Sulfasalazine

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Cat Number

API0232164

CAS Number

599-79-1

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Product Detail Description Scientific Support Advanced Innovations Customer Q&A

CAS Number

599-79-1

Storage

Store at room temperature

Synonyms

Salicylazosulfapyridine; Azulfidine; Sulphasalazine; Salazopyrin; Benzosulfa; Sulcolon; Asulfidine; Azopyrine; Salazopyridin; Accucol; Azopyrin; Salisulf; Salazopiridazin

Molecular Formula

C18H14N4O5S

Molecular Weight

398.4

Smiles

C1=CC=NC(=C1)NS(=O)(=O)C2=CC=C(C=C2)N=NC3=CC(=C(C=C3)O)C(=O)O

Appearance

Light yellow to orange powder

Melting Point

260-265°C (dec.)

Boiling Point

689.3±65.0°C at 760 mmHg (Predicted)

Relative Density

1.5±0.1

General Description

Sulfasalazine is a prodrug consisting of 5‑aminosalicylic acid (5‑ASA) linked by an azo bond to sulfapyridine. The molecule is an orange‑red crystalline powder with poor water solubility. It was originally synthesized to deliver 5‑ASA to the colon while using sulfapyridine as a carrier. The azo bond is stable in the stomach and small intestine but cleaved by colonic bacteria.

Mechanism of Action

After bacterial azo reduction in the colon, the molecule splits into sulfapyridine and 5‑ASA. 5‑ASA acts locally to reduce inflammation by inhibiting cyclooxygenase and lipoxygenase pathways, scavenging free radicals, and blocking NF‑κB activation. Sulfapyridine is absorbed and has immunosuppressive effects, including inhibition of T‑cell proliferation and folate synthesis. The combined actions produce anti‑inflammatory and disease‑modifying effects.

Application

Sulfasalazine is indicated for the treatment of ulcerative colitis (mild to moderate), Crohn’s disease (colonic involvement), and rheumatoid arthritis. It is also used for ankylosing spondylitis and psoriatic arthritis. The drug is effective in maintaining remission in ulcerative colitis but is less effective for isolated small bowel Crohn’s disease.

xCT protein expression is upregulated in gastric cancer tissues and cells, correlating with advanced tumor stage and poor overall survival. Sulfasalazine, an xCT inhibitor, attenuated proliferation, colony formation, migration, and invasion in HGC‑27 and AGS cells (high xCT expressers) in vitro. The effects were less pronounced in cells with lower xCT expression. Further validation is required, but sulfasalazine shows promise as an anti‑metastatic agent in gastric cancer.

Fig. 1 The effect of sulfasalazine on the proliferation, colony formation, metastasis and invasion of gastric cancer. (Zhuang J, et al., 2021)

References

Zhuang J, et al. Sulfasalazine, a potent suppressor of gastric cancer proliferation and metastasis by inhibition of xCT: Conventional drug in new use. J Cell Mol Med. 2021;25(12):5372-5380.

In human hepatocellular carcinoma (HCC) cell lines HEPG2 and Huh‑7, imatinib (tyrosine kinase inhibitor) and sulfasalazine (NFκB inhibitor) synergistically down‑regulated c‑MET gene expression, inhibited proliferation, and induced apoptosis. The combination affected PI3K/Akt, p‑STAT‑3, BCR‑Abl, and NFκB pathways. Sulfasalazine potentiates the antitumor effects of imatinib, suggesting a potential second‑line strategy for HCC patients progressing on sorafenib/regorafenib.

Fig. 2 Effects of imatinib (1, 1.2 µm), sulfasalazine (SSZ) (250, 253 µm) and their combination on c‐MET gene expression levels in (A) HEPG2 and (B) Huh‐7 cell lysates. (Shamaa MM, 2021)

References

Shamaa MM. Sulfasalazine synergistically enhances the inhibitory effects of imatinib against hepatocellular carcinoma (HCC) cells by targeting NFκB, BCR/ABL, and PI3K/AKT signaling pathway-related proteins. FEBS Open Bio. 2021;11(3):588-597.

Does Sulfasalazine require protection from light during storage?

Yes, it is photosensitive. Light exposure causes discoloration and degradation of the azo bond. Store in light-resistant containers, preferably amber glass.

What is the recommended storage temperature for Sulfasalazine?

Store at controlled room temperature (15-25°C). Avoid excessive heat above 30°C, which accelerates reductive cleavage to sulfapyridine and mesalamine.

Is Sulfasalazine stable under high-humidity conditions?

It is slightly hygroscopic. Under high humidity (>70% RH), it may clump but chemical degradation is minimal. Store with desiccant for flowability.

How is the impurity sulfapyridine (azo reduction product) monitored?

This degradation product is quantified using a stability-indicating HPLC method, ensuring it remains below pharmacopoeial limits.