DOCTOR'S VIEWS ARCHIVE
However the way in which they are working is not clear. Both of these medications bind bile acids, which are chemicals made by the liver and secreted into the intestine. These bile acids may have effects on the way the muscle of the bowel functions. And so it is possible that by binding these bile acids, Questran and Colestid are affecting the muscles of the intestines. So there is at least a theoretical reason as to why these two drugs might work in controlling diarrhea.
Questran and Colestid are certainly reasonably safe with a few precautions. They must be taken at the right time because they also can bind other things like medications a patient is taking. So they are reasonable treatments, but again have not been proven to be effective in patients with irritable bowel syndrome.