List of Excipients in Branded Drug DURLAZA

Company	Tradename	Ingredient	NDC	Excipient	Potential Generic Entry
New Haven Pharmaceuticals Inc	DURLAZA	acetylsalicylic acid	58487-001	CASTOR OIL
New Haven Pharmaceuticals Inc	DURLAZA	acetylsalicylic acid	58487-001	ETHYLCELLULOSES
New Haven Pharmaceuticals Inc	DURLAZA	acetylsalicylic acid	58487-001	GELATIN

Durlaza Excipient Strategy and Commercial Opportunities

Last updated: August 15, 2026

Durlaza is a 162.5 mg extended-release aspirin capsule developed for once-daily antiplatelet therapy. Its commercial value is tied to modified-release performance, gastrointestinal tolerability, manufacturing consistency, and differentiation from low-cost immediate-release aspirin. The strongest excipient opportunities are controlled-release matrices, multiparticulate systems, capsule engineering, and lower-cost reformulation pathways rather than new active-ingredient protection.

What is Durlaza and how does its formulation work?

Durlaza contains aspirin, also known as acetylsalicylic acid, in an extended-release oral capsule. The product is designed to deliver aspirin over an extended period rather than producing the rapid exposure profile associated with conventional immediate-release tablets.

Product attribute	Durlaza
Active ingredient	Aspirin
Strength	162.5 mg
Dosage form	Extended-release capsule
Route	Oral
FDA application	NDA 207625
Sponsor	New Haven Pharmaceuticals
Therapeutic category	Antiplatelet therapy
Commercial positioning	Once-daily extended-release aspirin
Regulatory pathway	505(b)(2)-type reformulation strategy
Primary formulation issue	Controlling aspirin release while limiting degradation and gastrointestinal exposure

The FDA-approved indication covers reduction of the risk of death and nonfatal myocardial infarction in patients with a history of myocardial infarction or unstable angina, and reduction of recurrent stroke risk in certain patients with prior ischemic stroke or transient ischemic attack.[1]

Aspirin presents a difficult formulation problem. It is susceptible to hydrolysis, particularly in the presence of moisture, and its dissolution can change with particle size, compression force, excipient grade, coating thickness, and storage conditions. A sustained-release design must control release without creating excessive variability between patients.

What excipients are strategically important for Durlaza?

The most important excipient functions are release control, moisture management, powder flow, capsule filling, mechanical protection, and stability. The exact qualitative and quantitative composition should be taken from the approved product label and regulatory filings rather than inferred from generic excipient databases.

Release-controlling polymers

Hydrophilic and hydrophobic polymers can slow aspirin release through different mechanisms.

Excipient class	Formulation role	Commercial benefit	Main risk
Ethylcellulose	Hydrophobic diffusion barrier	Predictable sustained release and scalable coating	Organic-solvent processing or coating variability
Hypromellose	Hydrophilic gel matrix	Broad supplier base and aqueous processing options	Swelling and food-dependent release
Methacrylate copolymers	pH-dependent or pH-independent coating	Enables targeted intestinal release	Greater process and regulatory complexity
Polyvinyl acetate systems	Matrix release control	Strong mechanical robustness	Supplier and grade dependence
Lipid or wax excipients	Diffusion barrier	Low-cost release modification	Batch-to-batch dissolution variability
Crosslinked polymers	Porosity and release control	Can improve multiparticulate performance	Limited suitability at high loading

For a Durlaza follow-on, ethylcellulose and hypromellose are commercially attractive because they have established pharmaceutical supply chains and extensive regulatory precedent. The preferred design depends on whether the target is an exact pharmaceutical equivalent, an improved product, or a lower-cost 505(b)(2) formulation.

Moisture-control excipients

Moisture is a central stability risk for aspirin. Excipients with low moisture content and low hygroscopicity can reduce hydrolysis during manufacture and storage.

Potential strategies include:

• Selecting low-moisture grades of microcrystalline cellulose, lactose, or starch.
• Using anhydrous or directly compressible excipients where compatible with the process.
• Minimizing aqueous granulation.
• Applying a protective film or barrier coating.
• Using high-barrier blister packaging or desiccant-equipped bottles.
• Controlling capsule-shell water activity.
• Establishing tight incoming specifications for excipient loss on drying and water activity.

A low-water-activity formulation can create a stronger product than a nominally identical formulation made with hygroscopic excipients. This advantage may support a formulation patent if the relationship between excipient moisture, aspirin degradation, and release performance is demonstrated experimentally.

Flow and capsule-filling excipients

Extended-release capsules require consistent powder or pellet filling. Useful excipient functions include:

• Flow improvement through colloidal silicon dioxide.
• Lubrication with magnesium stearate or comparable materials.
• Bulk management with microcrystalline cellulose.
• Granule binding with povidone or hypromellose.
• Density adjustment to achieve capsule-weight uniformity.
• Segregation control during high-speed filling.

Magnesium stearate concentration and blending time require particular control. Excessive lubrication can reduce wettability and alter dissolution. Under-lubrication can produce filling defects, sticking, and capsule-weight variability.

What formulation approaches can improve Durlaza?

Three formulation platforms provide the clearest commercial opportunities.

Multiparticulate extended-release capsules

Pellets or coated granules filled into a hard capsule offer several advantages:

• Better control of dose distribution.
• Reduced sensitivity to local gastrointestinal conditions.
• Lower risk that a single dosage unit will release the entire dose prematurely.
• Easier adjustment of release through coating thickness and polymer composition.
• Potential for combining immediate-release and extended-release populations.

A multiparticulate design may be commercially attractive if it provides lower dissolution variability than a single matrix plug. The principal development burden is coating-process control, including particle-size distribution, spray rate, inlet temperature, atomization, curing, and residual solvent management.

Hydrophobic matrix capsules

A hydrophobic matrix can delay aspirin dissolution without requiring a separate enteric layer. This approach can reduce process steps and lower manufacturing cost. The main risks are poor reproducibility at low drug loading, incomplete release, and sensitivity to food and gastrointestinal motility.

Hybrid immediate-release and extended-release systems

A capsule containing a small immediate-release fraction and a controlled-release fraction could provide faster onset with prolonged exposure. This design may appeal to patients who want once-daily administration but could require a new pharmacokinetic and clinical justification.

A hybrid product is more likely to require a 505(b)(2) pathway than a straightforward ANDA, depending on the extent of formulation and labeling differences.

What patent protection applies to Durlaza and its excipients?

Durlaza's commercial protection is primarily formulation-based. Aspirin itself is an old, off-patent active ingredient. Any enforceable value would therefore depend on claims directed to:

• Extended-release aspirin compositions.
• Specific polymer systems.
• Coated particles or pellets.
• Release profiles.
• Stability under defined moisture conditions.
• Capsule architecture.
• Manufacturing processes.
• Therapeutic use of a controlled-release aspirin product.

The relevant patent estate should be separated into three categories:

Protection category	Relevance to Durlaza
Active-ingredient patents	No meaningful protection for aspirin
Formulation patents	Potentially important if claims cover the release mechanism or composition
Method-of-use patents	Potentially relevant to cardiovascular or cerebrovascular indications, but difficult to enforce against label-neutral generic use

An Orange Book listing, patent term, terminal disclaimer, pediatric extension, and litigation history must be evaluated against the current FDA Orange Book record and the underlying patent documents. The FDA label confirms the approved product and application, but it does not by itself establish the complete patent position.[1]

When does Durlaza lose exclusivity?

Durlaza received FDA approval in 2015. Any new-drug exclusivity associated with the application would have been time-limited and is no longer the principal commercial barrier. Aspirin has no meaningful active-ingredient exclusivity.

The commercial question is therefore whether a current formulation patent, listed patent, regulatory exclusivity period, or litigation settlement restricts generic entry. For an old aspirin product, the practical entry barriers are more likely to be:

1. Demonstrating pharmaceutical equivalence.
2. Matching the extended-release dissolution profile.
3. Establishing bioequivalence.
4. Managing aspirin degradation.
5. Proving manufacturing consistency.
6. Securing reliable low-cost excipient supply.

A generic applicant would typically evaluate an ANDA if it can match the reference product's dosage form, strength, route, release characteristics, labeling, and inactive-ingredient requirements. A materially different release mechanism or clinical claim could move the product toward a 505(b)(2) application.

What is the FDA regulatory status of Durlaza?

Durlaza was approved as an extended-release aspirin capsule under NDA 207625. The product's regulatory value is based on the extended-release dosage form rather than a novel active ingredient.[1]

FDA regulatory considerations for a follow-on product

A competing product would need to address:

• Aspirin assay and degradation products.
• Dissolution across multiple pH conditions.
• Release performance after alcohol exposure.
• Fed and fasted pharmacokinetics.
• Dose-dumping risk.
• Capsule-shell compatibility.
• Stability under accelerated and long-term conditions.
• Comparative bioavailability.
• Labeling for cardiovascular and cerebrovascular risk reduction.

Alcohol-induced dose dumping is a major concern for modified-release oral products. A formulation that performs adequately in standard dissolution media but releases aspirin rapidly in high-alcohol media may face regulatory resistance.

How strong is the formulation patent estate for Durlaza?

Durlaza's formulation patent strength depends on claim scope and claim construction, not on the use of aspirin alone. Broad claims covering any extended-release aspirin formulation would face substantial validity and obviousness pressure because sustained-release aspirin, polymer matrices, and coated particles are established technologies.

Stronger claim positions would require a technically specific combination, such as:

• A defined aspirin-to-polymer ratio.
• A narrow dissolution window.
• A demonstrated reduction in degradation.
• A specific multiparticulate architecture.
• A controlled relationship between moisture content and release.
• A manufacturing parameter that produces a reproducible product attribute.

Method-of-use claims are generally weaker against generic competition when the active ingredient is widely used and the generic label omits a protected indication. Formulation claims can be more valuable because they directly address the product that an ANDA applicant must manufacture.

Which companies could challenge Durlaza commercially?

The relevant competitive set includes:

• Generic aspirin manufacturers.
• Contract development and manufacturing organizations with multiparticulate capabilities.
• Cardiovascular companies with low-dose aspirin portfolios.
• Developers of gastroprotective aspirin products.
• Companies commercializing alternative antiplatelet agents.

Potential generic competition would likely come from large manufacturers with established oral-solid-dose platforms. The product's low active-ingredient cost limits the commercial incentive unless the competitor can manufacture the extended-release dosage form efficiently or bundle it into a broader cardiovascular portfolio.

The principal alternatives include immediate-release aspirin, enteric-coated aspirin, clopidogrel, ticagrelor, and other antiplatelet therapies. Durlaza's differentiation is convenience and release control, not superior antiplatelet pharmacology.

What commercial opportunities exist for Durlaza excipient technology?

Lower-cost generic or authorized-generic product

The most direct opportunity is a compliant extended-release aspirin capsule using standard polymers and high-barrier packaging. Cost reduction could come from:

• Eliminating unnecessary coating layers.
• Using aqueous polymer dispersions.
• Improving capsule-filling speed.
• Reducing excipient overage.
• Selecting dual-function excipients.
• Using a common polymer platform across multiple strengths.

The commercial ceiling is limited by the low price of conventional aspirin. A successful product needs a meaningful manufacturing-cost advantage or a differentiated channel strategy.

Gastrointestinal-tolerability positioning

A controlled-release formulation could be positioned around reduced localized aspirin exposure, but clinical claims require supporting evidence. In vitro dissolution differences alone do not establish reduced gastrointestinal injury. A company would need pharmacodynamic, pharmacokinetic, or clinical data that support the proposed benefit.

Combination products

Durlaza-type extended-release aspirin could be combined with cardiovascular agents, subject to compatibility and regulatory requirements. Candidate categories include:

• Statins.
• Antihypertensive drugs.
• Proton-pump inhibitors.
• Other antiplatelet agents.

Combination products could improve adherence but create substantial development complexity. Dose flexibility, drug-drug compatibility, labeling, and separate titration requirements limit the addressable opportunities.

Pediatric or specialized dosage forms

Specialized aspirin dosage forms may include:

• Lower-dose multiparticulates.
• Sprinkle capsules.
• Sachets.
• Modified-release granules.
• Products for patients with swallowing difficulty.

These markets are narrower and may require new clinical and regulatory work. They can still support premium pricing if the dosage form solves a clear administration problem.

Excipient licensing

Excipient suppliers could license:

• Low-moisture direct-compression systems.
• Controlled-release polymer blends.
• Coating platforms.
• Aspirin-stabilizing packaging systems.
• Multiparticulate manufacturing processes.

The strongest licensing model would combine an excipient with process know-how and analytical methods. A commodity polymer alone is unlikely to command substantial value because multiple suppliers and substitutes exist.

What manufacturing and IP barriers affect generic entry?

The key technical barriers are dissolution matching, aspirin stability, and scale-up. A formulation that works at laboratory scale may fail during commercial production because of changes in coating uniformity, granule density, mixing energy, or capsule-fill weight.

High-value manufacturing controls

• Narrow particle-size distribution.
• Controlled coating weight gain.
• In-process moisture monitoring.
• Standardized polymer viscosity.
• Blend-uniformity testing.
• Dissolution testing at multiple pH values.
• Alcohol dose-dumping testing.
• Tight control of capsule-shell moisture.
• Packaging validation under high humidity.

A company that owns the analytical method, process window, and stability data may have a stronger practical barrier than a company holding a broad but vulnerable composition patent.

How does Durlaza compare with immediate-release and enteric-coated aspirin?

Attribute	Immediate-release aspirin	Enteric-coated aspirin	Durlaza
Onset	Fast	Delayed	Controlled over time
Release location	Stomach and intestine	Primarily intestine	Extended release
Manufacturing complexity	Low	Moderate	Moderate to high
Cost of goods	Very low	Low	Higher
Generic competition	Intense	Intense	More technically demanding
Main differentiation	Low price	Gastric protection positioning	Once-daily extended release
Key risk	Gastric irritation	Delayed or variable absorption	Dose dumping and dissolution variability

Durlaza is commercially differentiated from standard aspirin, but its low-cost active ingredient limits price elasticity. The strongest business case is a technically robust product with low manufacturing cost and a clear adherence or tolerability rationale.

What generic launch scenarios exist for Durlaza?

Scenario 1: Direct ANDA competition

A generic applicant matches the capsule strength, release profile, labeling, and bioequivalence requirements. This is the most direct route and would place the greatest pressure on price.

Scenario 2: 505(b)(2) reformulation

A developer introduces a different polymer system, capsule design, or release profile and relies partly on existing aspirin safety and efficacy data. This pathway can support differentiated labeling but normally requires more development work.

Scenario 3: Authorized generic or license transaction

The sponsor or a partner licenses the formulation to a generic manufacturer. This approach monetizes existing development work while expanding manufacturing scale and distribution.

Scenario 4: Premium specialty product

A reformulated product targets patients with adherence, swallowing, or gastrointestinal-tolerability needs. This route requires credible clinical differentiation and a focused commercial channel.

Key Takeaways

• Durlaza is a 162.5 mg extended-release aspirin capsule approved under NDA 207625.
• Its commercial differentiation comes from release control, not from a novel active ingredient.
• The most relevant excipient strategies involve ethylcellulose, hypromellose, methacrylate polymers, low-moisture fillers, and multiparticulate systems.
• Moisture control is central because aspirin is vulnerable to hydrolysis.
• Formulation and manufacturing claims are more commercially relevant than aspirin composition claims.
• A direct generic competitor would likely pursue an ANDA if it can match the reference product's release and bioequivalence profile.
• A materially different formulation would more likely fit a 505(b)(2) strategy.
• The main barriers are dissolution matching, dose-dumping control, stability, capsule filling, and scale-up.
• The best commercial opportunities are lower-cost generic supply, multiparticulate delivery, improved adherence, specialized dosage forms, and excipient-process licensing.
• The addressable market is constrained by the very low cost of immediate-release aspirin and strong competition from established antiplatelet therapies.

FAQs

Can Durlaza be reformulated with a different release-controlling polymer?

Yes. A different polymer system may support an ANDA only if the product satisfies applicable equivalence requirements. A clinically or technically distinct release profile may require a 505(b)(2) application.

Is aspirin degradation mainly an excipient problem?

No. Degradation reflects the interaction of aspirin, water activity, processing conditions, packaging, temperature, and storage time. Excipient selection is one part of the stability strategy.

Would an enteric coating replace Durlaza's extended-release function?

No. Enteric coating primarily delays release until the dosage form reaches a higher-pH intestinal environment. It does not necessarily reproduce an extended-release profile.

Can a Durlaza generic use a different capsule shell?

Potentially. The capsule shell must be compatible with the formulation, preserve stability, meet performance requirements, and satisfy FDA inactive-ingredient and equivalence standards.

Does a Durlaza follow-on product need a new cardiovascular outcomes trial?

A direct generic generally relies on the reference product's established safety and efficacy through the ANDA pathway. A reformulated or newly positioned product may require additional clinical evidence depending on its claims and regulatory pathway.

References

1. U.S. Food and Drug Administration. (2015). Durlaza aspirin extended-release capsules, 162.5 mg: Prescribing information. New Haven Pharmaceuticals.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.

3. U.S. Food and Drug Administration. (2017). Guidance for industry: ANDAs for certain highly variable drug products. FDA.

4. U.S. Food and Drug Administration. (2019). Guidance for industry: Extended release solid oral dosage forms: Development, evaluation, and application of in vitro/in vivo correlations. FDA.

5. U.S. Pharmacopeial Convention. (2024). United States Pharmacopeia and National Formulary. USP.