What factors can alter drug absorption in patients with gastrointestinal illness according to the chapter?

Factors that can alter drug absorption in patients with gastrointestinal illness include conditions affecting gastrointestinal peristalsis such as severe vomiting, diarrhea, and constipation, as well as the rate of gastric emptying. Inflammatory conditions affecting the gut wall can also impede drug transit into the blood. Nutritional imbalances caused by gastrointestinal diseases may further affect drug metabolism, leading to unexpected drug effects.