EFFECT OF RANITIDINE ON RENAL CLEARANCE OF LOMEFLOXACIN

Objective. To examine the effect of ranitidine on the renal clearance of lomefloxacin, Setting: Department of Clinical Pharmacology, Jichi M edical School. Methods: Lomefloxacin 200 mg and ranitidine 300 mg or i ts placebo were given orally in a randomised, double-blind, crossover design. Blood and urine samples were obtained during a 24-h period aft er dosing. Results: The area under the plasma concentration-time curve and the elimination half-life of lomefloxacin were significantly incr eased following coadministration with ranitidine. These effects were c aused by significant decreases in total (7.8%) and renal (22%) clearan ce of lomefloxacin. In contrast, creatinine clearance and urinary excr etion of electrolytes were not influenced by ranitidine. Conclusion: A s lomefloxacin and ranitidine are excreted in urine by renal tubular s ecretion, the present results suggest that the renal tubular secretion of lomefloxacin is diminished by ranitidine. As the reduction in lome floxacin clearance is only marginal, it is probable that the drug inte raction observed in this study is not of clinical significance.