1Comparative Orthopaedics Laboratory, Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY2Anatomy, Physiological Sciences and Radiology, North Carolina State University, Raleigh, NC3Large Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon SK, Canada4Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY
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Objective:To determine in vitro elution characteristics of amikacin and ticarcillin from fiber reinforced calcium phosphate beads (FRCP).Sample Population:Experimental.Methods:FRCP beads with water (A), amikacin (B), ticarcillin/clavulanate (C), or both amikacin and ticarcillin/clavulanate (D) were bathed in Symbol. mL phosphate-buffered saline (PBS) at 37°C, 5% CO2 and 95% room air. PBS was sampled (eluent) and beads were placed in fresh PBS at time points 1 and 8 hours and 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 18, 21, 25, 28, 35, 42, 49, and 56 days. Antibiotic concentration and antimicrobial activity of eluent against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae were determined.Results:Both antibiotics eluted in a bimodal pattern. Beads with a single antibiotic eluted 20.8 ± 2.5% of amikacin and 29.5 ± 0.8% of ticarcillin over 56 days. Coelution of the antibiotics resulted in a lower proportion (AUC0–∞) of antibiotics eluted for both amikacin (9.5 ± 0.2%) and ticarcillin (21.7 ± 0.09%). Bioassay of antimicrobial activity of the eluent (t=1, 8, and 24 hours) established reduced antimicrobial activity of amikacin from combination beads (D).Conclusions:FRCP beads with amikacin or ticarcillin/clavulanate, but not the combination, are suitable carriers for wound implantation.Clinical Relevance:Duration before complete resorption of FRCP beads in vivo should be determined before clinical use as a resorbable depot. The results of this study underscore the importance of testing drug combinations, despite success of the combination systemically, before their use in local applications.