Colonic side effects of nonsteroidal antiinflammatory drugs.

Non-steroidal anti-inflammatory drugs (NSAIDs) are a widely prescribed group of drugs, known to be responsible for many cases of gastroduodenal ulcers by inhibiting cyclo-oxygenase (1). The incidence of side effects while taking NSAID therapy is high, and has been reported to approach 70% in patients receiving long-term therapy. The most frequent complications are those involving the gastroduodenal mucosa, and they range from nonspecific gastritis to peptic ulceration. Although mucosal injury by NSAIDs does not seem to be particularly morefrequent in elderly patients, they experience more severe complications (bleeding and perforation). Colonic side effects of NSAIDs are rare, but they have increasingly been reported since the advent of colonoscopy (24). NewNSAIDs, formulations with enteric coating or slow release may prevent gastroduodenal ulceration, but increase the risk of colonic damage. Colitis in previously asymptomatic patients has been associated with a number of NSAIDs; it has been estimated that as many as 10% of newly diagnosed cases of colitis may be secondary to NSAID use. Most of these patients present with diarrhea and macro or microscopic lower gastrointestinal bleeding. Gibson et al reviewed 40 cases of NSAID related colitis (2); endoscopy revealed a varied range of inflammatory changes, and solitary or multiple ulcers can occur. Interestingly all patients rechallenged with NSAIDs (after previous withdrawal of the medication) experienced relapse. Several other conditions have been described in patients taking NSAIDs: ischemic colitis, colonic hemorrhage and perforation, perforation of colonic diverticula, proctitis (related to suppository use), eosinophilic colitis, diaphragm-like stricture formationand colonic ulcer. Beh^et's disease may affect the gastrointestinal tract, especially the ileocecal area; it is more prevalent in Japan than in Western countries. An ileo-colonic ulcer in a patient with the typical manifestations of recurrent oral aphthous ulcers, ulcerating genital lesions and ocular lesions can be easily diagnosed with Behget's disease; on the other hand in the absence of the triple symptom complex, such lesion is called "simple ulcer". Such nonspecific ulcers are found predominantly in the cecum. Their etiology is unknown, and therefore can not be diagnosed before having ruled out other causes of colonic ulceration. Several hypotheses have been suggested to explain the origin of these ulcerations. A possible ischemic injury has been proposed in view of the identification of vascular abnormalities in areas adjacent to nonspecific colon ulcers; however the discordance between the usual location of nonspecific ulcers and ischemic colitis makes this hypothesis improbable. Nonspecific ulcers originating from the ulceration of cecal diverticula might explain nonspecific ulcers, as it has been confirmed in some cases. However, it is evident that most diverticula never ulcerate; moreover cecal diverticula are usually located on the mesenteric side of the cecum, whereas cecal ulcers are found on the antimesenteric border.