Effect of antibiotic pretreatment on glycoside/glycosidase-based colonic drug delivery

The effect of antibiotic pretreatment on the intestinal distribution and hydrolysis of the prodrug prednisolone-beta-D-glucoside was studied in rats. A combination of neomycin, lincomycin, and metronidazole was administered twice daily by gastric intubation for three days to young adult male rats. On the fourth day, prednisolone-beta-D-glucoside was administered intragastrically. The distribution of prodrug and drug in the intestinal contents was significantly altered by the antibiotic treatment. In comparison with untreated rats, stomach to cecum transit time appeared to be reduced, and more prodrug was hydrolyzed in the small intestine. In addition, an appreciable amount of the dose was retained longer in the small intestine of treated animals. The total recovery of prodrug and drug was unaltered by the pretreatment. Possible explanations for the observed results are presented.