Effects of lactulose on intestinal functions in mice and rats

Effects of lactulose on transit of charcoal meals and the luminal water and insoluble contents in the intestinal tract of rats and mice were investigated. The ED50 value for lactulose to induce diarrhea was 3.8 g/kg (p.o.). The sufficient dose (5.4 and 8.6 g/kg, p.o.) needed to produce diarrhea increased the luminal water content of the small intestine and the caecum in rats and mice and sped transit of the intestinal charcoal in mice. In addition, the administration of lactulose at 5.4 g/kg significantly decreased the luminal insoluble contents of the rat small intestine. These results indicate the cathartic effect of lactulose in smaller animals such as rats as well as humans and suggest the possible application of full doses of lactulose to flush the luminal contents from the small intestine.