Animals were challenged with a target dose of 200 LD50 of aerosolized B. anthracis spores.
Ciprofloxacin was administered via the IP route TID for 14 days post-challenge, starting 20 to 24 hours post-challenge, at dose levels of 5, 7.5, or 10 mg/kg. The animals were observed for morbidity and mortality and euthanized 21 days after the final ciprofloxacin treatment. Blood samples were collected prior to the anthrax challenge, 30 minutes after the morning ciprofloxacin injection on day 8 and 8 hours after the last treatment on day 15, to evaluate peaks and troughs of plasma ciprofloxacin levels among the groups. Peak ciprofloxacin concentrations were dose-dependent. The trough concentrations dropped slightly below the MIC50 of 64 ng/mL at all dose levels.