Levofloxacin does not alter cyclosporine disposition

Certain fluoroquinolones have been shown to elevate the serum concentrations of the immunosuppressant cyclosporine. It is thus important to investigate the potential interaction between levofloxacin, a new fluoroquinolone antimicrobial agent, and the pharmacokinetics of cyclosporine. Twelve healthy subjects (6 men, 6 women) were enrolled in and completed a placebo-controlled, randomized, double-blind, two-phase crossover study. Subjects were given a single oral 10-mg/kg dose of cyclosporine solution during multiple-dose twice-daily oral treatment with placebo or 500 mg of levofloxacin. Blood cyclosporine concentrations were measured for 48 hours after each cyclosporine dose for pharmacokinetic evaluation. Cyclosporine pharmacokinetic parameters were comparable and not significantly different in the absence and presence of levofloxacin. Results of this study suggest that a clinically important pharmacokinetic interaction between levofloxacin and cyclosporine is unlikely to occur during concurrent therapy.