Patients with mild to moderate distal colitis may be treated with either oral aminosalicylates, topical mesalamine, or topical steroids. In patients refractory to oral aminosalicylates or topical corticosteroids, mesalamine enemas may still be effective. The unusual patient who is refractory to all of the above agents in maximal doses may require treatment with oral prednisone in doses up to 40-60 mg/day.
The therapeutic plan here is largely determined by the patient’s preference because either oral or topical therapy is effective. Oral therapy with aminosalicylates, either sulfasalazine, olsalazine, or mesalamine, is beneficial in achieving and maintaining remission    . Effective doses of sulfasalazine range between 4 and 6 g/day in four divided doses   ; for mesalamine, at least 2-4 g/day in divided doses   , and for olsalazine 1.5-3 g/day in divided doses     , although efficacy of olsalazine in active UC is not conclusively established, perhaps in part because of a confounding dose-related diarrhea. These drugs generally are efficacious within 2-4 weeks         and are effective in 40-80% of patients. Intolerance to the sulfapyridine moiety is not uncommon and may result in nausea, vomiting, dyspepsia, anorexia, and headache. More severe, but less common, adverse effects include allergic reactions, pancreatitis, hepatotoxicity, drug-induced connective tissue disease, bone marrow suppression, interstitial nephritis, nephrotoxicity, hemolytic anemia, or megaloblastic anemia. Abnormal sperm counts, motility, and morphology are related to the sulfapyridine moiety and are not seen with the mesalamine preparations. Approximately 80% of patients intolerant to sulfasalazine are able to tolerate olsalazine and mesalamine     . However, several of the allergic reactions previously thought to be due to the sulfa moiety have been seen with newer aminosalicylates as well  .
An alternative to oral aminosalicylates is topical therapy with either mesalamine suppositories or enemas, or cortisone foam or enemas. Mesalamine suppositories in a dose of 500 mg twice daily are effective in the treatment of proctitis  , and maintenance of remission  , while mesalamine enemas in doses of 2-4 g are able to reach as proximal as the splenic flexure and are effective in inducing  and maintaining remission in distal colitis     . Topical corticosteroids, available in the United States as a 100-mg hydrocortisone enema, or as a 10% cortisone foam, are effective in acute therapy of distal colitis   but have not proven effective in maintaining remission  . Mesalamine enemas in a dose of 4 g have been more successful than hydrocortisone 100-mg enemas in inducing remission in two double-blind controlled studies   . One-gram mesalamine enemas may prove as effective as the standard 4-g formulation  . Also, a 2-mg budesonide enema seems to be at least as effective if not more so than the standard hydrocortisone preparation with fewer side effects  (although not yet available in the United States).
Advantages of topical therapy include a generally quicker response time and a less frequent dosing schedule than oral therapy. The choice of topical vehicle is also guided by patient preference as well as by the proximal extent of disease: suppositories reaching approximately 10 cm, foam reaching approximately 15-20 cm, and enemas reaching up to the splenic flexure     . Some patients may achieve maximum benefit from combination of oral and topical therapy.