Effect of dose size on bioavailability of ciprofloxacin

We evaluated the bioavailability of ciprofloxacin at two dose sizes in eight healthy volunteers. Each volunteer was given 200 mg of ciprofloxacin both orally and intravenously in a randomized crossover fashion and 750 mg orally. Bioavailability at the two doses was similar: 69 and 69.1% for the 200- and 750-mg doses, respectively. However, the bioavailability observed with the 750-mg dose was significantly more variable than that observed with the 200-mg dose. Between 375 and 700 mg of ciprofloxacin reached the systemic circulation after administration of the 750-mg dose, with no evidence of adverse reactions.