Which medication in Jessica’s regimen serves as an antidiarrheal?

• A. Diphenoxylate (Lomotil)
• B. Prednisone
• C. Sulfasalazine
• D. Azathioprine

Answer: (A)

The concept being tested is recognizing a medication that relieves diarrhea by slowing gut movement. Diphenoxylate works as an antidiarrheal by acting on μ-opioid receptors in the intestinal wall, which reduces intestinal motility and increases water absorption, leading to fewer, more formed stools. It’s typically combined with atropine to discourage misuse and to provide a mild anticholinergic effect. This medication addresses symptoms of diarrhea rather than the underlying inflammation, so it’s used for symptom control in IBD rather than disease-modifying treatment. The other drugs in the regimen have different roles: prednisone reduces inflammation during flares, sulfasalazine is an anti-inflammatory 5-ASA used for mucosal healing and symptom control, and azathioprine is an immunosuppressant used for maintenance and steroid-sparing therapy. In summary, the antidiarrheal in Jessica’s regimen is the one that directly slows intestinal transit to lessen diarrhea.