The effect of ciprofloxacin and pefloxacin on bone marrow engraftment in the spleen of mice.

In order to investigate the in-vivo effect of ciprofloxacin and pefloxacin on bone marrow engraftment in mice, irradiated mice were transplanted with bone marrow graft (5 x 10(5) cells/mouse) obtained from syngeneic mice. Three groups of mice (30 mice in each) received a bone marrow graft incubated for 1 h with ciprofloxacin at concentrations of 0.5, 5 and 50 mg/l. Six additional groups (30 mice in each) were treated twice daily after transplantation with intra-peritoneal injections of ciprofloxacin in dosages of 25, 50 and 100 mg/kg/24 h or pefloxacin in dosages of 10 and 100 mg/kg/24 h. Evaluation of bone marrow engraftment was performed in animals injected with I125 Iodo-deoxyuridine (0.5 mu Ci/mouse) by radioactive counting of the entire spleen and also by counting visible colonies on the spleen surface. The results of this study demonstrate a statistically significant depression of bone marrow graft uptake (P less than 0.05, student t-test) in mice treated twice daily with ciprofloxacin in dosage of 100 mg/kg/24 h, a concentration far beyond the therapeutic range.