The pharmacokinetics and tissue penetration of gemifloxacin were determined during a 24 h period following oral administration of a single 320 mg dose to each of 10 healthy male volunteers. Concentrations of the drug in plasma, inflammatory blister fluid and urine were determined using a microbial assay. A peak plasma concentration (mean +/- S.D.) of 2.33 +/- 0.5 mg/L was reached at 1.20 +/- 0.4 h. Mean penetration into inflammatory fluid was 61.19 +/- 10.4%. A peak concentration of 0.74 +/- 0.3 mg/L was reached in the inflammatory fluid at a mean time of 3.40 +/- 1.7 h. The mean elimination half-life from serum and inflammatory fluid was 5.94 +/- 0.4 and 6.27 +/- 2.4 h, respectively. Urinary excretion of the drug at 24 h post-dose was 36.11% of the total given. These results demonstrate that gemifloxacin penetrates into the site of inflammation and reaches sufficient concentrations to inhibit many pathogens.