Moxifloxacin is a fourth generation synthetic fluoroquinolone antibacterial agent. Moxifloxacin is a broad-spectrum antibiotic that is active against both Gram-positive and Gram-negative bacteria. It functions by inhibiting DNA gyrase, a type II topoisomerase and topoisomerase IV, which is an enzyme necessary to separate bacterial DNA, thereby inhibiting cell replication. The moxifloxacin concentrations in the aqueous humor following oral administration exceeded the minimum inhibitory concentration for 90% of the bacteria involved in ocular infection. The mean maximum concentrations of moxifloxacin in plasma (C max) ranged from 0.29 mg/liter (50-mg dose) to 4.73 mg/liter (800-mg dose) and were reached 0.5 to 4 h following drug administration.