Ciprofloxacin is a fluoroquinolone antibiotic that is widely used as an antimicrobial and immunomodulatory agent. Its range of activity includes most strains of bacterial pathogens capable of inducing respiratory, urinary tract, gastrointestinal, and abdominal infections. It functions by inhibiting DNA gyrase (a type II topoisomerase) and topoisomerase IV, the enzymes responsible for negative supercoiling of chromosomes and DNA strand separation, thus blocking initiation of bacterial replication. Most recently ciprofloxacin has been used in the management of postexposure inhalational anthrax and radiation combined injury resulting from nuclear disasters.