Olsalazine

Inflammatory bowel disease (IBD) is a chronic intestinal disease with recurrent attacks. Patients usually require long-term medication to control the disease, while the adverse reactions of traditional sulfasalazine limit its long-term clinical application. Olsalazine is a 5-aminosalicylic acid anti-ulcer drug. Its mechanism of action is that two molecules of 5-aminosalicylic acid are connected via an azo bond, and the active ingredient is only cleaved and released by intestinal bacteria after reaching the colon, which avoids the premature absorption of the active ingredient in the stomach and small intestine, and greatly reduces the risk of systemic adverse reactions. It is mainly used clinically for the treatment and maintenance of remission of mild to moderate ulcerative colitis, and is the first-line alternative drug for patients intolerant to sulfonamides. It is also suitable for adult and pediatric patients who require long-term control of inflammatory bowel disease.

The global olsalazine market size was approximately USD 180 million in 2023, and it is expected to grow steadily at a compound annual growth rate of 3.2% from 2024 to 2030. The growth drivers mainly come from the year-on-year increase in the prevalence of inflammatory bowel disease and the improvement of patients' long-term treatment compliance. The domestic market is still dominated by generic drug supply at present. Three enterprises have obtained approval for olsalazine sodium capsule preparations, which have not been included in the national centralized volume-based procurement, so the demand for API supply is stable. Moreover, with the continuous standardization of the clinical pathway for ulcerative colitis, the clinical demand for high-quality APIs will be further released.

The original developer of olsalazine is Pharmacia & Upjohn AB (a subsidiary of Pfizer), with the original brand name Dipentum®. The core compound patent expired globally in 2001. The approved dosage form of the original drug is oral capsule with a specification of 250mg, which has been included in the FDA Orange Book Reference Listed Drug Catalog, and also included in the *Catalog of Reference Listed Drugs for Chemical Drugs* of China. In terms of domestic API registration, as of now, there are 4 registration numbers for olsalazine sodium APIs, 3 of which are in Status A and can be legally supplied for domestic preparation production. Domestic preparation products such as olsalazine sodium capsules have been approved for marketing. (Data as of October 2025, please refer to the official website of CDE for the latest information)

CATO provides a full set of olsalazine impurity reference standards, most of which are in stock. For in-stock products, orders placed before 16:00 will be shipped on the same day. The products can meet the compliance requirements of multiple regulations such as Chinese Pharmacopoeia and FDA, and provide stable reference standard support for API R&D, quality research and preparation consistency evaluation.