<prompt> Treatment of choice for chronic ulcerative colitis is5 aminosalicylic acidAzathioprineMetronidazoleSalicylates  <response>: In mild to moderate cases of ulcerative colitis, the combination of a once-daily oral and a topical 5-aminosalicylate preparation is effective. MOA of the drug is it modulate cytokine release from mucosa. Reference : Davidson, 23rd Edition, page no : 820. 