Gentamicin may have an adverse effect on osteogenesis

Objective: To investigate the toxic effect of gentamicin at the high concentrations that can be achieved by local administration in the management of bone infection. Design: Randomized, prospective study in cultured cells, with drug exposure duration of 4 days. Setting: Cell culture in Dulbecco's modification of Eagle's minimal essential medium with supplements at 37degreesC in air:CO, (v:v, 95:5). Materials: Human osteoblastlike cells derived from cancellous bone collected from four adult patients without systemic disease during total hip replacement were cultured in antibiotic-free medium for 4 weeks. Intervention: The cultured cells were exposed to media containing various concentrations of gentamicin (0-1000 mug/mL) for 4 days. Main Outcome Measurements: Alkaline phosphatase activity, total DNA, and H-3-thymidine incorporation. Result: Alkaline phosphatase activity was significantly decreased (p < 0.05) in all of the cultures at gentamicin concentrations of 100 mug/mL and above. H-3-thymidine incorporation was also decreased (p < 0.05) in three out of four cultures at 100 VLg/mL and above. Total DNA was significantly decreased (p < 0.05) at 700 mug/mL and above. Conclusion: Gentamicin, at high concentrations, as achieved following topical application, inhibits cell proliferation in vitro and, therefore, may be detrimental to the repair process in vivo.