Aminosalicylic acid - Generic Drug Details

What are the generic drug sources for aminosalicylic acid and what is the scope of freedom to operate?

Aminosalicylic acid is the generic ingredient in three branded drugs marketed by Adaptis, Panray, and Bristol Myers Squibb, and is included in three NDAs. Additional information is available in the individual branded drug profile pages.

Summary for aminosalicylic acid

US Patents:	0
Tradenames:	3
Applicants:	3
NDAs:	3
Drug Master File Entries:	15
Raw Ingredient (Bulk) Api Vendors:	151
Clinical Trials:	29
What excipients (inactive ingredients) are in aminosalicylic acid?	aminosalicylic acid excipients list
DailyMed Link:	aminosalicylic acid at DailyMed

Recent Clinical Trials for aminosalicylic acid

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
MRM Health NV	PHASE2
Tanta University	Early Phase 1
Assistance Publique - Hôpitaux de Paris	Phase 1/Phase 2

See all aminosalicylic acid clinical trials

Medical Subject Heading (MeSH) Categories for aminosalicylic acid

Antitubercular Agents

US Patents and Regulatory Information for aminosalicylic acid

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Panray	PARASAL	aminosalicylic acid	TABLET;ORAL	006811-002	Approved Prior to Jan 1, 1982		DISCN	No	No
Bristol Myers Squibb	REZIPAS	aminosalicylic acid resin complex	POWDER;ORAL	009052-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Panray	PARASAL	aminosalicylic acid	TABLET;ORAL	006811-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Adaptis	PASER	aminosalicylic acid	GRANULE, DELAYED RELEASE;ORAL	074346-001	Jun 30, 1994		RX	No	Yes

Aminosalicylic Acid Market Dynamics and Financial Trajectory

Last updated: September 4, 2026

Aminosalicylic acid, also called para-aminosalicylic acid or PAS, is a mature anti-tuberculosis medicine with limited commercial scale. Its principal modern use is as a reserve drug for multidrug-resistant or rifampicin-resistant tuberculosis when preferred agents cannot be used. The market is constrained by low clinical demand, gastrointestinal toxicity, treatment complexity, and competition from newer oral medicines.

The United States product PASER, a delayed-release granule formulation of aminosalicylic acid, is associated with Jacobus Pharmaceutical Co. The product has no meaningful remaining small-molecule exclusivity barrier. Its commercial value depends more on supply continuity, government procurement, specialist prescribing, and manufacturing reliability than on patent protection.

What is aminosalicylic acid used for?

Aminosalicylic acid is a bacteriostatic antimycobacterial drug used in combination therapy for tuberculosis, particularly drug-resistant disease. It is not generally used as first-line treatment for drug-susceptible tuberculosis.

Attribute	Description
Active ingredient	Para-aminosalicylic acid, also called 4-aminosalicylic acid
Principal indication	Drug-resistant tuberculosis
Common U.S. product	PASER delayed-release granules
U.S. dosage form	4-gram packet
Administration	Oral, mixed with acidic food or beverage
Main clinical limitation	Gastrointestinal intolerance and high pill or packet burden
Commercial category	Mature, low-volume specialty anti-infective
Primary buyers	Specialist pharmacies, hospitals, public-health programs, tuberculosis programs, government tenders

PAS is generally used when other recommended agents are contraindicated, unavailable, or unsuitable. The World Health Organization places greater emphasis on shorter, all-oral regimens containing newer agents such as bedaquiline, pretomanid, linezolid, delamanid, and fluoroquinolones. This reduces the addressable population for PAS [1].

What is the FDA regulatory status of aminosalicylic acid?

PASER is an FDA-approved prescription product under NDA 050829. The product is supplied as delayed-release granules because unprotected PAS has poor palatability and can cause substantial gastrointestinal irritation. The U.S. prescribing information directs patients to mix the granules with acidic food or beverage and not to chew them [2].

The product’s regulatory value lies in its approved formulation, manufacturing controls, labeling, and established use rather than in market exclusivity. PAS is an old active pharmaceutical ingredient with a long history of clinical use.

FDA status and dosage form

Regulatory element	Status
U.S. approval pathway	New Drug Application
Product	PASER
NDA	050829
Form	Delayed-release granules
Strength	4 grams per packet
Reference-product status	Approved branded product
Pediatric positioning	Label includes pediatric dosing information based on body weight
Current commercial role	Reserve treatment for drug-resistant tuberculosis

FDA labeling identifies important risks, including gastrointestinal effects, hepatotoxicity, hypothyroidism, electrolyte abnormalities, and interactions involving renal impairment or other antituberculosis medicines [2].

What patents protect aminosalicylic acid and PASER?

The aminosalicylic acid molecule is long off patent. Any historic composition-of-matter rights for PAS would have expired decades ago. The commercial protection associated with PASER has primarily concerned formulation and product development rather than the active ingredient.

The relevant intellectual-property categories are:

1. Delayed-release or enteric granule formulations.
2. Manufacturing processes that improve stability, dispersibility, or tolerability.
3. Packaging and moisture-control systems.
4. Product-specific regulatory exclusivity, if available.
5. Trademarks and brand recognition.

The Orange Book is the primary U.S. source for patents listed against approved drug products. Public Orange Book records should be reviewed for the current edition because listings can change through delisting, expiration, or administrative updates [3]. PAS does not have the profile of a product protected by a current, high-value composition patent.

Patent strength assessment

Patent category	Strategic strength
Active ingredient	None of commercial significance
Core therapeutic use	Low; use is old and clinically established
Delayed-release formulation	Potentially relevant, but narrow and vulnerable to design-around
Manufacturing process	Potentially important if difficult to replicate
Packaging and stability	Moderate operational value, usually limited exclusionary power
Trademark	Commercial recognition, not generic-blocking protection
Overall estate	Weak as a conventional patent moat; stronger as a regulatory and supply-chain position

A generic applicant could face technical development requirements for a formulation that reproduces delayed release, stability, particle characteristics, and administration instructions. Those issues can raise development costs even when the underlying molecule is unprotected.

When does aminosalicylic acid lose exclusivity?

Aminosalicylic acid already has no meaningful remaining active-ingredient exclusivity. The key distinction is between molecular exclusivity and product availability.

Exclusivity type	Expected position
New chemical entity exclusivity	Expired
Composition patent	Expired
Method-of-use patent	No meaningful modern barrier expected
Formulation patent	Any relevant rights would be product-specific and potentially expired or narrow
Orphan exclusivity	Not a central protection for the current product
Data exclusivity	Expired for this mature medicine
Trademark protection	May continue, but does not prevent generic approval

The commercial question is therefore not when PAS loses exclusivity. It is whether another manufacturer can justify the cost of developing, registering, producing, and distributing a low-volume product.

How many patents cover aminosalicylic acid?

No meaningful patent estate is associated with the active aminosalicylic acid molecule. Current protection, if any, would be evaluated at the product level, including PASER’s delayed-release granules, manufacturing process, and packaging.

The absence of a strong patent barrier does not guarantee rapid generic entry. A generic developer would still need to address:

• Pharmaceutical equivalence.
• Delayed-release performance.
• Stability under controlled storage.
• Patient instructions for mixing the granules.
• Supply of pharmaceutical-grade PAS.
• Regulatory requirements for an abbreviated application or equivalent pathway.
• Commercial access to a small and geographically concentrated market.

Are there Paragraph IV challenges to PASER?

No prominent, widely reported Paragraph IV litigation campaign involving PASER is evident in the public record. That is consistent with the product’s limited market size and the low expected return from challenging an old anti-infective.

A Paragraph IV strategy would require a generic applicant to certify that listed patents are invalid, unenforceable, or not infringed. For PASER, the economic incentive is weaker than for high-revenue chronic medicines because:

• The patient population is small.
• Treatment is concentrated in specialist and public-health channels.
• Pricing can be constrained by tenders.
• Demand varies by tuberculosis-program policy.
• Newer MDR-TB regimens reduce use.
• Manufacturing and quality requirements can be disproportionate to sales potential.

The likely generic-entry risk is therefore operational and commercial rather than litigation-driven.

What formulations are protected by aminosalicylic acid patents?

The most commercially relevant formulation is PASER’s delayed-release granule product. Delayed release is important because PAS can be poorly tolerated and highly unpleasant to ingest in unmodified form.

A competing product would need to establish a comparable delivery profile. Potential design alternatives include:

• Enteric-coated granules.
• Alternative acid-resistant coatings.
• Sachet-based multiparticulate systems.
• Modified-release capsules or tablets.
• Different excipient systems.
• Alternative salts or chemically equivalent presentations, subject to regulatory requirements.

The formulation can create a practical barrier even where patent protection is limited. A manufacturer that produces a cheaper but less tolerable product may not capture specialist or public-health demand.

What is the global market for aminosalicylic acid?

The global PAS market is small relative to markets for first-line tuberculosis medicines and newer MDR-TB products. Its demand is linked to the incidence of drug-resistant tuberculosis and to the proportion of patients who cannot receive preferred medicines.

WHO estimated approximately 10.8 million tuberculosis cases globally in 2023, including about 400,000 cases of multidrug-resistant or rifampicin-resistant tuberculosis [4]. Only a subset of those patients is likely to receive PAS. The drug is generally reserved for individualized regimens, intolerance situations, resistance patterns, or constrained procurement environments.

Market drivers

The main positive demand drivers are:

• Persistent MDR/RR-TB incidence.
• Treatment access expansion in low- and middle-income countries.
• Limited availability of newer medicines in some jurisdictions.
• Drug intolerance or contraindications involving preferred agents.
• Government stockpiling and tuberculosis-program procurement.
• Need for backup drugs during shortages.

Market pressures

The principal negative drivers are:

• WHO preference for shorter, all-oral regimens.
• Poor gastrointestinal tolerability.
• High administration burden.
• Low prescriber preference.
• Competition from bedaquiline-based regimens.
• Greater use of delamanid, linezolid, clofazimine, and pretomanid where available.
• Tender-based pricing.
• Small commercial volumes.

How does aminosalicylic acid compare with newer MDR-TB drugs?

Drug	Role in MDR-TB treatment	Commercial position	Competitive impact on PAS
Aminosalicylic acid	Reserve or individualized treatment	Mature, low-volume	Baseline comparator
Bedaquiline	Core agent in many modern regimens	Higher strategic and commercial value	Strong substitution pressure
Pretomanid	Used in defined combination regimens	Newer, regimen-specific	Reduces need for older reserve drugs
Delamanid	Alternative agent for resistant disease	Specialty product	Substitutes in selected patients
Linezolid	Important companion drug	Generic and branded supply	Often preferred over PAS when tolerable
Clofazimine	Companion agent in resistant disease	Established but indication-dependent	Reduces reliance on PAS
Cycloserine	Reserve companion drug	Mature generic market	More direct older-generation comparator

PAS retains value as a backup drug, but its clinical position has weakened as evidence-based MDR-TB regimens have improved [1, 5].

What is the financial trajectory for aminosalicylic acid?

Public financial reporting does not provide a standalone revenue series for PASER or global aminosalicylic acid sales. Jacobus Pharmaceutical is a private company, and PASER revenue is not separately disclosed in public company filings comparable to those available for large pharmaceutical manufacturers.

The likely financial trajectory is mature and structurally constrained:

1. Historical development and regulatory costs have largely been absorbed.
2. Current revenue is dependent on a narrow patient population.
3. Unit economics may be supported by specialty distribution and limited competition.
4. Total revenue is capped by declining clinical use and tender procurement.
5. Manufacturing continuity may be more important than volume growth.
6. Margin volatility can result from small batches, quality controls, and inventory requirements.

Revenue exposure

PASER is unlikely to be a material revenue contributor to a diversified pharmaceutical company. For a small specialist manufacturer, however, it can have strategic value because the product occupies a recognized niche with limited supplier depth.

The financial profile is best characterized as:

Metric	Assessment
Market size	Small
Growth rate	Flat to declining in mature markets
Demand volatility	Moderate to high
Pricing power	Limited in government tenders; potentially higher in constrained specialty channels
Gross-margin potential	Potentially favorable at specialty prices, but offset by low volume
Manufacturing risk	Meaningful
Patent leverage	Low
Generic-entry threat	Moderate in theory, low in near-term commercial attractiveness
Long-term outlook	Stable niche or gradual decline

Which companies are challenging aminosalicylic acid?

No major branded pharmaceutical company is publicly associated with an aggressive, high-value challenge to PASER. Competition is more likely to come from:

• Regional generic manufacturers.
• Government-supplied products.
• Tuberculosis-focused public-health procurement programs.
• Manufacturers of alternative MDR-TB agents.
• Contract manufacturers supplying national tuberculosis programs.

The market is fragmented by geography. A company may be commercially relevant in one country through a government tender without holding a significant global position.

What generic launch scenarios exist for PAS?

Scenario 1: No material new U.S. entrant

This is the most commercially plausible scenario if expected sales do not justify formulation and regulatory costs. PASER remains available through its existing manufacturer or specialty distribution network.

Scenario 2: Regional generic entry

A generic or public-sector product enters selected markets where procurement volumes are sufficient. This would create localized price pressure without materially changing the U.S. market.

Scenario 3: Shortage-driven entry

A supply interruption or discontinuation creates an incentive for another manufacturer to seek approval or import authorization. This scenario depends on regulatory flexibility and the duration of the shortage.

Scenario 4: Reformulated replacement

A competitor develops a more tolerable or easier-to-administer formulation. Such a product could compete on adherence and clinical utility rather than price alone.

What manufacturing and intellectual-property barriers affect the market?

The main barriers are technical and logistical:

• Reliable synthesis or sourcing of pharmaceutical-grade PAS.
• Control of degradation and moisture sensitivity.
• Consistent delayed-release performance.
• Granule coating and particle-size control.
• Packaging that preserves stability.
• Specialty distribution.
• Small-batch manufacturing economics.
• Regulatory documentation for a low-volume product.
• Procurement qualification in tuberculosis programs.

These barriers can protect the incumbent commercially without creating a legally strong patent monopoly. The result is a market with low formal exclusivity but limited practical competition.

Key Takeaways

• Aminosalicylic acid is a mature reserve treatment for drug-resistant tuberculosis.
• PASER is the principal recognized U.S. delayed-release formulation.
• The active ingredient has no meaningful remaining composition-of-matter exclusivity.
• The commercial moat is based on formulation know-how, regulatory status, supply reliability, and specialist distribution.
• Public sources do not disclose standalone PASER revenue.
• Demand is constrained by newer MDR-TB regimens and poor tolerability.
• Generic entry is legally feasible but commercially unattractive at large scale.
• The product’s financial trajectory is likely stable-to-declining, with potential value as a niche supply asset.
• Government procurement, shortages, and regional treatment guidelines will drive revenue more than patent litigation.
• The main investment risk is market erosion and supply economics, not a major Paragraph IV challenge.

FAQs

Is aminosalicylic acid still recommended for tuberculosis?

Yes. It remains available as a reserve or individualized treatment option, but it is generally not preferred when newer, better-tolerated MDR-TB regimens are suitable.

Is PASER a generic drug?

PASER is an approved branded product containing an old active ingredient. Its formulation and product approval distinguish it from unbranded or regionally supplied PAS products.

Does aminosalicylic acid have biosimilar risk?

No. Biosimilar regulation applies to biological products. Aminosalicylic acid is a conventional small-molecule drug. Its competitive risk comes from generic and alternative anti-tuberculosis products.

Can aminosalicylic acid be used alone?

No. Tuberculosis treatment requires combination therapy. Using PAS alone creates a high risk of treatment failure and resistance selection.

What is the main investment risk for PASER?

The principal risk is declining utilization as tuberculosis programs adopt newer all-oral MDR-TB regimens. Low volume, tender pricing, and manufacturing concentration create additional financial risk.

References

1. World Health Organization. (2022). WHO consolidated guidelines on tuberculosis: Module 4: Treatment - Drug-resistant tuberculosis treatment. Geneva, Switzerland: World Health Organization.

2. U.S. Food and Drug Administration. (2016). PASER (aminosalicylic acid) delayed-release granules prescribing information. Silver Spring, MD: FDA.

3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. Silver Spring, MD: FDA.

4. World Health Organization. (2024). Global tuberculosis report 2024. Geneva, Switzerland: World Health Organization.

5. World Health Organization. (2024). WHO consolidated guidelines on tuberculosis: Module 4: Treatment - Drug-resistant tuberculosis treatment, 2024 update. Geneva, Switzerland: World Health Organization.