Last updated: July 31, 2026
Aminosalicylate sodium, also called sodium para-aminosalicylate or sodium aminosalicylate, is an older antimycobacterial agent used mainly as a reserve drug for multidrug-resistant tuberculosis. Its commercial role is limited by gastrointestinal toxicity, frequent dosing, drug-interaction concerns, and the availability of newer medicines such as bedaquiline, delamanid and pretomanid. No broad, late-stage development program is evident for aminosalicylate sodium itself. Demand is tied to national tuberculosis programs, specialist procurement and patients requiring an alternative companion drug.
What is aminosalicylate sodium used for?
Aminosalicylate sodium is the sodium salt of para-aminosalicylic acid, or PAS. It inhibits growth of Mycobacterium tuberculosis through interference with folate metabolism and related bacterial pathways.
The drug is generally used as part of a combination regimen rather than as monotherapy. Current tuberculosis guidelines place PAS derivatives among agents with a limited or conditional role, particularly when preferred medicines cannot be used because of resistance, toxicity, contraindications or drug access limitations.[1]
| Attribute |
Aminosalicylate sodium |
| Active moiety |
Para-aminosalicylic acid |
| Therapeutic area |
Tuberculosis |
| Primary use |
Reserve treatment for drug-resistant tuberculosis |
| Typical administration |
Oral, divided doses |
| Drug class |
Antimycobacterial; folate-pathway antagonist |
| Main commercial form |
Granules or powder for oral administration |
| Principal users |
National TB programs, hospitals and specialty pharmacies |
| Major limitations |
Gastrointestinal intolerance, sodium load, frequent dosing and low positioning in modern MDR-TB algorithms |
Aminosalicylate sodium should be distinguished from aminosalicylic acid delayed-release products. These products deliver the same active moiety, but their regulatory status, formulation claims and patent positions may differ by jurisdiction.
What is the current clinical-trial status of aminosalicylate sodium?
The clinical-trial pipeline is inactive or very limited. Aminosalicylate sodium is not a leading candidate for new tuberculosis regimen development, and the current research emphasis is on shorter, all-oral regimens using newer drugs.
Most available evidence for PAS comes from:
- Historical tuberculosis studies.
- Retrospective treatment cohorts.
- Pharmacokinetic and tolerability studies.
- Combination-regimen studies in drug-resistant tuberculosis.
- Guideline reviews of older second-line medicines.
ClinicalTrials.gov contains tuberculosis studies that may include PAS or related background regimens, but the agent is generally not the investigational product. The distinction matters: inclusion as a permitted companion drug does not indicate an active development program or a new indication.[2]
Clinical development assessment
| Development category |
Status |
| New molecular entity program |
None identified |
| Phase 1 studies for aminosalicylate sodium |
No active development signal |
| Phase 2 efficacy program |
No current program of commercial significance identified |
| Phase 3 registration study |
None identified |
| Pediatric development |
Use may occur under tuberculosis-program protocols, but no major dedicated sodium-salt program is evident |
| New formulation development |
Limited and jurisdiction-specific |
| Biosimilar pathway |
Not applicable; this is a small-molecule drug |
| Combination-regimen development |
PAS may appear as an allowed background or salvage medicine |
The clinical value of PAS is therefore defensive rather than growth-oriented. It remains relevant when resistance patterns or tolerability limitations reduce the available regimen options, but it is not a central component of the current global pipeline.
How effective is aminosalicylate sodium in drug-resistant tuberculosis?
PAS has activity against M. tuberculosis, but its clinical use is constrained by tolerability and the availability of more effective or better-supported alternatives. The World Health Organization classifies older agents such as PAS within a lower-priority treatment framework than bedaquiline-based regimens.[1]
The principal clinical liabilities are:
- Gastrointestinal adverse effects, including nausea, abdominal discomfort and diarrhea.
- Hypersensitivity reactions.
- Hepatic and thyroid-related monitoring requirements.
- Sodium exposure, which can matter in patients with cardiovascular, renal or fluid-balance disorders.
- Large oral dosing burden and adherence difficulty.
- Lower attractiveness compared with modern oral MDR-TB medicines.
PAS can remain clinically relevant in individualized regimens, particularly when resistance or intolerance eliminates preferred agents. Its use is more likely in highly resistant tuberculosis, salvage therapy and settings where newer medicines are unavailable.
What are the FDA and regulatory statuses of aminosalicylate sodium products?
The U.S. regulatory record is associated mainly with aminosalicylic acid products rather than a widely marketed standalone sodium-salt product. PASER, an aminosalicylic acid delayed-release granule product, has been used for tuberculosis treatment in combination with other antimycobacterial agents.[3]
FDA status
| Regulatory issue |
Assessment |
| FDA therapeutic area |
Tuberculosis |
| Product type |
Small-molecule oral antimycobacterial |
| Regulatory pathway |
Conventional drug approval |
| Orphan-drug relevance |
Tuberculosis products can qualify for special regulatory treatment depending on the product and indication |
| Current development status |
Mature product class with limited active innovation |
| Biologic exclusivity |
Not applicable |
| Interchangeability |
Governed by small-molecule generic and product-specific requirements, not biosimilar rules |
Regulatory status varies materially by product and country. A sodium salt marketed outside the United States may not have the same label, dosage form or approval history as a U.S. aminosalicylic acid product.
What is the Orange Book status of aminosalicylate sodium?
Aminosalicylate sodium does not have the commercial Orange Book profile of a major branded product with a large, active patent thicket. The relevant U.S. records should be reviewed at the product level because listings may appear under aminosalicylic acid, a specific manufacturer, or a particular dosage form rather than under the sodium-salt name.
No widely recognized active Orange Book patent estate is associated with aminosalicylate sodium as a platform technology. Any remaining exclusivity is more likely to arise from:
- Product-specific formulation claims.
- Manufacturing know-how.
- Regulatory exclusivity attached to a particular product.
- Local registration rights.
- Distribution or procurement contracts.
What patents protect aminosalicylate sodium?
The active ingredient is an old compound and is not expected to have meaningful composition-of-matter patent protection. Commercial protection, where it exists, is more likely to concern formulation, release characteristics, manufacturing process or packaging.
Patent categories
| Patent category |
Likely commercial relevance |
| Composition of matter |
Generally expired or unavailable because PAS is an old active ingredient |
| Delayed-release formulation |
Potentially relevant for products that protect PAS from degradation or improve gastrointestinal delivery |
| Salt selection |
Usually weak for an old, pharmaceutically conventional salt unless tied to a novel technical effect |
| Manufacturing process |
May protect yield, purity, particle size or crystallinity, but is difficult to enforce against independently developed processes |
| Method of treatment |
Possible in some jurisdictions, with limited enforceability for generic product sales |
| Packaging and stability |
Usually low-value and narrow |
| Combination therapy |
May be relevant only where a specific regimen or patient population is claimed |
There is no apparent basis for treating aminosalicylate sodium as a high-barrier patent market. Any freedom-to-operate analysis must be performed by jurisdiction and dosage form because a delayed-release aminosalicylic acid product can have a different patent position from an immediate-release sodium formulation.
When does aminosalicylate sodium lose exclusivity?
The active ingredient has long since lost composition-of-matter exclusivity. The practical exclusivity question is therefore product-specific.
| Exclusivity type |
Expected position |
| Active-ingredient patent |
Expired |
| Basic salt patent |
Expired or commercially weak |
| Historical formulation patents |
Generally expired or near the end of their useful life |
| Current formulation exclusivity |
Depends on product, country and claim scope |
| Pediatric exclusivity |
Product-specific; no broad global right |
| Orphan exclusivity |
Jurisdiction-specific and dependent on an active qualifying product |
| Regulatory data exclusivity |
May remain relevant in selected countries but is not expected to create a broad global barrier |
A generic manufacturer would usually focus on formulation equivalence, impurity control, stability, bioavailability and regulatory documentation rather than composition-of-matter risk.
Are there Paragraph IV challenges for aminosalicylate sodium?
No major, publicly prominent Paragraph IV litigation campaign is associated with aminosalicylate sodium. The absence of visible litigation is consistent with the drug’s small market, limited branded revenue and mature active ingredient.
A Paragraph IV challenge could still arise against a product-specific delayed-release formulation if:
- The reference product has an active listed patent.
- The generic can establish the required bioequivalence pathway.
- The market size supports litigation costs.
- The patent claims cover a commercially necessary release profile.
The litigation risk is lower for a conventional immediate-release sodium product than for a complex delayed-release formulation. A generic entrant would face greater technical risk in proving bioequivalence for modified-release granules than for a simple oral powder, but the overall commercial incentive remains limited.
What formulation patents protect PAS products?
Formulation protection is the most plausible remaining intellectual-property layer.
Potential claim elements include:
- Enteric or delayed-release granules.
- Polymer coatings that resist gastric conditions.
- Protection from moisture or degradation.
- Particle-size distribution.
- Sachet or unit-dose packaging.
- Taste-masking systems.
- Controlled release in the intestine.
- Stability during storage in high-temperature conditions.
The best-known commercial differentiation in PAS products has historically been delayed release. A delayed-release product can reduce gastric exposure and improve administration compared with unprotected PAS, although tolerability remains a significant issue.
A sodium formulation may also create manufacturing and stability issues. Sodium-containing products can impose packaging, hygroscopicity and dosage-volume requirements that affect both development cost and shelf life.
What manufacturing and intellectual-property barriers exist?
Manufacturing barriers are moderate but not high. PAS is a mature small molecule, and chemical synthesis is established. The main barriers are quality and regulatory execution.
Manufacturing risk factors
- Control of residual solvents and inorganic impurities.
- Consistent salt formation.
- Particle-size and flow characteristics.
- Moisture sensitivity.
- Stability under tropical storage conditions.
- Dose uniformity in granules or powder.
- Compatibility with enteric coating systems.
- Batch-to-batch release performance.
- Validation of analytical methods.
For a conventional sodium product, the manufacturing process is unlikely to block entry by itself. For a delayed-release product, coating performance, dissolution specifications and bioequivalence can materially increase development risk.
What is the market size for aminosalicylate sodium?
Aminosalicylate sodium is a niche tuberculosis market rather than a broad commercial pharmaceutical category. Public company filings generally do not report revenue for the ingredient separately. Procurement is fragmented across national TB programs, hospitals, humanitarian agencies and specialty distributors.
Demand is influenced by:
- The global number of drug-resistant tuberculosis cases.
- National treatment guidelines.
- Availability of bedaquiline and other preferred medicines.
- Drug-resistance patterns.
- Local procurement budgets.
- Use in salvage regimens.
- Availability of competing PAS formulations.
The addressable patient population is a small fraction of global tuberculosis cases. The commercial market is narrower still because PAS is not used in every MDR-TB regimen and is often reserved for situations in which preferred agents are unsuitable.
Market segmentation
| Segment |
Commercial importance |
| National tuberculosis programs |
Highest |
| Hospital procurement |
Moderate |
| Private specialist treatment |
Limited |
| Retail pharmacy |
Very limited |
| Humanitarian procurement |
Episodic but relevant |
| Research use |
Negligible |
| Veterinary use |
Not a material driver |
What is the projected market for aminosalicylate sodium through 2030?
The most defensible projection is a flat-to-declining global market in volume, with possible revenue stability from price, supply and formulation effects. Newer MDR-TB regimens will continue to displace PAS where access permits.
2024-2030 market scenario
| Scenario |
Volume trend |
Revenue trend |
Main assumptions |
| Downside |
Decline of 8% to 12% annually |
Decline of 5% to 10% annually |
Rapid adoption of newer regimens and reduced PAS procurement |
| Base case |
Decline of 3% to 6% annually |
Flat to decline of 3% annually |
Continued salvage use and stable program procurement |
| Upside |
Flat to growth of 3% annually |
Growth of 2% to 6% annually |
Supply shortages of alternatives, expanded resistant-disease use or price increases |
The base case is the most likely. Aminosalicylate sodium should be viewed as a low-growth, procurement-driven product with limited opportunity for premium pricing. A new entrant could obtain commercial traction through reliable supply, competitive tender pricing, regional registration and a better-tolerated formulation. A high-value branded strategy is unlikely.
Which companies are competing in the aminosalicylate sodium market?
Competition is fragmented. The market includes manufacturers of PAS or aminosalicylic acid products, regional generic companies, tuberculosis suppliers and contract manufacturers. The most commercially relevant competitor may be an alternative formulation rather than another sodium-salt brand.
Competitive differentiation is likely to depend on:
- Tender price.
- WHO or national regulatory qualification.
- Reliable supply.
- Shelf life.
- Pediatric or weight-band dosing.
- Packaging.
- Dissolution and bioequivalence.
- Ability to supply low- and middle-income countries.
A supplier with a registered delayed-release product may have an advantage over an unformulated active-ingredient manufacturer. The advantage is commercial and regulatory, not necessarily patent-based.
What patent litigation and settlement agreements affect aminosalicylate sodium?
No major current patent litigation or settlement agreement is broadly associated with aminosalicylate sodium. The limited market reduces the probability of prolonged branded-generic litigation.
Potential disputes would more likely involve:
- Product-specific formulation patents.
- Regulatory exclusivity.
- Contract manufacturing rights.
- Distribution territories.
- Procurement tenders.
- Trade-secret allegations involving coating or process technology.
The absence of prominent litigation does not eliminate jurisdiction-specific risk. It indicates that the category has not generated the revenue exposure normally required to support extensive patent enforcement.
How does aminosalicylate sodium compare with newer MDR-TB drugs?
| Attribute |
Aminosalicylate sodium |
Bedaquiline |
Delamanid |
Pretomanid |
| Drug class |
Older antimycobacterial |
Diarylquinoline |
Nitroimidazole |
Nitroimidazole |
| Position in modern MDR-TB therapy |
Reserve or conditional |
Core regimen component |
Regimen-dependent |
Used in defined combination regimens |
| Dosing burden |
High |
Lower |
Moderate |
Combination-specific |
| Tolerability |
Gastrointestinal burden is significant |
Cardiac monitoring required |
QT monitoring required |
Hepatic and interaction monitoring |
| Patent maturity |
Very mature |
More recent and product-specific |
More recent and product-specific |
More recent and product-specific |
| Commercial outlook |
Flat to declining |
Larger strategic market |
Specialized |
Specialized |
| Biosimilar risk |
None |
None, small molecule |
None, small molecule |
None, small molecule |
PAS retains a role because tuberculosis treatment is individualized. Its clinical utility does not translate into strong market growth because it is usually used when better-positioned drugs cannot be used.
What generic launch risks exist for aminosalicylate sodium?
A generic launch would face moderate technical risk and high commercial risk.
Regulatory risks
- Demonstrating equivalence for a modified-release product.
- Meeting dissolution specifications.
- Establishing stability in the intended packaging.
- Addressing sodium exposure in labeling.
- Securing country-specific tuberculosis registration.
- Obtaining procurement qualification.
Commercial risks
- Small and irregular demand.
- Low tender prices.
- Concentrated government purchasing.
- Inventory expiration.
- Limited private-market prescribing.
- Competition from established PAS products.
- Substitution by newer MDR-TB medicines.
The most viable entry strategy is a low-cost, reliable product aimed at national programs and specialist hospitals. A premium formulation would require a clear tolerability or adherence benefit and supporting clinical evidence.
Key Takeaways
- Aminosalicylate sodium is an old reserve antimycobacterial drug for drug-resistant tuberculosis.
- No meaningful late-stage clinical development program is evident for the sodium salt.
- Current research and treatment guidelines favor newer all-oral MDR-TB regimens.
- Composition-of-matter patent protection is not a commercial barrier.
- Formulation, manufacturing, stability and regulatory execution are the main remaining protection layers.
- No prominent Paragraph IV litigation or settlement activity is associated with the product.
- The market is small, procurement-driven and likely flat to declining through 2030.
- The base-case revenue outlook is stable to modestly negative, with upside tied to supply shortages, regional access and improved formulations.
- Generic entry is technically feasible but commercially unattractive unless the supplier has government-tender access or a differentiated delivery system.
- Biosimilar risk does not apply because aminosalicylate sodium is a small-molecule drug.
FAQs
Is aminosalicylate sodium the same as PAS?
Yes. Aminosalicylate sodium is the sodium salt of para-aminosalicylic acid, commonly abbreviated PAS. Product labels may identify the active ingredient as aminosalicylic acid rather than the sodium salt.
Is aminosalicylate sodium still recommended for MDR-TB?
It can be used in selected individualized regimens, but it is generally less preferred than newer medicines because of tolerability, dosing burden and lower placement in modern treatment algorithms.[1]
Does aminosalicylate sodium have biosimilar competition?
No. Biosimilar rules apply to biological products. Aminosalicylate sodium is a conventional small-molecule drug and is subject to generic-drug requirements.
Is PASER a sodium aminosalicylate product?
PASER is a delayed-release aminosalicylic acid granule product. The commercial product name should not be treated as proof that every market uses the sodium salt or the same formulation technology.[3]
Could a new formulation of aminosalicylate sodium obtain market exclusivity?
A new formulation could obtain jurisdiction-specific patent or regulatory protection if it satisfies applicable novelty, inventive-step and regulatory requirements. Any exclusivity would likely be narrow and product-specific rather than a broad monopoly over PAS.
References
-
World Health Organization. (2022). WHO consolidated guidelines on tuberculosis: Module 4: Treatment - drug-resistant tuberculosis treatment. World Health Organization.
-
U.S. National Library of Medicine. (n.d.). ClinicalTrials.gov: Clinical studies involving tuberculosis and drug-resistant tuberculosis. Retrieved June 2024, from https://clinicaltrials.gov/
-
U.S. Food and Drug Administration. (2019). PASER (aminosalicylic acid) delayed-release granules prescribing information. Jacobus Pharmaceutical Company.
-
World Health Organization. (2023). Global tuberculosis report 2023. World Health Organization.
-
Centers for Disease Control and Prevention. (2024). Tuberculosis: Treatment for drug-resistant tuberculosis disease. U.S. Department of Health and Human Services.
