Comparative tolerability of therapies for ulcerative colitis

This article reviews the clinical pharmacology, adverse events, and comparative tolerability of the drugs commonly available for treating ulcerative colitis. Synthetic glucocorticoids are the most commonly used conventional corticosteroids in the treatment of ulcerative colitis. Corticosteroids can be expected to impact on every organ system and most metabolic activities of the body. Suppression of the hypothalamic-pituitary-adrenal axis is common, but reversible, with conventional corticosteroids, but not with newer topically-acting corticosteroids. A serious complication of corticosteroids in children is growth retardation. The frequent adverse effects associated with the use of corticosteroids have prompted the development of a new group of rectal agents with equivalent efficacy and a more benign adverse event profile such as prednisolone metasulfobenzoate, fluticasone propionate, tixocortol pivalate, beclomethasone dipropionate and budesonide. The incidence of adverse effects related to the use of sulfasalazine (5-aminosalicylic acid plus sulfapyridine) is high and is dose related. The most frequently reported adverse effect is intolerance, not allergy, and relates to the sulfapyridine moiety correlating with the acetylator phenotype. Tolerance to 5-aminosalicylic acid by 80 to 90% of those patients allergic to, or intolerant of, sulfasalazine has given further evidence suggesting that the sulfa moiety is responsible for much of the toxicity of sulfasalazine. However, 10 to 20% of patients who are sulfasalazine intolerant have similar reactions to 5-aminosalicylic acid formulations, indicating that the 5-aminosalicylic acid moiety is responsible for adverse events in some patients taking sulfasalazine. Adverse effects resulting from treatment with azathioprine and mercaptopurine can be divided into two categories: allergic-type reactions that appear to be dose-independent and nonallergic-type reactions that are probably dose- and metabolism-dependent. It is well established now that genotype and thiopurine methyltransferase activity have an important impact on the rate of adverse effects during azathioprine or mercaptopurine therapy. Adverse effects resulting from high dose cyclosporin therapy for inflammatory bowel disease include: renal insufficiency, hypertension, opportunistic infections, seizures, paresthesias, tremor, headache, gingival hyperplasia, hypertrichosis, and anaphylaxis with intravenous cyclosporin. In contrast, the incidence of adverse events was relatively low when low-dose oral cyclosporin was used. The incidence of adverse events associated with any of the medications used in the treatment of ulcerative colitis is difficult to assess and it is therefore hard to make a comparative evaluation. The broadening of the drug regimen available to the clinician has advanced our knowledge about the disease, and further development of more effective, less toxic agents can be anticipated in the future.