Mesalazine (INN, BAN), also known as mesalamine (USAN) or 5-aminosalicylic acid (5-ASA), is an aminosalicylate anti-inflammatory drug used to treat inflammatory bowel disease, including ulcerative colitis, inflamed anus or rectum, and to maintain remission in Crohn's disease.
It is sold in an oral form to maintain remission in Crohn's disease, and as a rectal suppository and an enema for the lower bowel conditions. It is generic and sold under many brand names worldwide, and there are many formulations.
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, people with kidney disease, or people who are allergic to aspirin.
Side effects are primary gastrointestinal but may include headache; GI effects include nausea, diarrhoea and abdominal pain. There have been scattered reports of various problems when the oral form is used, including problems caused by myelosuppression (leukopenia, neutropenia, agranulocytosis, aplastic anaemia, and thrombocytopenia, as well as hair loss, peripheral neuropathy, pancreatitis, liver problems, myocarditis and pericarditis, allergic and fibrotic lung reactions, lupus erythematosus-like reactions and rash (including urticaria), drug fever, interstitial nephritis and nephrotic syndrome, usually reversible on withdrawal. Very rarely, use of mesalazine has been associated with an exacerbation of the symptoms of colitis, Stevens Johnson syndrome and erythema multiforme.
Mesalazine is the active moiety of sulfasalazine, which is metabolized to sulfapyridine and mesalazine. It is also the active component of the prodrug balsalazide along with the inert carrier molecule 4-aminobenzoyl-beta-alanine.