A 48-year-old man presents with a complaint of non-bloody diarrhea and right lower quadrant pain with a palpable mass and tenderness. He states that this "flare-up" is one of the worst he has ever experienced. Radiographic examination reveals evidence of ulceration, stricture, and fistula development of the colon and small bowel. Which of the following drugs would be MOST useful for treating this patient?

The patient is presenting with signs and symptoms suggestive of Crohn's disease, which is an idiopathic inflammatory process that can affect any poion of the alimentary tract. This condition is often characterized by intermittent bouts of low-grade fever, diarrhea, malaise, and weight loss, as well as focal tenderness and a palpable tender mass in the lower abdomen. There is radiographic evidence of ulceration, stricturing, or fistulas of the small intestine and colon. Nonpharmacologic therapy can be efficacious in some cases, but more severe cases may require coicosteroids, such as prednisone, which dramatically suppress the clinical signs and symptoms. Antidiarrheal agents (eg, diphenoxylate with atropine or loperamide) should be used very cautiously in these patients since there is a very high risk of toxic megacolon. Hydrocoisone suppositories are indicated for the treatment of distal ulcerative colitis, not Crohn's disease. Hyoscyamine is an anticholinergic agent that may allete the postprandial abdominal pain of a patient with irritable bowel syndrome when administered 30-60 minutes before a meal. Mesalamine is a 5-aminosalicylic acid derivative indicated for the treatment of ulcerative colitis. Although this agent may provide some benefit in the treatment of Crohn's disease, prednisone is the drug of choice for treatment of acute "flare-ups" seen in patients with this disease.