Product Information

Registration Status: Active

SALAZOPYRIN EN-TABLET 500mg is approved to be sold in Singapore with effective from 1988-01-06. It is marketed by PFIZER PTE LTD, with the registration number of SIN01589P.

This product contains Sulfasalazine 500mg in the form of ENTERIC-COATED TABLET. It is approved for ORAL use.

This product is manufactured by Kemwell AB in SWEDEN.

It is a Prescription Only Medicine that can only be obtained from a doctor or a dentist, or a pharmacist with a prescription from a Singapore-registered doctor or dentist.



A drug that is used in the management of inflammatory bowel diseases. Its activity is generally considered to lie in its metabolic breakdown product, 5-aminosalicylic acid (see mesalamine) released in the colon. (From Martindale, The Extra Pharmacopoeia, 30th ed, p907)


For the treatment of Crohn's disease and rheumatoid arthritis as a second-line agent.

Mechanism of Action

The mode of action of Sulfasalazine or its metabolites, 5-aminosalicylic acid (5-ASA) and sulfapyridine (SP), is still under investigation, but may be related to the anti-inflammatory and/or immunomodulatory properties that have been observed in animal and in vitro models, to its affinity for connective tissue, and/or to the relatively high concentration it reaches in serous fluids, the liver and intestinal walls, as demonstrated in autoradiographic studies in animals. In ulcerative colitis, clinical studies utilizing rectal administration of Sulfasalazine, SP and 5-ASA have indicated that the major therapeutic action may reside in the 5-ASA moiety. The relative contribution of the parent drug and the major metabolites in rheumatoid arthritis is unknown.


* 1 L/h [IV administration]

Active Ingredient/Synonyms

2-Hydroxy-5-((4-((2-pyridinylamino)sulfonyl)phenyl)azo)benzoic acid | 2-Hydroxy-5-[4-(pyridin-2-ylsulfamoyl)-phenylazo]-benzoic acid | 4-(Pyridyl-2-amidosulfonyl)-3'-carboxy-4'-hydroxyazobenzene | 5-((P-(2-Pyridylsulfamoyl)phenyl)azo)salicylic acid | 5-(4-(2-Pyridylsulfamoyl)phenylazo)-2-hydroxybenzoic acid | 5-(P-(2-Pyridylsulfamyl)phenylazo)salicylic acid | Azopyrin | Salazosulfapiridina | Salazosulfapyridine | Salazosulfapyridinum | Salicylazosulfapyridine | Sulfasalazin | Sulfasalazina | Sulfasalazine | Sulfasalazinum | Sulfasalazine |

Source of information: Drugbank (External Link). Last updated on: 3rd July 18. *Trade Name used in the content below may not be the same as the HSA-registered product.


  1. Health Science Authority of Singapore - Reclassified POM
  2. Drugbank