 25923). The eluted cefazolin concentrations were in the range of 3.6 ± 1.2 to 4.6 ± 0.4 mg for PMMA beads and 15.4 ± 1.7 mg for calcium sulfate beads. The accumulated eluted cefazolin from PMMA beads and calcium sulfate beads for 15 days were 34.41 ± 3.93 to 38.67 ± 3.04% and 95.94 ± 3.93%, respectively. The various storage conditions; at room temperature or 4°C, with or without light-protection, for 6 months had little effects on the amounts of eluted cefazolin. The results showed both in-housed cefazolin-PMMA beads and cefazolin-calcium sulfate beads could be the effective tools for the treatment of local bacterial infections.