**3. Maldigestion and malabsorption**

Small intestine is involved in both digestive and absorptive processes of all major nutrients, fatty acids and multiple ions, occurring across the entire intestinal wall at different levels. Normal functional anatomy includes a full bowel length, normal intestinal villi and absorptive capacity, conserved neuroendocrine regulatory systems, and a normal motility activity, particularly the major motor complex (MMC) [10]. Several drugs may interfere with one or multiple mechanisms associated with either digestion processes or mechanisms associated with intestinal absorption. Alphaglucosidase inhibitors such as acarbose decrease carbohydrate digestion, lipaseinhibitors such as orlistat and cetilistat affect fat absorption, bile acid binding resins such as cholestyramine or colestipol affects not only bile acid absorption but also that

#### **Figure 1.** *Pathophysiologic mechanisms of enteropathy according to drug type.*
