- Patients with a pre-existing condition interfering with normal gastrointestinal anatomy or motility, and/or hepatic function that could interfere with the absorption, metabolism, and/or excretion of the study drugs. Examples of conditions that could interfere with normal gastrointestinal anatomy or motility include gastrointestinal bypass surgery, partial or total gastrectomy, small bowel resection, vagotomy, malabsorption, Crohn's disease, ulcerative colitis, or celiac sprue.