Ciprofloxacin does not impair the elimination of diazepam in humans

The pharmacokinetics of a single iv dose of 10 mg diazepam and the renal excretion of its metabolites resulting from N-demethylation and C-3-hydroxylation were investigated in 10 healthy volunteers when diazepam was administered alone and on day 3 of administration of the fluoroquinolone ciprofloxacin (500 mg twice per day). No significant changes in the diazepam half-life, its volume of distribution, the total body clearance, or the renal clearance were observed. In addition, the renal excretion of the metabolites desmethyldiazepam, 3-hydroxydiazepam (temazepam), and 3-hydroxydesmethyldiazepam (oxazepam) were not altered by ciprofloxacin co-medication. These data demonstrate that in a 500 mg twice per day oral dosage, ciprofloxacin does not influence the metabolic clearance of diazepam in young healthy volunteers.