• 5-aminosalicylic acid
• ulcerative colitis
• Crohn' disease
• inflammatory bowel disease

When Asacol commands 65% of the UK market, can so many British gastroenterologists be wrong? Possibly. The market leader in France is Pentasa (72%) and is Salofalk in Germany (57%). In Canada it is Asacol (46%). Nevertheless, a Cochrane review of 11 trials involving 1598 patients showed that sulphasalazine was more effective than other 5-aminosalicylic acid (5-ASA) drugs for maintaining remission in ulcerative colitis (odds ratio (OR) 1.29, confidence interval (CI) 1.06–1.57).¹ Diagnosis, disease location, activity, side effect profile, efficacy, and cost all affect the choice of 5-ASA.

5-ASA acts on and is metabolised by intestinal epithelial cells. Consequently, ulcerative colitis (a mucosal disease) is more susceptible to treatment by 5-ASA than transmural Crohn's disease. Mega doses of mesalazine (≥4 g/day) may be an initial alternative to steroids for mild-moderately active ulcerative colitis and reduce the risk of relapse after small intestinal (but not colonic) resection for Crohn's disease.^{2 …}