Last updated: July 31, 2026
Ridaura is the U.S. brand for auranofin, an oral gold compound approved for rheumatoid arthritis (RA). Its clinical role has contracted sharply because of slow onset, adverse-effect monitoring, conventional DMARD alternatives, biologics and JAK inhibitors. Ridaura has no meaningful U.S. patent exclusivity remaining, no active FDA exclusivity, and no visible late-stage clinical program supporting a new commercial indication. The market is therefore a legacy specialty market with limited growth potential.
What is Ridaura and what is auranofin approved to treat?
Ridaura contains auranofin, an orally administered gold compound. FDA approved Ridaura in 1985 for the treatment of adults with active classical or definite rheumatoid arthritis who have not responded adequately to, or cannot tolerate, other antirheumatic drugs. The product is supplied as 3-mg tablets, with a usual maintenance dose of 6 mg daily after dose escalation when tolerated (FDA, 2013).
Ridaura is a disease-modifying antirheumatic drug, or DMARD. Its historical use was based on suppression of inflammatory activity and reduction of RA symptoms. Its clinical limitations include:
- Delayed onset of action, often requiring several months.
- Gastrointestinal adverse events.
- Oral and skin reactions.
- Proteinuria and potential renal toxicity.
- Hematologic toxicity, including thrombocytopenia, leukopenia and aplastic anemia.
- The need for periodic blood counts and urinalysis.
Modern RA guidelines generally favor methotrexate and other conventional synthetic DMARDs before escalation to biologic DMARDs or targeted synthetic DMARDs. Auranofin is rarely used in contemporary treatment algorithms because its benefit-risk profile is less competitive than those of current alternatives (Fraenkel et al., 2021).
What is the current FDA regulatory status of Ridaura?
Ridaura was approved under New Drug Application 018830. Its FDA-approved indication remains rheumatoid arthritis. It is not approved for cancer, HIV, COVID-19, inflammatory bowel disease or infectious diseases.
| Regulatory attribute |
Ridaura status |
| Active ingredient |
Auranofin |
| Dosage form |
3-mg oral tablet |
| FDA indication |
Rheumatoid arthritis |
| Original approval |
1985 |
| NDA |
018830 |
| FDA exclusivity |
Expired |
| Current regulatory pathway |
Legacy NDA |
| Biologic status |
Not a biologic |
| Biosimilar pathway |
Not applicable |
| Orange Book relevance |
Small-molecule drug; patent listing and marketing status must be checked against the current FDA Orange Book |
FDA’s labeling history shows that Ridaura’s approval is old and that the product does not have the regulatory protections associated with a recently approved drug. Any current commercial protection would have to arise from an unexpired patent, a new formulation, a new indication, manufacturing know-how or market access rather than original approval exclusivity (FDA, 2013).
What patents protect Ridaura and when does auranofin lose exclusivity?
Ridaura has no commercially meaningful composition-of-matter exclusivity remaining. Auranofin was developed decades ago, and the original patent term would have expired long before the current market period.
| Protection category |
Ridaura assessment |
| Original active-ingredient protection |
Expired |
| Original product protection |
Expired |
| FDA five-year NCE exclusivity |
Expired |
| Three-year new clinical investigation exclusivity |
None currently identified |
| Orphan-drug exclusivity |
None |
| Pediatric exclusivity |
None currently identified |
| Formulation patents |
No widely recognized active U.S. barrier supporting the branded product |
| Method-of-use patents |
No active method-of-use estate publicly associated with the approved RA product |
| Manufacturing patents |
Potentially relevant to a new sponsor, but not a barrier to the legacy RA indication |
| Biosimilar protection |
Not applicable |
The principal entry risk is therefore regulatory and commercial, not patent-based. An approved generic auranofin tablet could ordinarily challenge any listed patent through an ANDA Paragraph IV certification if an unexpired Orange Book patent existed. Because the underlying drug is old, a Paragraph IV campaign would be unlikely to create a durable moat unless a later patent covered a specific formulation, dosing regimen or manufacturing process.
How many patents cover Ridaura in the Orange Book?
The relevant Orange Book question is whether NDA 018830 has any unexpired listed patents. The original auranofin patents cannot provide current exclusivity because of age. A current Orange Book listing, if present, would need to relate to a later-approved formulation or use rather than the original active ingredient.
The commercial significance of any listing would depend on:
- Patent expiration date.
- Whether the patent covers the 3-mg tablet or only a narrow use.
- Whether the FDA lists the patent as product, formulation or method-of-use protection.
- Whether a generic applicant has filed a Paragraph IV certification.
- Whether the brand holder initiated litigation within the 45-day statutory period.
No major, publicly established Ridaura patent litigation campaign is associated with the product’s legacy RA indication. The absence of a visible litigation record is consistent with a small market and an aged product.
What clinical trials are evaluating auranofin?
Auranofin has attracted research interest outside RA because gold compounds can affect redox signaling, thioredoxin reductase and other cellular pathways. That research does not mean that Ridaura has a new approved indication.
Rheumatoid arthritis trials
The RA evidence base is old. Ridaura was studied before the current trial-registration era, and its pivotal evidence predates today’s placebo-controlled biologic and treat-to-target standards. The product’s delayed activity and toxicity profile have limited its relevance in current comparative trials.
Cancer research
Auranofin has been investigated in preclinical and early clinical oncology research, including studies involving hematologic malignancies and solid tumors. These programs have generally evaluated auranofin as an investigational anticancer agent, not as Ridaura under its approved RA label. The available development history has not produced an FDA-approved cancer indication.
Infectious-disease research
Auranofin has shown antimicrobial or antiviral activity in laboratory and animal studies. During the COVID-19 pandemic, research groups examined gold-compound mechanisms involving viral replication and host-cell pathways. These findings did not establish clinical efficacy for COVID-19, and auranofin has not received FDA approval for that disease.
Other repurposing areas
Research has included parasitic infections, bacterial infections, HIV-related mechanisms, neurodegenerative disease and inflammatory disorders. These efforts have remained exploratory or early-stage. No late-stage registration program has established a new commercial indication for Ridaura.
| Development area |
Clinical status |
Commercial effect on Ridaura |
| Rheumatoid arthritis |
Approved, legacy use |
Supports only a narrow residual market |
| Oncology |
Investigational and early-stage research |
No approved expansion |
| COVID-19 |
Preclinical or exploratory evidence |
No validated clinical franchise |
| Infectious disease |
Early research |
No regulatory approval |
| Neurologic and inflammatory disease |
Exploratory |
No established revenue contribution |
ClinicalTrials.gov is the appropriate source for current interventional-study status. Trial records should be distinguished from preclinical publications, investigator-initiated studies and trials of other gold compounds that do not use auranofin (National Library of Medicine, 2024).
What is the market size for Ridaura?
Ridaura is a niche product with limited commercial visibility. Public company filings do not generally report Ridaura revenue as a separate material line item. Reliable global sales estimates are therefore difficult to establish from public sources.
The addressable market is constrained by:
- A small residual population of RA patients receiving oral gold therapy.
- Competition from low-cost methotrexate, hydroxychloroquine, sulfasalazine and leflunomide.
- Competition from biologic TNF inhibitors, interleukin inhibitors, abatacept, rituximab and JAK inhibitors.
- Slow onset and safety monitoring.
- Physician preference for guideline-supported treat-to-target regimens.
- Limited investment in promotion and clinical development.
- Potential availability of compounded or alternative gold products in some markets.
The relevant market is not the total RA drug market. Ridaura competes for a small refractory or intolerance-driven segment after other DMARD options have been considered.
Market positioning versus current RA therapies
| Product class |
Typical role in RA |
Relative position versus Ridaura |
| Methotrexate |
Standard first-line conventional DMARD |
Lower cost, stronger guideline position |
| Hydroxychloroquine |
Mild disease or combination therapy |
Better established in selected patients |
| Sulfasalazine |
Conventional DMARD |
More common in treatment algorithms |
| Leflunomide |
Alternative conventional DMARD |
Faster and more familiar contemporary use |
| Biologic DMARDs |
Moderate-to-severe disease |
Higher efficacy and strong evidence base |
| JAK inhibitors |
Targeted advanced therapy |
Higher clinical and commercial investment |
| Auranofin |
Rare legacy option |
Narrow, declining clinical relevance |
What is the Ridaura market forecast?
A defensible forecast supports a flat-to-declining outlook rather than a growth case. No public evidence indicates a major new indication, a successful repurposing program or a proprietary reformulation capable of materially expanding demand.
Base-case forecast
The base case assumes:
- Continued availability in at least some markets.
- Stable but very low RA utilization.
- No successful new indication.
- No major branded promotional investment.
- Generic or alternative supply pressure where commercially viable.
- Continued substitution by modern DMARDs.
Under this scenario, volume is likely to decline gradually over the medium term. Revenue could be more volatile than volume because small specialty markets are sensitive to wholesaler inventories, supply interruptions and price changes.
Upside case
An upside case would require one of the following:
- Positive controlled clinical data in a new disease.
- A proprietary formulation with better tolerability or targeted delivery.
- A strategic acquisition by a specialty-pharmaceutical company.
- Regulatory approval for a new indication.
- Demonstrated utility in a treatment-resistant population with limited alternatives.
No established late-stage program currently supports assigning a high probability to this scenario.
Downside case
The downside case includes:
- Product discontinuation or supply interruption.
- Further migration to generic conventional DMARDs and advanced therapies.
- Manufacturing economics that no longer support low-volume production.
- Prescriber abandonment as younger clinicians have less experience with oral gold therapy.
- Reimbursement restrictions.
The downside risk is more operational than patent-driven.
Which companies are challenging Ridaura?
No major, publicly visible Paragraph IV litigation campaign has defined the Ridaura market. That is consistent with the product’s small demand base and limited commercial incentive for an ANDA sponsor.
A generic entrant would likely assess:
- Whether an approved reference listed drug remains commercially available.
- Whether an ANDA can rely on the Ridaura NDA.
- Bioequivalence requirements for the 3-mg tablet.
- Stability and impurity controls for a gold-containing compound.
- Manufacturing economics at low expected volume.
- Any current Orange Book patents.
- State substitution and reimbursement dynamics.
The absence of high-profile litigation does not eliminate generic-entry risk. It indicates that litigation has not been a central commercial feature of this product.
What manufacturing and intellectual-property barriers affect auranofin?
Auranofin has limited traditional IP protection, but manufacturing can still create practical barriers. Gold-containing active ingredients require control of elemental impurities, assay, content uniformity, dissolution, stability and process reproducibility. A sponsor must also maintain appropriate controls for the finished tablet and demonstrate bioequivalence.
These barriers are technical and economic rather than exclusivity-based. Low demand can make commercial launch unattractive even when legal entry is available. A manufacturer with an established specialty-drug platform could enter without relying on a broad patent estate, but the expected return would likely be limited.
What is the litigation and settlement status for Ridaura?
Ridaura has no widely reported active patent litigation comparable to disputes involving high-revenue biologics, oncology products or specialty formulations. No major branded-generic settlement has shaped the timing of auranofin entry.
Any future dispute would most likely involve:
- Orange Book patent certification.
- Product availability and reference-drug status.
- Bioequivalence or manufacturing issues.
- A new formulation or repurposed indication.
- Contractual supply or distribution rights.
The legacy RA product does not present a strong litigation platform.
How strong is the Ridaura patent estate?
The patent estate is weak from a current commercial perspective. The active ingredient and original product are old, FDA exclusivity has expired, and no recognized active formulation or use patent has created a material barrier around the approved RA tablet.
| Patent-strength factor |
Assessment |
| Composition-of-matter protection |
None remaining |
| Remaining regulatory exclusivity |
None |
| Formulation differentiation |
Limited public evidence |
| Method-of-use protection |
Limited public evidence |
| Manufacturing complexity |
Moderate technical barrier |
| Litigation leverage |
Low |
| Generic-entry exposure |
High if a viable ANDA sponsor emerges |
| Commercial moat |
Minimal |
Key Takeaways
- Ridaura is the legacy oral-gold RA product containing auranofin.
- FDA approved it in 1985 for adults with active rheumatoid arthritis.
- Its clinical use is now narrow because of delayed onset, toxicity monitoring and competition from modern DMARDs.
- Original patent and regulatory exclusivity have expired.
- No major active patent litigation or Paragraph IV campaign is publicly associated with the product.
- Auranofin repurposing research has not produced an FDA-approved new indication.
- Publicly reported Ridaura revenue is limited and not generally disclosed separately.
- The base-case market outlook is flat to declining, with high operational and generic-entry risk.
- The product has a weak current patent estate and little evidence of a near-term commercial expansion pathway.
FAQs About Ridaura and Auranofin
Is Ridaura still FDA approved?
Yes. Ridaura remains associated with FDA-approved auranofin labeling for rheumatoid arthritis, although commercial availability can vary by market and supplier.
Is auranofin a biologic or biosimilar?
No. Auranofin is a small-molecule chemical drug administered as an oral tablet. Biosimilar rules do not apply.
Can a generic company launch auranofin?
A generic company could pursue an ANDA if the reference-drug, bioequivalence, manufacturing and regulatory requirements are satisfied. The main obstacle is likely market economics rather than patent duration.
Is auranofin approved for COVID-19 or cancer?
No. Research has evaluated auranofin in infectious disease and oncology settings, but those investigations have not resulted in FDA approval for COVID-19 or cancer.
Does Ridaura have meaningful licensing value?
Its legacy RA indication has limited licensing value. A higher-value transaction would require validated clinical data, a differentiated formulation or a credible new-indication program.
References
-
Food and Drug Administration. (2013). Ridaura (auranofin) tablets: Prescribing information. U.S. Department of Health and Human Services.
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Fraenkel, L., Bathon, J. M., England, B. R., St. Clair, E. W., Arayssi, T., Carandang, K., Deane, K. D., Genovese, M., Huston, K. K., Kerr, G., Kremer, J., Nakamura, M. C., Russell, L. A., Singh, J. A., Smith, B. J., Sparks, J. A., Venkatachalam, S., & Weinblatt, M. E. (2021). 2021 American College of Rheumatology guideline for the treatment of rheumatoid arthritis. Arthritis Care & Research, 73(7), 924-939.
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National Library of Medicine. (2024). ClinicalTrials.gov: Auranofin interventional studies. U.S. National Institutes of Health.
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U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. U.S. Department of Health and Human Services.
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U.S. Food and Drug Administration. (2024). Drugs@FDA: FDA-approved drugs. U.S. Department of Health and Human Services.
