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Mesalazine structure.svg
Clinical data
Trade namesAsacol, Lialda, Pentasa, others[1]
Other namesmesalamine, 5-aminosalicylic acid, 5-ASA, Mesalamine (USAN US)
License data
Routes of
By mouth, rectal
ATC code
Legal status
Legal status
Pharmacokinetic data
Bioavailabilityorally: 20–30% absorbed
rectally: 10–35%
MetabolismRapidly & extensively metabolized intestinal mucosal wall and the liver
Elimination half-life5 hours after initial dose.
At steady state 7 hours
  • 5-Amino-2-hydroxybenzoic acid
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.001.745 Edit this at Wikidata
Chemical and physical data
Molar mass153.137 g·mol−1
3D model (JSmol)
Melting point283 °C (541 °F)
  • O=C(O)c1cc(ccc1O)N
  • InChI=1S/C7H7NO3/c8-4-1-2-6(9)5(3-4)7(10)11/h1-3,9H,8H2,(H,10,11) checkY

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.[1] It is generally used for mildly to moderately severe disease.[1] It is taken by mouth or rectally.[1] The formulations which are taken by mouth appear to be similarly effective.[8]

Common side effects include headache, nausea, abdominal pain, and fever.[1] Serious side effects may include pericarditis, liver problems, and kidney problems.[1][8] Use in pregnancy and breastfeeding appears safe.[8] In people with a sulfa allergy certain formulations may result in problems.[1] Mesalazine is an aminosalicylate and anti-inflammatory.[1][8] It works by direct contact with the intestines.[1]

Mesalazine was approved for medical use in the United States in 1987.[1][4] It is on the World Health Organization's List of Essential Medicines.[9] It is available as a generic medication and sold under many brand names worldwide.[10][1] In 2019, it was the 229th most commonly prescribed medication in the United States, with more than 2 million prescriptions.[11][12]

Medical uses[edit]

It is used to treat inflammatory bowel disease, including ulcerative colitis and Crohn's disease (effective only in colonic diseases).[1] It is generally used for mildly to moderately active disease.[1] It is taken by mouth or rectally.[1] The formulations which are taken by mouth appear to be similarly effective.[8]

Side effects[edit]

There are 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,[3] people with kidney disease,[3] or people who are allergic to aspirin.[3]

Side effects are primarily gastrointestinal but may also include headache; GI effects include nausea, diarrhea 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.[3]


Mesalazine is the active moiety of sulfasalazine, which is metabolized to sulfapyridine and mesalazine.[13] It is also the active component of the prodrug balsalazide along with the inert carrier molecule 4-aminobenzoyl-beta-alanine.[14] It is in the category of disease-modifying antirheumatic drugs (DMARDs) family of medications.[15] It is unclear exactly how it works.[15]

Mechanism of action[edit]

Exact mechanism of mesalazine is unknown, but is speculated that mesalazine decreases synthesis of prostaglandin and leukotriene, modulating the inflammatory response derived from the cyclooxygenase and lipooxygenase pathways.[16] It appears to act locally on colonic mucosa.[17]

Society and culture[edit]

Brand names[edit]

Mesalazine is sold under various names including Apriso, Asacol, Asacol HD, Canasa, Delzicol, Fivasa, Lialda, Pentasa, Rowasa, and Sfrowasa.[18][19]


  1. ^ a b c d e f g h i j k l m n "Mesalamine Monograph for Professionals". American Society of Health-System Pharmacists.
  2. ^ "Mesalamine Use During Pregnancy". 18 September 2018. Retrieved 30 December 2019.
  3. ^ a b c d e "Asacol 400mg MR Tablets - Summary of Product Characteristics (SmPC)". (emc). 14 April 2016. Retrieved 30 December 2019.
  4. ^ a b "Asacol HD- mesalamine tablet, delayed release". DailyMed. 15 April 2018. Retrieved 30 December 2019.
  5. ^ "Pentasa- mesalamine capsule". DailyMed. 8 November 2021. Retrieved 17 May 2022.
  6. ^ "Lialda- mesalamine tablet, delayed release". DailyMed. 8 November 2021. Retrieved 17 May 2022.
  7. ^ Human Medicines Evaluation Division (15 October 2020). "Active substance: mesalazine" (PDF). List of nationally authorised medicinal products. European Medicines Agency.
  8. ^ a b c d e British national formulary : BNF 76 (76 ed.). Pharmaceutical Press. 2018. pp. 39–41. ISBN 9780857113382.
  9. ^ World Health Organization (2021). World Health Organization model list of essential medicines: 22nd list (2021). Geneva: World Health Organization. hdl:10665/345533. WHO/MHP/HPS/EML/2021.02.
  10. ^ "ANDA Approval Reports - 2017 First Generic Drug Approvals". Food and Drug Administration (FDA). 3 November 2018. Retrieved 8 April 2019.
  11. ^ "The Top 300 of 2019". ClinCalc. Retrieved 16 October 2021.
  12. ^ "Mesalamine - Drug Usage Statistics". ClinCalc. Retrieved 16 October 2021.
  13. ^ Richard Finkel R, Clark MA, Cubeddu LX (2009). Lippincott's Illustrated Reviews: Pharmacology (Fourth ed.). ISBN 978-0-7817-7155-9.
  14. ^ "Balsalazide: increasing the choice for patients with ulcerative colitis". Drugs & Therapy Perspectives. 19 (1–4): 1–4. 2003. doi:10.2165/00042310-200319100-00001. S2CID 195230977.
  15. ^ a b "Sulfasalazine". The American Society of Health-System Pharmacists. Archived from the original on 21 December 2016. Retrieved 8 December 2016.
  16. ^ Nakashima J, Preuss CV (2022). "Mesalamine (USAN)". StatPearls. Treasure Island (FL): StatPearls Publishing. PMID 31869178. Retrieved 2022-09-01.
  17. ^ Iacucci M, de Silva S, Ghosh S (February 2010). "Mesalazine in inflammatory bowel disease: a trendy topic once again?". Canadian Journal of Gastroenterology. 24 (2): 127–133. doi:10.1155/2010/586092. PMC 2852235. PMID 20151072.
  18. ^ "Substance Name: Mesalamine [USAN:USP]". ChemIDplus. Retrieved 2 October 2020.
  19. ^ "Mesalamine Uses, Side Effects & Warnings". 30 August 2019. Retrieved 2 October 2020.

External links[edit]

  • "Mesalamine". Drug Information Portal. U.S. National Library of Medicine.