Rifampicin pharmacokinetics with and without ciprofloxacin.

We investigated the effect of ciprofloxacin on rifampicin pharmacokinetics in five healthy subjects. Each subject received 600 mg rifampicin with 350 mL of water, and in the second phase, each subject received 600 mg rifampicin plus 500 mg ciprofloxacin with 350 mL of water. In each of the two phases, plasma rifampicin levels were measured from 1 to 24 hours. Treatment with ciprofloxacin significantly increased the half-life and also significantly decreased the maximum peak concentration of rifampicin. Area under the curve time for peak plasma concentration and volume of distribution were not significantly affected. In this study, we found that ciprofloxacin increases the half-life and reduces the maximum concentration of rifampicin in humans.