Sulfasalazine is metabolized by gut microbiota into sulfapyridine, the active metabolite in the treatment of rheumatoid arthritis (RA), and 5-aminosalicylic acid. Does 5-aminosalicylic acid play any significant pharmacological role?

The mechanisms of action of sulfasalazine are not fully understood. However, it is unlikely that 5-aminosalicylic acid plays a role in the treatment of RA. But you will come across 5-aminosalicylic acid in the treatment of inflammatory bowel disease, where it is thought to be the active metabolite of sulfasalazine and is also administered as a drug itself.