ASPIRIN; PROPOXYPHENE NAPSYLATE - Generic Drug Details

What are the generic drug sources for aspirin; propoxyphene napsylate and what is the scope of freedom to operate?

Aspirin; propoxyphene napsylate is the generic ingredient in one branded drug marketed by Aaipharma Llc and is included in two NDAs. Additional information is available in the individual branded drug profile pages.

Summary for ASPIRIN; PROPOXYPHENE NAPSYLATE

US Patents:	0
Tradenames:	1
Applicants:	1
NDAs:	2
DailyMed Link:	ASPIRIN; PROPOXYPHENE NAPSYLATE at DailyMed

US Patents and Regulatory Information for ASPIRIN; PROPOXYPHENE NAPSYLATE

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Aaipharma Llc	DARVON-N W/ ASA	aspirin; propoxyphene napsylate	TABLET;ORAL	016863-001	Approved Prior to Jan 1, 1982		DISCN	No	No
Aaipharma Llc	DARVON-N W/ ASA	aspirin; propoxyphene napsylate	CAPSULE;ORAL	016829-001	Approved Prior to Jan 1, 1982		DISCN	No	No

Aspirin and Propoxyphene Napsylate Market Dynamics and Financial Trajectory

Last updated: September 7, 2026

Aspirin is a mature, low-cost global medicine with durable demand in analgesia, antipyresis, cardiovascular secondary prevention, and combination products. Its market is fragmented among branded, private-label, hospital, and generic suppliers. Revenue growth is driven mainly by volume, pricing, formulation changes, and channel mix rather than patent exclusivity.

Propoxyphene napsylate has no meaningful U.S. commercial trajectory. The FDA requested withdrawal of propoxyphene products in 2010 after concluding that the drug created a risk of serious, potentially fatal cardiac toxicity. Xanodyne Pharmaceuticals withdrew Darvon and Darvocet from the U.S. market, and generic manufacturers discontinued equivalent products. The asset has no viable U.S. branded or generic growth thesis [1].

What are the current market positions of aspirin and propoxyphene napsylate?

Attribute	Aspirin	Propoxyphene napsylate
Primary use	Pain, fever, inflammation, cardiovascular secondary prevention	Opioid analgesia, historically for mild-to-moderate pain
U.S. status	Widely marketed over the counter and by prescription in selected products	Withdrawn from the U.S. market
Regulatory maturity	Long-established active pharmaceutical ingredient	Discontinued U.S. product
Patent dependence	Minimal for core aspirin; limited to newer formulations and combinations	No commercially relevant U.S. patent platform
Competitive structure	Highly fragmented; Bayer, private labels, generics, combination-product manufacturers	No active U.S. branded market
Demand base	Large, recurring, low-price demand	Effectively zero in the United States
Financial outlook	Stable volume with modest nominal growth	Negative to nil commercial outlook
Principal risks	Generic price competition, substitution, safety warnings, retailer margin pressure	Regulatory withdrawal, liability, controlled-substance restrictions, loss of market access

Aspirin remains a global consumer-health product because it is inexpensive, familiar, widely distributed, and available in multiple strengths and dosage forms. Propoxyphene napsylate is a discontinued opioid product whose historical revenue base disappeared after regulatory action.

How large is the aspirin market and what drives revenue?

Aspirin revenue is difficult to isolate because manufacturers report it within broader consumer-health portfolios. Bayer, the best-known branded aspirin supplier, generally reports consumer-health categories rather than a standalone global aspirin revenue line. Public filings therefore do not establish a precise, audited worldwide aspirin figure.

The commercial structure has five main components:

1. Branded OTC aspirin, including Bayer Aspirin and regional equivalents.
2. Store-brand and private-label tablets.
3. Hospital and institutional supply.
4. Low-dose aspirin for cardiovascular secondary prevention.
5. Combination products for pain, cold, migraine, and gastrointestinal indications.

The largest commercial constraint is price. Standard aspirin tablets are widely available as low-cost generics, so market share does not translate directly into high margins. Branded products can preserve pricing through consumer recognition, packaging, dosing guidance, enteric-coated formats, and retail placement. The underlying active ingredient remains inexpensive and readily available from multiple chemical manufacturers.

Which aspirin products have the strongest commercial positioning?

The most defensible commercial positions are not based on the aspirin molecule itself. They are based on brand, formulation, distribution, and combination-product execution.

Product segment	Commercial characteristics	Margin profile
Standard immediate-release tablets	Commodity product with intense price competition	Low
Chewable aspirin	Useful for emergency cardiovascular administration and consumer convenience	Low to moderate
Enteric-coated aspirin	Differentiated by tolerability and dosing presentation	Moderate
Low-dose aspirin	Large recurring demand in cardiovascular prevention, but medical guidance limits growth	Low to moderate
Effervescent products	Stronger regional differentiation and convenience	Moderate
Aspirin combinations	Higher average selling price and more formulation differentiation	Moderate to high
Hospital supply	Volume-oriented procurement and tender pricing	Low

Aspirin’s strongest recurring demand is the low-dose segment. That market is constrained by clinical recommendations. The FDA states that daily aspirin for primary prevention should not be initiated routinely without an individualized assessment of cardiovascular and bleeding risk. Secondary prevention remains a more durable use case for appropriate patients [2].

What is the financial trajectory for aspirin?

Aspirin’s financial trajectory is stable but mature. The expected pattern is low single-digit nominal growth in favorable markets, offset by periodic volume erosion from generic substitution, retailer negotiations, and declining use in some primary-prevention populations.

Revenue drivers

Aspirin revenue can increase through:

• Retail price increases, although affordability limits pricing power.
• Growth in private-label and pharmacy-channel distribution.
• Expansion of enteric-coated, chewable, effervescent, and combination products.
• Emerging-market population growth and increased access to OTC medicines.
• Hospital and institutional procurement.
• Brand advertising and shelf placement.
• Premium packaging and convenience formats.

Revenue pressures

The principal pressures are:

• Very low barriers to generic manufacturing.
• Retailer and pharmacy purchasing power.
• Substitution by acetaminophen, ibuprofen, naproxen, and combination products.
• Safety concerns involving gastrointestinal bleeding and hemorrhagic stroke.
• Reduced use for primary cardiovascular prevention.
• Limited patent protection for the core molecule.
• Commodity exposure in active pharmaceutical ingredient and packaging costs.

Aspirin has a favorable volume profile but a constrained pricing profile. A manufacturer with a broad consumer-health platform can use aspirin for distribution scale and customer retention, but a standalone aspirin business is unlikely to generate pharmaceutical-style margins.

When does aspirin lose exclusivity?

Aspirin has no relevant modern U.S. composition-of-matter exclusivity. Acetylsalicylic acid was introduced commercially more than a century ago, and the core compound is in the public domain.

No current Orange Book patent protects aspirin as a basic active ingredient. Product-specific patents may apply to a formulation, delivery system, combination, manufacturing process, or branded package, but these rights do not prevent competitors from selling ordinary aspirin tablets.

Exclusivity category	Aspirin position
Core compound patent	Expired
FDA new chemical entity exclusivity	None
Pediatric exclusivity	Not relevant to the core product
Orphan exclusivity	Not applicable to ordinary aspirin
Core Orange Book protection	No meaningful protection
Formulation protection	Possible for selected products, generally narrow
Brand protection	Trademark and trade dress, not molecular exclusivity

Trademark rights can protect names such as Bayer Aspirin, but they do not prevent sales of aspirin under generic or private-label names.

What patents protect aspirin formulations?

Aspirin formulation patents can cover enteric coatings, delayed release, effervescent systems, combination therapies, dosage regimens, and manufacturing processes. The commercial value of these patents depends on claim scope, remaining term, regulatory listing, and whether consumers or prescribers view the formulation as substitutable.

A formulation patent generally does not block:

• Conventional immediate-release aspirin.
• Unrelated aspirin strengths.
• Competing enteric-coated products outside the patent claims.
• Private-label products using a different manufacturing process.
• Non-aspirin analgesics.

The principal intellectual-property assets in the aspirin category are therefore trademarks, packaging, channel relationships, manufacturing know-how, and regulatory compliance systems. Formulation patents can support a premium product but rarely create a durable monopoly over the category.

What is the FDA and Orange Book status of propoxyphene napsylate?

The FDA requested removal of all propoxyphene products from the U.S. market in November 2010. The agency cited new data showing dose-dependent changes in cardiac electrical activity, including prolongation of the QT interval, which could increase the risk of serious arrhythmias [1].

The action affected products containing propoxyphene, including propoxyphene napsylate and propoxyphene hydrochloride combinations. Darvon and Darvocet were withdrawn, and generic equivalents were discontinued.

Regulatory event	Date	Business effect
FDA announced new cardiac safety data	July 2009	Labeling and safety scrutiny increased
FDA requested market withdrawal	November 2010	U.S. commercial market terminated
Manufacturers discontinued products	2010-2011	Brand and generic revenue ended
FDA safety communications continued	After withdrawal	Re-entry risk remained commercially prohibitive

Propoxyphene napsylate has no active U.S. commercial opportunity comparable to an Orange Book-listed marketed product. The relevant issue is not patent expiry. It is loss of regulatory authorization and market access.

Which companies challenged or discontinued propoxyphene products?

Propoxyphene products were not displaced by ordinary Paragraph IV litigation. The commercial outcome resulted from regulatory withdrawal and manufacturer discontinuation.

Xanodyne Pharmaceuticals was the principal company associated with the U.S. branded products Darvon and Darvocet. Generic manufacturers also removed their products following the FDA action. The withdrawal eliminated the need for a conventional generic-entry contest because the reference products and equivalents were no longer lawfully marketed in the United States.

Were there propoxyphene patent settlements?

No commercially relevant U.S. patent-settlement framework drove the market exit. The decisive event was the FDA withdrawal request, not an agreement resolving a Paragraph IV challenge.

What is the international status of propoxyphene napsylate?

Propoxyphene status differs by jurisdiction, but the overall global direction has been withdrawal or severe restriction. The European Medicines Agency recommended withdrawal of marketing authorizations for propoxyphene-containing medicines in the European Union because the risks outweighed the benefits [3].

The United Kingdom withdrew co-proxamol, a propoxyphene and paracetamol combination, through a phased process beginning in 2005. Other jurisdictions also restricted or removed propoxyphene products.

Geographic market	General status
United States	Withdrawn
European Union	Marketing authorizations withdrawn
United Kingdom	Co-proxamol phased out
Other markets	Restrictions or withdrawal varied by country
Global commercial outlook	No credible growth platform

A country-specific product may remain subject to local historical registration rules, but international regulatory policy has materially reduced the asset’s value.

What generic entry risks exist for aspirin?

Generic-entry risk is structurally high because ordinary aspirin is already generic. The relevant competitive risk is not a future launch after patent expiry. It is continuous price erosion and substitution.

For branded aspirin, the main threats are:

• Store-brand replication.
• Pharmacy benefit substitution.
• Retailer-owned brands.
• Hospital tender competition.
• Contract manufacturing by low-cost suppliers.
• Consumer switching between brands based on price.
• Combination-product substitution.

A manufacturer can defend share through quality controls, supply reliability, brand recognition, child-resistant or senior-friendly packaging, and differentiated dosage forms. Those defenses support market share but do not create pharmaceutical exclusivity.

What manufacturing and intellectual-property barriers affect the two drugs?

Aspirin

Manufacturing barriers are moderate at the operational level and low at the molecular level. Competitors need compliant facilities, validated processes, quality systems, packaging capacity, and regulatory registrations. The synthesis of acetylsalicylic acid is well established, and the active ingredient is available from multiple suppliers.

Potential barriers include:

• Good Manufacturing Practice compliance.
• Control of hydrolysis and degradation.
• Stability and moisture management.
• Enteric-coating performance.
• Dissolution testing.
• Supply-chain reliability.
• Product liability and pharmacovigilance.
• Retail distribution access.

Propoxyphene napsylate

Manufacturing capability is not the principal barrier. A technically feasible product would face regulatory, clinical, liability, controlled-substance, and market-access barriers. The cardiac safety record makes a U.S. relaunch commercially implausible without a substantial regulatory reversal and a compelling new risk-benefit profile.

How does aspirin compare with propoxyphene napsylate financially?

Financial factor	Aspirin	Propoxyphene napsylate
Current U.S. sales	Active and recurring	None as an approved marketed product
Pricing power	Low	Not applicable
Gross-margin potential	Low for commodity tablets; higher for differentiated formats	Negative risk profile for any relaunch
Patent value	Limited, formulation-specific	No meaningful current U.S. value
Regulatory risk	Routine OTC and product-safety compliance	Fundamental market-access barrier
Litigation exposure	Product liability and labeling risk	Historical opioid and cardiac-safety exposure
Growth strategy	Distribution, formulations, combinations, emerging markets	No viable conventional growth strategy
Investor relevance	Stable mature consumer-health cash flow	Discontinued asset with residual liability considerations

What litigation and liability issues affect the products?

Aspirin faces ordinary OTC product-liability exposure involving gastrointestinal bleeding, allergic reactions, dosing errors, pediatric use, and labeling. Its long history and widespread use reduce market uncertainty but do not eliminate litigation risk.

Propoxyphene faces a substantially different risk profile. The FDA’s withdrawal was tied to cardiac toxicity, while opioid-related litigation and controlled-substance compliance created further commercial liabilities. Any rights holder evaluating historical propoxyphene assets would focus more on litigation reserves, product records, insurance, and regulatory obligations than on patent monetization.

Key Takeaways

• Aspirin is a mature, global, low-margin medicine with durable demand and limited patent protection.
• Its financial performance depends on volume, retail distribution, branding, formulation, and combination products.
• The aspirin molecule is long off patent; formulation patents are narrow and product-specific.
• Low-dose aspirin remains commercially important, but primary-prevention use is constrained by FDA safety guidance.
• Propoxyphene napsylate has no meaningful U.S. market after the FDA’s 2010 withdrawal.
• Propoxyphene’s central commercial issue is regulatory and liability risk, not patent expiry.
• There is no credible U.S. generic-launch opportunity for propoxyphene napsylate under its withdrawn regulatory status.
• Aspirin offers stable but modest consumer-health economics; propoxyphene offers no comparable forward revenue base.

FAQs About Aspirin and Propoxyphene Napsylate

Is aspirin still profitable for pharmaceutical companies?

Yes, but profitability varies sharply by product. Commodity aspirin tablets have low margins. Branded, enteric-coated, chewable, effervescent, and combination products can generate better economics through formulation and brand premiums.

Does Bayer have an exclusive patent on aspirin?

No. Bayer does not have an exclusive patent on the aspirin molecule. Its commercial protection comes primarily from trademarks, brand recognition, distribution, packaging, and selected product-specific rights.

Can a company launch a generic version of propoxyphene napsylate in the United States?

Not as a routine generic opportunity. The FDA requested withdrawal of propoxyphene products because of cardiac safety risks. A manufacturer would face a fundamental regulatory barrier rather than a standard patent-expiry launch.

Is propoxyphene napsylate the same as Darvon?

Darvon was a brand associated with propoxyphene products. Propoxyphene napsylate is the napsylate salt form used in certain products, while propoxyphene hydrochloride was used in others. Both forms were affected by the U.S. withdrawal of propoxyphene medicines.

What is the investment case for aspirin compared with discontinued opioids?

Aspirin supports recurring, diversified consumer-health demand but has limited pricing power. Discontinued opioids such as propoxyphene napsylate lack current revenue and carry regulatory, product-liability, and remediation risks. The two assets have fundamentally different risk-return profiles.

References

1. U.S. Food and Drug Administration. (2010, November 19). FDA recommends against the continued use of propoxyphene. https://www.fda.gov
2. U.S. Food and Drug Administration. (2014, May 2). FDA recommends against use of aspirin for primary prevention of first heart attack or stroke. https://www.fda.gov
3. European Medicines Agency. (2009, June 25). European Medicines Agency recommends withdrawal of marketing authorisations for dextropropoxyphene-containing medicines. https://www.ema.europa.eu
4. Bayer AG. (2024). Annual report 2023. https://www.bayer.com
5. U.S. Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/屑