EFFECT OF FAMOTIDINE ON CIPROFLOXACIN PHARMACOKINETICS AFTER SINGLE INTRAVENOUS AND ORAL DOSES IN RATS

The effect of intravenous (3.5 mg/kg) and oral (5 mg/kg) famotidine on ciprofloxacin pharmacokinetics after single (i.v.) intravenous (5 mg/ kg) and oral (20 mg/kg) doses were examined in the rat. Famotidine co- administration significantly increased the terminal elimination half-l ife of ciprofloxacin (54% and 29% following i.v. and oral administrati on, respectively) and tended to reduce the total body clearance by 27% and 34% following i.v. and oral routes, respectively. The area under the plasma concentration-time curve and the mean residence time in the body after i.v. and oral doses were significantly increased following famotidine co-administration. No changes in the steady-state apparent volume of distribution was observed after i.v. administration. The ma ximum plasma concentration and the time to peak concentration after or al dosing were also unaffected. These results suggest a possible reduc tion in the total clearance of ciprofloxacin, owing to inhibition of i ts renal tubular excretion by famotidine. Further studies are warrante d to determine whether this interaction occurs in humans.