Penetration of moxifloxacin into bone in patients undergoing total knee arthroplasty

OBJECTIVES: To investigate plasma and bone moxifloxacin concentrations following oral administration of a single or double dose of the drug, in order to consider its potential role in the treatment of osteomyelitis. PATIENTS AND METHODS: Thirty consecutive patients undergoing total knee arthroplasty were recruited. Three groups, of ten patients each, were formed: group A received moxifloxacin 400 mg orally 2 h (range 1.5-2.5) preoperatively, group B received moxifloxacin 400 mg orally 4 h (range 3.5-4.5) preoperatively and group C received moxifloxacin 400 mg orally 14 h preoperatively, followed by a second dose 2 h (range 1.5-2.5) preoperatively. During surgery, at the time of bone removal, a blood sample and aliquots of cortical and cancellous bone were collected and moxifloxacin concentrations were measured by HPLC. RESULTS: Mean plasma, cancellous bone and cortical bone concentrations were, respectively: 3.45, 1.89 and 1.43 mg/L for group A; 3.73, 1.81 and 1.56 mg/L for group B; and 6.26, 2.97 and 2.54 mg/L for group C. CONCLUSIONS: These data show a good penetration of moxifloxacin into both cancellous and cortical bone, with concentrations, after double dosing, exceeding the MIC90 for most pathogens involved in osteomyelitis and the clinic susceptibility breakpoint for Mycobacterium tuberculosis.