Pharmacokinetic profiles of ciprofloxacin after single intravenous and oral doses

Ciprofloxacin was administered to 12 healthy male volunteers at doses of 300 and 400 mg intravenously (i.v.) and 500 and 750 mg orally in a randomized, double-blind, single-dose, four-period crossover study. On each treatment day, each subject received both oral and i.v. formulations, one of which was a placebo. Blood and urine samples were obtained through 24 h postdose. By each dosing route, the pharmacokinetic profiles were dose proportional. The 400-mg i.v. dose was equivalent to the 500-mg oral dose with respect to the area under the concentration-time curve and was equivalent to the 750-mg oral dose with respect to the maximum concentration of ciprofloxacin in serum. The oral bioavailability was 78.0%. The steady-state volume of distribution averaged 178 liters, and the terminal half-life in serum after i.v. dosing was approximately 4.3 h. Renal clearance accounted for approximately 60% of total body clearance. No significant adverse events were associated with either route of administration.