Sulfasalazine

Evidence Level: L5

Predicted Indications: 8

Sulfasalazine

Pharmacist Assessment Report

Sulfasalazine: From Rheumatoid Arthritis and Inflammatory Bowel Disease to Brachydactyly-Syndactyly Syndrome

One-Sentence Summary

Sulfasalazine is an established anti-inflammatory drug, originally used for rheumatoid arthritis, ulcerative colitis, inflammatory bowel disease, juvenile arthritis and spondyloarthropathy. The top-ranked TxGNN predictions are mostly rare genetic disorders with no supporting evidence. The only prediction with a plausible rationale is osteoarthritis, which has 0 clinical trials and 20 publications (mostly preclinical or indirect). This report therefore focuses on osteoarthritis (rank 5), as the most credible candidate among the top 10 predictions.

Quick Overview

Item	Content
Original Indication	Rheumatoid arthritis, ulcerative colitis, inflammatory bowel disease, juvenile idiopathic arthritis, spondyloarthropathy
Predicted New Indication	Osteoarthritis (TxGNN rank 5; the rank 1 prediction, brachydactyly-syndactyly syndrome, has no supporting evidence)
TxGNN Prediction Score	0.9964 (osteoarthritis); 0.9994 (rank 1, brachydactyly-syndactyly syndrome)
Evidence Level	L5 (preclinical only, for osteoarthritis); L5 for rank 1
India Market Status	Listed in a compiled Indian medicine price dataset (at least 20) – CDSCO approval status is not included in this data
Number of Listed Products	at least 20
Recommended Decision	Hold (rank 1 prediction); research question for osteoarthritis

Why is This Prediction Reasonable?

Detailed mechanism of action data is not available in the data compiled for this report. Based on known information, sulfasalazine is an anti-inflammatory agent with demonstrated efficacy in inflammatory arthritis and bowel disease. It is thought to act partly through NF-kB inhibition and, in the preclinical literature, through inhibition of the cystine/glutamate antiporter (system xc-/xCT), which is linked to ferroptosis.

For osteoarthritis, the link is plausible but unproven. Preclinical studies show that:

Sulfasalazine blocked release of proteoglycan and collagen from cytokine-stimulated cartilage and down-regulated metalloproteinases (PMID 19690126).
It reduced cartilage destruction in an ACL transection and meniscectomy model, through inhibition of the cystine/glutamate antiporter (PMID 26466556).
A sulfasalazine-hyaluronic acid formulation reduced inflammation and cartilage degradation in a rat osteoarthritis model (PMID 29548914).
It altered the protein profile of articular chondrocytes in vitro (PMID 24329131).

No human trials were identified, so efficacy and safety in osteoarthritis are unestablished.

The other top predictions (colobomatous microphthalmia-rhizomelic dysplasia syndrome, congenital hypotrichosis with juvenile macular dystrophy, WHIM syndrome, acromesomelic dysplasia Hunter-Thompson type, brachyolmia-amelogenesis imperfecta syndrome, myosclerosis) are rare genetic developmental or connective-tissue disorders. No mechanistic link to sulfasalazine was found, and the high scores come from the TxGNN model (deep learning) and may reflect similarities the model learned between related diseases, not biological evidence. “Osteoarthritis susceptibility” is a genetic susceptibility entity, not a treatable condition. “Spondyloarthropathy, susceptibility to” is already an original indication, so it is not true repurposing.

Clinical Trial Evidence

Currently no related clinical trials registered for any of the top 10 predicted indications.

Literature Evidence

Selected publications for osteoarthritis (rank 5):

PMID	Year	Type	Journal	Key Findings
29548914	2018	Preclinical (rat model)	Int J Biol Macromol	Sulfasalazine-hyaluronic acid system gave sustained release for up to 60 days and attenuated inflammation and cartilage degradation in a rat osteoarthritis model
26466556	2016	Preclinical (animal model)	J Orthop Res	Attenuated cartilage destruction after ACL transection and meniscectomy via inhibition of the cystine/glutamate antiporter
19690126	2009	Preclinical (cartilage explant)	Rheumatology (Oxford)	Blocked release of proteoglycan and collagen from cytokine-stimulated cartilage and down-regulated metalloproteinases
24329131	2014	Preclinical (chondrocytes)	Mod Rheumatol	Sulfasalazine and tofacitinib changed the protein profile of articular chondrocytes
1673814	1991	Preclinical (in vitro)	Wien Klin Wochenschr	Effects of sulfasalazine and its metabolites on prostaglandin and leukotriene release from human synovial tissue
35958605	2022	Review	Front Immunol	General review of ferroptosis in inflammatory arthritis; not specific to sulfasalazine
24231065	2014	Systematic review	Semin Arthritis Rheum	Interstitial lung disease induced or exacerbated by DMARDs and biologics in rheumatoid arthritis
9567207	1998	Review	Curr Opin Rheumatol	Update on clinical trials in rheumatic diseases

For spondyloarthropathy (an existing indication), the retrieved literature is mainly reviews, plus a genetic association study (25413361, 2014, BMC Pharmacol Toxicol) linking NAT polymorphisms to sulfasalazine adverse drug reactions in Han Chinese patients with ankylosing spondylitis.

India Market Information

Sulfasalazine is marketed in India with 20 valid single-ingredient registrations. The approved indication text is not available in the data compiled for this report. Main authorizations:

Authorization Number	Product Name	Dosage Form	Approved Indication
207830	Sazomic 500 Tablet	Strip of 10 tablets	Not available
200246	Sulseas DS 1000mg Tablet	Strip of 10 tablets	Not available
206149	SSN 500 Tablet DR	Strip of 15 delayed-release tablets	Not available
200197	Salazopyrin 500mg Tablet	Strip of 10 tablets	Not available
199989	Salazar Tablet DR	Strip of 10 delayed-release tablets	Not available

All formulations are oral (tablets, delayed-release tablets and capsules).

Safety Considerations

Package insert warnings and contraindications were not available in the data compiled for this report. Please refer to the package insert for safety information.

Additional information available:

Disease-related contraindications (knowledge graph, not label text): porphyria (including inherited porphyria and porphyrin metabolism disease), kidney disease, liver disease, gallbladder disease, asthma (including intrinsic and allergic asthma), neutropenia, agranulocytosis, aplastic anemia, G6PD deficiency, slow acetylator status, glycogen storage disease, cystinuria, galactosemia, urinary tract obstruction, and pyoureter.
Drug interactions: 404 interactions were recorded. Major-level interactions include:
- Methenamine
- Prilocaine (topical)
- Human immunoglobulin G (intravenous)
Moderate-level examples include NSAIDs (ketorolac, ibuprofen, celecoxib), azathioprine, estrogens (estradiol, ethinylestradiol), amphotericin B, amikacin, acyclovir, alpelisib, apalutamide and asparaginase. Folic acid is a minor interaction.

Conclusion and Next Steps

Decision: Hold

Rationale:

The highest-scoring predictions (rank 1 to 4, 6, 7, 9, 10) are rare genetic disorders with no mechanistic link, no trials and no literature.
Osteoarthritis has plausible preclinical support but no human trials (Evidence Level L4), so it is best treated as a research question rather than a candidate for immediate development.

To proceed, the following is needed:

Mechanism of action data (for example from DrugBank).
The package insert, to complete warnings and contraindications and confirm approved indications (a blocking gap for safety screening).
Human data for osteoarthritis, such as a pilot or proof-of-concept trial, ideally exploring local delivery (e.g., sulfasalazine-hyaluronic acid) to limit systemic exposure.
Evaluation of the safety profile in an osteoarthritis population, considering the knowledge-graph contraindications (neutropenia, agranulocytosis, aplastic anemia, G6PD deficiency, slow acetylators) and the NSAID interactions that matter in osteoarthritis care.
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.