I am a nurse practitioner student seeking information on protease inhibitors. What is the scientific basis of why protease inhibitors cause GI problems and diarrhea in patients? What is currently used to treat this side effect?

I am not sure if there is a unifying theme as to why PIs cause GI problems. There is a range of GI response to PIs with some (like atazanvir) having perhaps less GI side effects then others (full dose ritonavir is a gut bomb and even the very often used low dose boosting ritonavir has some modest GI side effects which often include bloating, gas, diarrhea). Taking the meds with food, immodium or lomotil, oat bran, calcium supplements and other interventions help patients which often have to be tried in a trial and error process. KH