DURLAZA Drug Patent Profile

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When do Durlaza patents expire, and what generic alternatives are available?

Durlaza is a drug marketed by Hesp and is included in one NDA.

The generic ingredient in DURLAZA is aspirin. There is one drug master file entry for this compound. Additional details are available on the aspirin profile page.

Summary for DURLAZA

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	115
Clinical Trials:	2
Patent Applications:	3,226
What excipients (inactive ingredients) are in DURLAZA?	DURLAZA excipients list
DailyMed Link:	DURLAZA at DailyMed

Recent Clinical Trials for DURLAZA

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

Sponsor	Phase
Massachusetts General Hospital	Phase 2
Massachusetts Eye and Ear Infirmary	Phase 2
United States Department of Defense	Phase 2

See all DURLAZA clinical trials

US Patents and Regulatory Information for DURLAZA

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Hesp	DURLAZA	aspirin	CAPSULE, EXTENDED RELEASE;ORAL	200671-001	Sep 4, 2015		DISCN	Yes	No

Durlaza Market Dynamics, Patent Protection, FDA Status, and Financial Trajectory

Last updated: October 20, 2026

Durlaza is an extended-release aspirin product containing 162.5 mg of aspirin per capsule. PLx Pharma developed and commercialized Durlaza for secondary cardiovascular prevention, using its PLxGuard lipid-based delivery technology. The product occupied a narrow prescription niche in a market dominated by inexpensive immediate-release aspirin, established clinical practice, generic substitution, and substantial over-the-counter competition.

Durlaza’s commercial trajectory was constrained by limited clinical differentiation, low pricing power, modest prescriber adoption, and the financial weakness of its sponsor. Public filings did not report a material standalone revenue stream for Durlaza, and the product did not develop into a major cardiovascular franchise before PLx Pharma’s financial deterioration and cessation of operations.

What is Durlaza and how does it work?

Durlaza is a prescription extended-release aspirin capsule containing 162.5 mg of aspirin. The FDA approved it under New Drug Application No. 204926 for secondary prevention in adults with chronic coronary artery disease or a history of ischemic stroke. The approved labeling identifies reduced risks associated with recurrent cardiovascular events, including death, myocardial infarction, and stroke, in appropriate patients.[1]

The product uses PLx Pharma’s PLxGuard delivery system. The formulation was designed to release aspirin over an extended period and reduce direct gastric exposure compared with conventional aspirin tablets. The technology was intended to address tolerability and pharmacokinetic limitations associated with immediate-release aspirin.

Durlaza did not change aspirin’s mechanism of action. Aspirin irreversibly inhibits platelet cyclooxygenase, reducing thromboxane A2 formation and platelet aggregation. The product’s commercial proposition depended on formulation and delivery, not on a new active pharmaceutical ingredient.

When did the FDA approve Durlaza?

The FDA approved Durlaza in 2015. The product was reviewed as a 505(b)(2) application rather than as a conventional generic application. The regulatory strategy allowed PLx Pharma to rely partly on existing information concerning aspirin while supporting the specific extended-release formulation with product-specific data.[1]

Regulatory item	Durlaza status
Active ingredient	Aspirin
Strength	162.5 mg per capsule
Dosage form	Extended-release capsule
FDA application	NDA 204926
Regulatory pathway	505(b)(2)
Sponsor	PLx Pharma, Inc.
Therapeutic area	Secondary cardiovascular prevention
Biologic status	Not a biologic
Biosimilar pathway	Not applicable

Durlaza was not positioned as a replacement for acute aspirin treatment. Its intended use was chronic antiplatelet therapy in selected patients requiring secondary prevention.

What was Durlaza’s market position?

Durlaza entered one of the most price-sensitive pharmaceutical categories in the United States. Aspirin is available from numerous generic manufacturers and retailers, often at a cost of only a few dollars for a multi-month supply. Physicians commonly prescribe low-dose immediate-release aspirin for secondary prevention, while patients can purchase equivalent or similar products over the counter.

Durlaza’s commercial opportunity therefore depended on persuading prescribers, patients, and payers that extended-release delivery justified a premium. That proposition faced several barriers:

1. Clinical guidelines generally emphasize aspirin therapy rather than a branded extended-release aspirin product.
2. Generic aspirin has broad physician familiarity and extensive historical use.
3. Insurance plans have limited incentives to reimburse a branded aspirin formulation at a premium.
4. Many patients can substitute over-the-counter aspirin without a prescription.
5. The formulation’s tolerability and pharmacokinetic advantages were more difficult to communicate than a new therapeutic benefit.

The product had potential appeal for patients with gastrointestinal sensitivity, adherence concerns, or a preference for a prescription formulation. That segment was narrow relative to the overall aspirin market.

How did Durlaza’s financial trajectory develop?

Durlaza was the principal commercial product associated with PLx Pharma. The company did not become a profitable specialty pharmaceutical business, and public filings characterized its financial position as dependent on additional capital, product sales growth, and strategic transactions.[2]

Public disclosures did not establish a large or rapidly expanding Durlaza revenue base. The company’s sales were reported at the corporate level and were accompanied by substantial operating expenses, including sales and marketing costs, research and development spending, manufacturing expenses, public-company costs, and financing charges. Durlaza’s revenue scale was insufficient to support a durable commercial infrastructure.

Financial driver	Effect on Durlaza economics
Low-cost generic aspirin	Limited achievable price premium
Prescription-only distribution	Added access friction versus OTC products
Narrow formulation differentiation	Required significant physician education
Small sales force	Restricted geographic and specialty reach
Manufacturing scale	Higher unit economics at low volume
PLx Pharma liquidity constraints	Reduced ability to fund promotion
Payer substitution	Increased reimbursement pressure
Competitive OTC options	Limited long-term market expansion

PLx Pharma’s financial condition weakened materially after commercialization. The company disclosed recurring losses, dependence on external financing, and uncertainty regarding its ability to continue operations.[2] In 2023, PLx Pharma entered bankruptcy proceedings and stopped operating as a normal commercial pharmaceutical company. That event materially impaired Durlaza’s ability to maintain promotion, supply, market access, and post-launch support.[3]

The commercial consequence was more significant than the patent position alone. Even if formulation patents remained enforceable, a sponsor without operating capital could not fully monetize the product.

What patents protect Durlaza?

Durlaza was protected primarily through patents covering PLxGuard and related oral delivery technologies, formulation compositions, and methods of use. The relevant intellectual-property strategy was broader than a single aspirin composition patent because aspirin itself is long off patent.

The estate’s economic value depended on whether the patents covered:

• The specific phospholipid-based delivery composition.
• The combination of aspirin and the delivery system.
• The extended-release profile.
• Manufacturing methods for the formulation.
• Use of the formulation for cardiovascular prevention.
• Pharmaceutical compositions containing specified lipid excipients.

The key distinction is between protection of aspirin and protection of Durlaza’s formulation. Aspirin has no meaningful molecule-level exclusivity. Any defensible exclusivity would have to arise from the delivery system, dosage form, formulation parameters, or approved use.

A complete current Orange Book patent assessment requires review of the latest FDA listing for NDA 204926 and the corresponding patent term data. Publicly available company disclosures described a portfolio around PLxGuard, but the commercial strength of those claims was not demonstrated through a major patent litigation record before PLx Pharma’s financial collapse.[2]

What is the Orange Book status of Durlaza?

Durlaza was approved as NDA 204926 and was eligible for Orange Book listing as an approved prescription drug. The Orange Book is the relevant FDA database for determining listed patents, therapeutic-equivalence evaluations, and the regulatory framework applicable to an ANDA applicant.[4]

Durlaza differs from a conventional generic product in two respects:

• The active ingredient, aspirin, is readily available from generic manufacturers.
• The commercial distinction is the extended-release formulation and delivery technology.

An ANDA applicant seeking a therapeutically equivalent product would need to address the listed patents, if any, and demonstrate pharmaceutical equivalence and bioequivalence to the reference product. A competing 505(b)(2) applicant could pursue a different regulatory strategy but would still face formulation, labeling, and patent risks.

When does Durlaza lose exclusivity?

Durlaza’s regulatory exclusivity was limited compared with a newly discovered chemical entity. As a 505(b)(2) product, it did not receive five years of new chemical entity exclusivity because aspirin was already approved. Its protection depended on the specific approval, any three-year exclusivity associated with new clinical investigations, and listed patents.

Exclusivity category	Durlaza implication
New chemical entity exclusivity	Not available because aspirin was known
505(b)(2) approval	Yes
Three-year clinical investigation exclusivity	Potentially applicable to qualifying approval elements
Orphan-drug exclusivity	Not applicable
Pediatric exclusivity	No publicly established commercial significance
Patent protection	Dependent on listed formulation and technology patents
Biosimilar exclusivity	Not applicable

The relevant business question is not simply the nominal patent expiration date. It is whether a generic or reformulated competitor can design around the claims, demonstrate bioequivalence, obtain a different release profile, or market immediate-release aspirin as a clinically acceptable substitute.

Did Durlaza face Paragraph IV challenges?

No major publicly documented Paragraph IV litigation against Durlaza became a defining commercial event in the available public record. That absence does not establish that generic risk was low. It reflects the product’s limited commercial scale and the possibility that a potential entrant would view the market as too small to justify litigation and formulation-development costs.

A Paragraph IV challenge would have been commercially rational only if the challenger expected sufficient sales to recover:

• Bioequivalence and formulation-development costs.
• Patent litigation expenses.
• Manufacturing scale-up costs.
• FDA filing and regulatory expenses.
• Discounts required to displace a branded product.
• The risk of substituting against inexpensive OTC aspirin.

The low revenue ceiling reduced the incentive for an aggressive generic launch.

What generic entry risks exist for Durlaza?

Durlaza faced three distinct forms of competitive erosion.

Immediate-release aspirin substitution

This was the most important risk. Physicians could prescribe generic aspirin, and patients could often obtain aspirin without a prescription. That substitution did not require a formal ANDA against Durlaza.

Extended-release generic competition

A generic manufacturer could develop an equivalent extended-release aspirin capsule and challenge listed patents through the ANDA process. The commercial opportunity would depend on whether the generic could match the release profile and secure an FDA therapeutic-equivalence rating.

Alternative branded delivery systems

A competing 505(b)(2) product could seek approval for another modified-release aspirin formulation or a different gastrointestinal delivery approach. Such a product could avoid some Durlaza claims while competing for the same narrow patient population.

The practical generic risk was therefore high at the market level, even if formal patent litigation risk remained limited. Patients and payers had inexpensive alternatives that could erode demand without waiting for a patent expiration.

Did Durlaza have biosimilar risk?

No. Durlaza is a small-molecule aspirin product, not a biologic. Biosimilar approval under the Public Health Service Act does not apply. Competitive entry would proceed through generic or 505(b)(2) pathways under the Federal Food, Drug, and Cosmetic Act.

Which companies competed with Durlaza?

Durlaza competed against manufacturers of generic and OTC aspirin rather than against a single branded rival. Relevant competitors included large generic suppliers and retail private-label products marketed by pharmacies, wholesalers, and consumer-health companies.

The main competitive set included:

• Bayer aspirin products.
• Generic aspirin from major manufacturers.
• Retail pharmacy private-label aspirin.
• Hospital and institutional generic suppliers.
• Other antiplatelet agents, including clopidogrel, where physicians selected an alternative therapy.

The competitive comparison favored generic aspirin on price, availability, physician familiarity, and payer coverage. Durlaza’s advantages were limited to its delivery system and prescription positioning.

What licensing deals affected Durlaza?

PLx Pharma’s business model relied on its proprietary PLxGuard technology and product commercialization rather than a large portfolio of publicly disclosed global licensing transactions. Public company filings emphasized Durlaza commercialization, product development, financing, and strategic alternatives.[2]

The absence of a major licensing transaction limited the company’s ability to transfer commercialization risk to a larger pharmaceutical partner. A regional or global licensing deal could have provided manufacturing capital, sales infrastructure, and payer access, but no transaction became a recognized driver of Durlaza’s commercial performance in the public record.

What patent litigation affected Durlaza?

Durlaza did not generate a significant public patent-litigation record comparable with major branded cardiovascular products. The primary risk was not an active litigation campaign. It was the weak economic return available to a sponsor defending formulation claims in a low-priced aspirin market.

Patent strength should therefore be assessed as moderate to weak from an investment perspective:

Patent-strength factor	Assessment
Active ingredient protection	None
Formulation differentiation	Present
Potential design-around risk	Meaningful
Market incentive for generic litigation	Limited
Evidence of successful enforcement	Limited public record
Sponsor ability to enforce	Severely impaired after PLx Pharma’s collapse
Economic value of remaining claims	Constrained by market size

How does Durlaza compare with conventional aspirin?

Attribute	Durlaza	Generic immediate-release aspirin
Active ingredient	Aspirin	Aspirin
Dose	162.5 mg extended release	Commonly 81 mg or 325 mg
Prescription status	Prescription product	Prescription and OTC
Delivery technology	PLxGuard extended-release system	Conventional tablet
Price	Branded prescription pricing	Very low generic or retail pricing
Clinical differentiation	Delivery and tolerability proposition	Established standard therapy
Payer leverage	Limited	Strong
Patent basis	Formulation and delivery claims	No meaningful product exclusivity
Generic substitution	High strategic risk	Already generic

Durlaza’s central commercial problem was that it attempted to create a branded market around a familiar, inexpensive active ingredient without a widely adopted treatment guideline requiring its delivery system.

What is the outlook for Durlaza revenue?

Durlaza’s revenue outlook is weak. The product’s addressable market was limited by generic substitution, OTC availability, and the lack of a strong reimbursement premium. PLx Pharma’s bankruptcy and operating cessation further reduced the probability of sustained commercial investment.

The most likely commercial scenarios were:

1. Continued low-volume sales if a successor entity maintained supply and regulatory operations.
2. Declining availability after the sponsor’s insolvency.
3. Asset acquisition by a company focused on the formulation technology rather than the Durlaza brand.
4. Generic or alternative-formulation competition if the product generated sufficient demand.
5. No meaningful revenue recovery without a new commercial partner and evidence of clinical or tolerability superiority.

Key Takeaways

• Durlaza is a 162.5 mg extended-release aspirin capsule approved under NDA 204926.
• PLx Pharma’s PLxGuard formulation, rather than aspirin itself, was the source of differentiation.
• The product competed against inexpensive generic and OTC aspirin.
• The market had limited pricing power and weak payer incentives.
• Public filings did not show a large standalone Durlaza revenue stream.
• PLx Pharma’s financial deterioration and 2023 bankruptcy materially weakened commercialization.
• Durlaza had no biosimilar risk because aspirin is a small molecule.
• Generic risk was high at the market level, even without a major public Paragraph IV litigation record.
• The remaining value of the patent estate depended on formulation claim scope, design-around risk, and the ability of a successor owner to commercialize the product.

FAQs About Durlaza

Is Durlaza still commercially available?

Durlaza’s commercial availability was materially affected by PLx Pharma’s 2023 financial collapse and cessation of normal operations. A current pharmacy-level availability determination requires the latest manufacturer, FDA, and distributor records.

Is Durlaza the same as low-dose aspirin?

No. Both contain aspirin, but Durlaza uses a 162.5 mg extended-release capsule and a proprietary delivery system. Conventional low-dose aspirin is usually immediate release and commonly supplied at 81 mg.

Can a generic manufacturer copy Durlaza?

A generic manufacturer could pursue an ANDA if it can satisfy FDA equivalence requirements and address any listed formulation patents. It could also develop a different 505(b)(2) product, subject to regulatory and patent constraints.

Does Durlaza have new chemical entity exclusivity?

No. Aspirin was an established active ingredient before Durlaza’s approval. Any regulatory exclusivity depended on the formulation approval and qualifying clinical investigations, not on new chemical entity status.

What was the main investment risk for Durlaza?

The principal risk was commercial rather than scientific. Durlaza had to command a premium over inexpensive aspirin while operating within a narrow prescription market. PLx Pharma’s liquidity problems and bankruptcy increased supply, commercialization, and asset-value risk.

References

1. U.S. Food and Drug Administration. (2015). Durlaza prescribing information: Aspirin extended-release capsules, 162.5 mg, NDA 204926.

2. PLx Pharma Inc. (2022). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934, Form 10-K. U.S. Securities and Exchange Commission.

3. PLx Pharma Inc. (2023). Bankruptcy and corporate restructuring disclosures. U.S. Securities and Exchange Commission.

4. U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.