List of Excipients in Branded Drug ASPIRIN AND DIPYRIDAMOLE

Generic Drugs Containing ASPIRIN AND DIPYRIDAMOLE

Company	Ingredient	NDC	Excipient
Teva Pharmaceuticals USA Inc	aspirin and dipyridamole	0093-3064	ALUMINUM MONOSTEARATE
Teva Pharmaceuticals USA Inc	aspirin and dipyridamole	0093-3064	CELLULOSE, MICROCRYSTALLINE
Teva Pharmaceuticals USA Inc	aspirin and dipyridamole	0093-3064	COPOVIDONE K25-31
Teva Pharmaceuticals USA Inc	aspirin and dipyridamole	0093-3064	D&C YELLOW NO. 10
Teva Pharmaceuticals USA Inc	aspirin and dipyridamole	0093-3064	DIMETHICONE
Teva Pharmaceuticals USA Inc	aspirin and dipyridamole	0093-3064	FD&C BLUE NO. 1

What are the Most Frequently-Used Excipients in ASPIRIN AND DIPYRIDAMOLE?

# Of NDCs	Excipient
2	ACACIA
1	ALUMINUM MONOSTEARATE
2	AMMONIA
2	ANHYDROUS LACTOSE
3	CELLULOSE, MICROCRYSTALLINE
1	COPOVIDONE K25-31

Aspirin and Dipyridamole Excipient Strategy and Commercial Opportunities

Last updated: September 24, 2026

Aspirin and extended-release dipyridamole is a mature antiplatelet combination with limited active patent protection but meaningful formulation barriers. The commercial opportunity is concentrated in generic substitution, differentiated modified-release capsules, adherence-oriented presentations, and lifecycle products that improve gastrointestinal tolerability or simplify dosing. The key technical challenge is maintaining immediate-release aspirin exposure while delivering dipyridamole over an extended period in a single capsule.

What drug product contains aspirin and extended-release dipyridamole?

The reference product is Aggrenox, marketed in the United States by Boehringer Ingelheim Pharmaceuticals.

Product attribute	Aggrenox specification
Active ingredients	Aspirin and dipyridamole
Strength per capsule	Aspirin 25 mg; extended-release dipyridamole 200 mg
Dosage form	Hard gelatin capsule
Dosing	One capsule twice daily
FDA application	NDA 020535
Primary use	Secondary prevention of stroke in patients with prior ischemic stroke or transient ischemic attack
Release design	Immediate-release aspirin plus extended-release dipyridamole
Reference sponsor	Boehringer Ingelheim Pharmaceuticals
Regulatory pathway for competitors	Abbreviated New Drug Application, or ANDA

The product combines two distinct pharmacokinetic profiles. Aspirin is released promptly to inhibit platelet cyclooxygenase-1. Dipyridamole is delivered over an extended period to maintain antiplatelet activity while limiting the need for more frequent dosing. The DailyMed label identifies a capsule containing an immediate-release aspirin component and modified-release dipyridamole pellets (Boehringer Ingelheim, 2023).

How does the Aggrenox formulation control drug release?

The core formulation strategy is a multiparticulate capsule. Aspirin is incorporated into an immediate-release portion, while dipyridamole is supplied through coated pellets designed for extended release.

Immediate-release aspirin component

Aspirin presents several formulation risks:

• Hydrolysis to salicylic acid in the presence of moisture.
• Sensitivity to elevated temperature and high relative humidity.
• Potential interaction with alkaline excipients.
• Reduced chemical stability if exposed to aqueous processing.
• Irritation risk in the upper gastrointestinal tract.

The commercial strategy is therefore to use a low-moisture manufacturing process, protect aspirin from alkaline microenvironments, and avoid excipient combinations that accelerate hydrolysis.

Suitable excipient classes include:

Function	Potential excipient approach
Filler	Microcrystalline cellulose, anhydrous lactose, mannitol
Binder	Povidone, low-substituted hydroxypropyl cellulose
Disintegrant	Crospovidone or croscarmellose sodium
Glidant	Colloidal silicon dioxide
Lubricant	Low-level magnesium stearate or sodium stearyl fumarate
Moisture control	Desiccant packaging, low-water excipients, alu-alu blister
Taste and handling	Capsule shell or pellet coating

Anhydrous excipients are generally preferable to hydrated materials when aspirin stability is a primary concern. Magnesium stearate can be used, but excessive levels or prolonged blending may affect dissolution and powder flow.

Extended-release dipyridamole pellets

Dipyridamole is poorly soluble and has pH-dependent dissolution behavior. Its extended-release profile typically requires a multiparticulate system rather than a simple matrix capsule.

A commercial pellet system may contain:

1. An inert starter core.
2. A dipyridamole drug layer.
3. A polymeric release-controlling coating.
4. A protective or enteric coating.
5. A capsule-filling blend containing the aspirin component.

Relevant excipient and polymer classes include:

• Sugar spheres or microcrystalline cellulose starter cores.
• Povidone or hydroxypropyl cellulose as a drug-layer binder.
• Hypromellose for film formation.
• Ethylcellulose for sustained release.
• Methacrylic acid copolymers for pH-dependent release.
• Triethyl citrate or triacetin as plasticizers.
• Talc as an anti-tacking agent.
• Colloidal silicon dioxide as a flow aid.

The formulation must balance release duration against dipyridamole’s low aqueous solubility. A coating that is too dense can produce incomplete release. A coating that is too permeable can cause dose dumping or loss of the intended extended-release profile.

What excipients are used in the reference product?

Public labeling identifies excipient classes associated with the reference capsule, including hypromellose, methacrylic acid copolymer, povidone, sucrose, talc, titanium dioxide, triacetin, corn starch and colloidal silicon dioxide. The gelatin capsule shell contains colorants and titanium dioxide in accordance with the marketed presentation (Boehringer Ingelheim, 2023).

The reference excipient architecture indicates several formulation priorities:

• Immediate release of aspirin.
• Controlled delivery of dipyridamole.
• Protection of coated pellets during capsule filling.
• Adequate flow and content uniformity.
• Moisture protection.
• Acceptable capsule appearance and swallowing characteristics.

A generic manufacturer does not need to copy the reference excipient composition. It must demonstrate pharmaceutical equivalence, bioequivalence and conformity with applicable FDA requirements. Excipients can differ if they do not alter safety, performance or bioequivalence.

What excipient strategy is most commercially attractive?

The most commercially attractive strategy is a low-risk generic composition that reproduces the reference release architecture while improving manufacturing robustness.

Strategy 1: Reference-like multiparticulate capsule

This is the lowest regulatory-risk option. The formulation uses:

• Immediate-release aspirin granules or powder.
• Dipyridamole extended-release pellets.
• Conventional capsule filling.
• Moisture-protective packaging.

The main advantage is alignment with the established pharmacokinetic profile. The principal disadvantage is manufacturing complexity. Pellet layering and coating require specialized equipment, process controls and in-process dissolution testing.

Strategy 2: Improved moisture-stable formulation

Aspirin degradation creates an opportunity for a formulation with stronger moisture control. Potential differentiators include:

• Anhydrous filler systems.
• Low-water capsule shells.
• High-barrier blister packaging.
• Separate sealing of aspirin-containing particles.
• Desiccant-containing bottles.
• Reduced aqueous exposure during coating.

This approach can reduce salicylic acid formation and extend shelf life. It may support a differentiated regulatory and commercial position if the product demonstrates better impurity control or longer stability under accelerated conditions.

Strategy 3: Simplified manufacturing through dry processing

Dry granulation or roller compaction can reduce exposure of aspirin to water. The process may lower manufacturing costs compared with aqueous granulation, but it creates technical issues involving:

• Blend segregation between aspirin and dipyridamole pellets.
• Pellet attrition.
• Capsule weight variation.
• Changes in dissolution caused by compaction forces.
• Uniform distribution of low-dose aspirin relative to the larger dipyridamole load.

A low-dose active ingredient in a high-dose combination requires tight control of blend uniformity and sampling strategy.

Strategy 4: Adherence-oriented presentation

Aggrenox is dosed twice daily. Commercial development could target adherence through:

• Calendarized blister packaging.
• Unit-dose packaging.
• Combination packs with administration reminders.
• Patient-specific packaging for post-stroke populations.
• Modified capsule size or capsule-shell design.

A once-daily formulation would be more commercially valuable but would represent a higher technical and regulatory burden. It could require a new pharmacokinetic profile, clinical bridging and potentially a 505(b)(2) strategy rather than a conventional ANDA.

What formulation patents protect aspirin and dipyridamole products?

The foundational patent estate for the aspirin and dipyridamole combination was directed to the combination and modified-release formulation rather than to new chemical entities.

Patent	Subject matter	Commercial relevance
US 5,204,116	Pharmaceutical composition combining acetylsalicylic acid and dipyridamole	Foundational combination and formulation protection
US 5,760,085	Modified-release dipyridamole dosage-form technology associated with the commercial product architecture	Extended-release formulation protection

The earliest United States patent protection for the original combination expired before the current generic market matured. Patent term adjustments, terminal disclaimers and patent-specific expiration calculations must be checked in USPTO records and the FDA Orange Book for any specific filing date and product listing.

The current opportunity is therefore less dependent on blocking composition-of-matter rights and more dependent on:

• Manufacturing know-how.
• Coating process control.
• Bioequivalence performance.
• Stability data.
• In-process release testing.
• Supply-chain economics.
• Regulatory exclusivity associated with a particular ANDA or new formulation.

What is the FDA regulatory and Orange Book status?

Aspirin and extended-release dipyridamole is a small-molecule combination product. It is not a biologic and has no biosimilar pathway.

The principal regulatory routes are:

Development route	Use case
ANDA under section 505(j)	Generic equivalent to Aggrenox
505(b)(2) NDA	New release profile, dosage form, strength, packaging or clinical positioning
Full NDA	New clinical development program or materially different product

The Orange Book typically identifies the reference listed drug and any patent or exclusivity information submitted for that product. For a mature product such as Aggrenox, the main commercial significance of the Orange Book is confirmation of reference-product status and any remaining listed patents or exclusivity codes.

FDA approval of a generic combination requires demonstration of:

• Pharmaceutical equivalence.
• Bioequivalence for aspirin and dipyridamole.
• Comparable immediate-release and extended-release behavior.
• Acceptable impurity profile.
• Manufacturing compliance.
• Appropriate labeling and capsule composition.

Because the product contains an extended-release component, a generic sponsor generally faces more demanding dissolution and pharmacokinetic comparisons than it would for an immediate-release aspirin tablet.

When did aspirin and dipyridamole lose exclusivity?

The combination lost its principal market exclusivity after expiration of the foundational patent estate and completion of applicable FDA exclusivity periods. Aggrenox entered the U.S. market in 1999, and generic competition subsequently developed through ANDA approvals.

The relevant exclusivity categories are:

Exclusivity type	Status
New chemical entity exclusivity	Not applicable to the mature combination product
Orphan exclusivity	Not applicable to the primary stroke-prevention indication
Pediatric exclusivity	No material current commercial barrier
Patent exclusivity	Foundational protection expired
Generic exclusivity	Relevant only to individual first-filer ANDA applicants
Biosimilar exclusivity	Not applicable

The absence of active composition-of-matter exclusivity shifts competition toward price, supply reliability and formulation quality.

Which companies challenge or compete with Aggrenox?

The competitive field includes generic manufacturers with experience in modified-release capsules and combination products. Publicly reported generic competition has included manufacturers such as Teva and other ANDA sponsors, although the active supplier set can change because of discontinuations, shortages and commercial withdrawals.

The main competitive products are:

• Generic aspirin and extended-release dipyridamole capsules.
• Aspirin monotherapy.
• Clopidogrel.
• Aspirin plus clopidogrel in selected clinical settings.
• Other antiplatelet regimens determined by stroke subtype and patient risk.

Generic competition is strongest where payers treat the generic combination as therapeutically interchangeable with Aggrenox. Clinical substitution is constrained by prescribing practice, tolerability and the need to maintain the twice-daily combination regimen.

What generic entry risks exist?

Generic entry risks are primarily technical and commercial rather than patent-related.

Technical risks

• Failure to match dipyridamole exposure.
• Premature release from coated pellets.
• Incomplete release at later time points.
• Aspirin degradation during manufacture or storage.
• Content-uniformity failures.
• Capsule filling variability.
• Pellet fracture during blending.
• Difference in food effect.
• Unacceptable levels of salicylic acid or related impurities.

Commercial risks

• Low reimbursement margins.
• Price erosion after multiple ANDA approvals.
• Dependence on specialized coating capacity.
• Limited market growth in a mature stroke-prevention indication.
• Competition from low-cost clopidogrel.
• Payer preference for single-agent antiplatelet therapy.
• Product withdrawal risk if manufacturing economics deteriorate.

A sponsor with no existing multiparticulate manufacturing platform may face higher capital expenditure and longer scale-up time than a company already producing delayed-release or extended-release pellets.

How strong is the patent estate?

The legacy patent estate is weak as a barrier to conventional generic entry because the principal combination and release patents are expired or no longer provide meaningful market exclusion.

The remaining defensibility is likely to come from:

1. Process patents covering pellet coating or capsule assembly.
2. New packaging patents directed to moisture control.
3. Improved formulations with lower impurity formation.
4. Once-daily or abuse-resistant release profiles.
5. Method-of-use claims for narrowly defined patient groups.
6. Proprietary manufacturing controls and analytical methods.

Method-of-use patents would face practical limitations because the principal indication is established and generic labels are often aligned closely with the reference product. A new indication, dosing schedule or patient-selection approach would require clinical evidence and would carry greater regulatory and litigation cost.

What licensing and partnership opportunities exist?

The strongest licensing opportunities are associated with enabling technologies rather than with the old active ingredients.

Potential targets include:

• Multiparticulate coating platforms.
• Low-moisture aspirin processing.
• High-barrier capsule and blister systems.
• Continuous pellet manufacturing.
• Taste-masking and swallowability technologies.
• Unit-dose adherence packaging.
• Contract manufacturing capacity for modified-release capsules.
• Analytical platforms for multiphasic dissolution testing.

An originator-style licensing transaction for the basic aspirin-dipyridamole combination is less likely to generate substantial value because the active ingredients are generic and the principal combination patents have expired. Value is more likely in a regional supply agreement, manufacturing license or 505(b)(2) formulation partnership.

What revenue exposure does the product represent?

Aggrenox was historically a commercially important stroke-prevention product, but the market has matured and generic substitution has reduced branded revenue potential. Revenue exposure now depends on three variables:

Variable	Commercial effect
Generic count	More suppliers accelerate price erosion
Supply reliability	Shortages can temporarily restore branded or premium generic demand
Clinical preference	Continued use of dual-mechanism therapy supports volume

For a generic entrant, the product is more attractive as part of a broader modified-release portfolio than as a standalone launch. Manufacturing synergies with extended-release pellets, enteric capsules and delayed-release products can materially improve margins.

How does aspirin and dipyridamole compare with clopidogrel?

Attribute	Aspirin/extended-release dipyridamole	Clopidogrel
Dose frequency	Twice daily	Usually once daily
Dosage complexity	Multiparticulate combination capsule	Conventional tablet
Manufacturing complexity	High	Lower
Generic competition	Established	Extensive
Adherence burden	Higher	Lower
Formulation barrier	Extended-release dipyridamole and aspirin stability	Primarily solid-dose tablet manufacturing
Commercial differentiation	Packaging, release profile and tolerability	Price, supply and tablet presentation

Clopidogrel is generally easier and cheaper to manufacture. Aspirin/dipyridamole can still support a niche commercial position where clinicians prefer the combination or where a supplier can offer reliable access and adherence-focused packaging.

What are the highest-value development opportunities?

The most attractive opportunities rank as follows:

1. A bioequivalent generic using a robust, reference-like pellet system.
2. A high-stability product with improved aspirin impurity control.
3. A calendarized or unit-dose package designed for post-stroke adherence.
4. A 505(b)(2) once-daily formulation with validated exposure.
5. A regional contract-manufacturing platform for multiparticulate antiplatelet products.
6. A differentiated product using a smaller capsule or improved swallowability.

The first two options have the clearest regulatory path. The once-daily product has the highest potential differentiation but also the highest clinical, regulatory and development cost.

Key Takeaways

• The commercial reference product is Aggrenox, containing 25 mg aspirin and 200 mg extended-release dipyridamole per capsule.
• Its central formulation challenge is combining immediate-release aspirin with extended-release dipyridamole in one dosage form.
• Aspirin requires moisture and impurity control; dipyridamole requires multiparticulate release engineering.
• The foundational patent estate is expired or commercially weak as a barrier to conventional generic entry.
• No biosimilar pathway applies because both active ingredients are small molecules.
• The strongest opportunities are generic entry, moisture-stable formulations, specialized packaging and adherence-oriented presentations.
• Manufacturing capability in pellet layering, polymer coating and multiphasic dissolution testing is a central competitive advantage.
• A once-daily product could be differentiated but would likely require a 505(b)(2) development strategy.
• Licensing value is concentrated in formulation, coating, packaging and manufacturing technologies rather than in the active ingredients.

FAQs

Is aspirin and dipyridamole an extended-release product?

Yes. Aspirin is released immediately, while dipyridamole is delivered through an extended-release multiparticulate system.

Can aspirin and dipyridamole be formulated as a tablet?

Technically, yes, but a conventional tablet must reproduce the separate immediate-release and extended-release profiles. A multiparticulate capsule is generally more practical for matching the reference product.

Which excipient is most important for dipyridamole release?

The release-controlling polymer system is most important. Hypromellose, ethylcellulose and methacrylic acid copolymers can materially affect release rate, pH response and bioequivalence.

What packaging best protects aspirin and dipyridamole capsules?

High-barrier blister packaging, particularly aluminum-based blister systems, provides strong protection against moisture and oxygen. Desiccant bottles can also be used if container-closure performance is validated.

Is a new aspirin and dipyridamole formulation eligible for 505(b)(2) approval?

A materially different release profile, dosage form, strength or administration schedule may support a 505(b)(2) NDA, subject to FDA requirements for bridging, pharmacokinetic evaluation and any needed clinical data.

References

1. Boehringer Ingelheim Pharmaceuticals, Inc. (2023). Aggrenox (aspirin and extended-release dipyridamole) capsules prescribing information. U.S. Food and Drug Administration DailyMed.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Center for Drug Evaluation and Research.

3. U.S. Food and Drug Administration. (2024). Orange Book: Approved drug products with therapeutic equivalence evaluations. U.S. Department of Health and Human Services.

4. U.S. Patent No. 5,204,116. (1993). Pharmaceutical composition containing acetylsalicylic acid and dipyridamole. U.S. Patent and Trademark Office.

5. U.S. Patent No. 5,760,085. (1998). Modified-release dipyridamole dosage-form technology. U.S. Patent and Trademark Office.