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Mesalazine, also known as mesalamine or 5-aminosalicylic acid (5-ASA), is a medication used to treat inflammatory bowel disease, including ulcerative colitis and Crohn's disease. It works by direct contact with the intestines. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. In 2023, it was the 202nd most commonly prescribed medication in the United States, with more than 2million prescriptions.
Medical uses
It is used to treat inflammatory bowel disease, including ulcerative colitis and Crohn's disease (effective only in colonic diseases).
Side effects
Most often reported side effects are headache, nausea, diarrhea, and abdominal pain.
Pregnancy
There is no data on use in pregnant women, but the drug does cross the placenta and is excreted in breast milk. The drug should not be used in children under two years of age, It appears to act locally on colonic mucosa. In 2025, mesalazine was reported to bind tubulin and stabilize microtubules.
Chemistry
Mesalazine is an active metabolite of sulfasalazine, which is metabolized to sulfapyridine and mesalazine. It is also the active metabolite of the prodrugs balsalazide (accompanied by the inert carrier molecule 4-aminobenzoyl-β-alanine) and olsalazine (which is metabolized to two equivalents of mesalazine). It is in the category of disease-modifying antirheumatic drugs (DMARDs) family of medications. It is unclear exactly how it works.
Mesalazine has application in the synthesis of Crisdesalazine, Fendosal [53597-27-6] & Parsalmide [30653-83-9].
Society and culture
Brand names
Mesalazine is sold under various names including Apriso, Asacol, Asacol HD, Canasa, Delzicol, Fivasa, Lialda, Salofalk, Pentasa, Rowasa, Octasa, and Sfrowasa. In Europe, it is sold under the name Salofalk (rectal suppository).