When will the patents on PROPOXYPHENE HYDROCHLORIDE W/ ASPIRIN AND CAFFEINE expire, and when will PROPOXYPHENE HYDROCHLORIDE W/ ASPIRIN AND CAFFEINE go generic?

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Watson Labs	PROPOXYPHENE HYDROCHLORIDE W/ ASPIRIN AND CAFFEINE	aspirin; caffeine; propoxyphene hydrochloride	CAPSULE;ORAL	085732-002	Sep 3, 1984		DISCN	No	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: August 9, 2026

Propoxyphene hydrochloride with aspirin and caffeine is a discontinued legacy analgesic combination with no viable U.S. commercial market. Its trajectory was shaped by declining clinical use, opioid safety concerns, regulatory withdrawal, and the absence of a defensible modern patent estate. The FDA required withdrawal of all propoxyphene-containing products from the U.S. market in 2010 after evidence linked therapeutic dosing to potentially serious or fatal cardiac rhythm abnormalities (FDA, 2010).

The product has no meaningful current revenue base, no active U.S. exclusivity, no biosimilar exposure, and no credible generic-launch opportunity in the United States. Any remaining commercial activity would be limited to historical, non-U.S., archival, or unauthorized channels.

What is propoxyphene hydrochloride with aspirin and caffeine?

Propoxyphene hydrochloride with aspirin and caffeine was an opioid-containing combination analgesic intended for mild to moderate pain. The formulation combined:

Propoxyphene hydrochloride, an opioid analgesic
Aspirin, a nonsteroidal analgesic and antiplatelet agent
Caffeine, used in analgesic combinations to enhance perceived pain relief

The product belonged to the same commercial class as propoxyphene combinations marketed under the Darvon and Darvocet families. Product-specific strengths and branding varied by manufacturer and jurisdiction. The best-known U.S. combination products generally paired propoxyphene with aspirin and caffeine or with acetaminophen.

Propoxyphene was originally developed and commercialized by Eli Lilly and Company. The active ingredient was later supplied through multiple manufacturers and generic distributors.

When did propoxyphene lose exclusivity?

Propoxyphene lost meaningful market exclusivity decades before its regulatory withdrawal. The relevant composition, formulation, and product patents were associated with an older small-molecule drug launched in the 1950s. Any original U.S. patent protection would have expired long before the 2010 withdrawal.

Commercial factor	Status
Original drug class	Legacy opioid analgesic
U.S. market launch	1950s
Patent maturity	Original patent estate expired decades ago
Generic competition	Present before withdrawal
FDA market status	Withdrawn from U.S. market in 2010
Current U.S. exclusivity	None
Current U.S. Orange Book protection	No active commercial protection
Biosimilar exposure	Not applicable
Commercial status	Discontinued

The product’s economic life therefore followed a conventional sequence: originator launch, generic erosion, prolonged mature-product sales, safety-driven regulatory intervention, and market exit.

What was the FDA regulatory status of propoxyphene combinations?

The FDA concluded that the cardiac risks of propoxyphene outweighed its limited analgesic benefit. On November 19, 2010, the agency announced that all propoxyphene products would be withdrawn from the U.S. market at the request of the manufacturer (FDA, 2010).

The action followed electrocardiographic studies showing dose-dependent prolongation of the QT interval. The concern was clinically important because dangerous arrhythmias could occur without clear warning symptoms. FDA had previously required stronger warnings and a boxed warning, but concluded that those measures did not adequately reduce risk.

U.S. regulatory timeline

Date	Regulatory event
1950s	Propoxyphene commercialized in the United States
1970s-2000s	Generic and combination products remain available
2009	European regulators recommend withdrawal of propoxyphene products
2010	FDA requests withdrawal of all U.S. propoxyphene products
November 2010	U.S. commercial distribution ends
Post-2010	No routine FDA-approved U.S. market for propoxyphene combinations

The European Medicines Agency reached a similar conclusion in 2009, recommending withdrawal because the safety risks exceeded the limited benefits of the drug (European Medicines Agency, 2009).

What was the Orange Book status of propoxyphene hydrochloride with aspirin and caffeine?

There is no current Orange Book commercial position supporting propoxyphene hydrochloride with aspirin and caffeine in the United States. The Orange Book may retain historical records for discontinued products or applications, but historical listing does not establish current marketability.

No active U.S. reference-product exclusivity protects the combination. Any historical New Drug Application or Abbreviated New Drug Application record has no practical commercial value after withdrawal of the active ingredient from the U.S. market.

The principal barriers are regulatory, not patent-based:

Propoxyphene products are no longer authorized for ordinary U.S. marketing.
A new sponsor would need to address the FDA’s prior benefit-risk determination.
Existing generic bioequivalence pathways do not overcome the withdrawal decision.
Reintroduction would require substantial clinical, safety, and regulatory justification.

How many patents cover propoxyphene hydrochloride with aspirin and caffeine?

No active patent estate is known to provide commercially relevant protection for the discontinued U.S. product.

Historical protection likely covered the active compound, salt forms, combinations, dosage forms, and manufacturing processes. Those rights would have expired under the applicable patent terms. Product-specific formulation patents, if any existed, would not restore market exclusivity after the underlying drug was withdrawn.

Patent category	Current commercial relevance
Propoxyphene compound patents	Expired
Hydrochloride salt claims	Expired or commercially irrelevant
Aspirin-caffeine combination claims	Expired or unenforceable against ordinary market entry
Tablet formulation claims	Expired or commercially irrelevant
Manufacturing-process patents	Expired or avoidable
Method-of-use patents	No current U.S. market value
Patent-term extension	No meaningful current protection
Patent litigation risk	Minimal compared with regulatory risk

The product is therefore an example of a legacy medicine whose patent risks ended well before its commercial life ended.

What formulation patents protected the product?

Historical formulation protection could have addressed tablet composition, excipient ratios, dissolution characteristics, stability, and combination-dose uniformity. Those claims were commercially relevant during the originator and early generic periods.

They do not create a current barrier. Aspirin and caffeine are long-established ingredients, and propoxyphene hydrochloride is an old active pharmaceutical ingredient. A modern formulation patent would need to claim a genuinely novel product, delivery system, or therapeutic use. It could not revive the withdrawn product without resolving the FDA’s safety determination.

The most important technical constraint is pharmacological rather than manufacturing-related. Propoxyphene’s metabolite, norpropoxyphene, has been associated with cardiac electrophysiology concerns. Changing excipients or tablet hardness would not eliminate the fundamental risk profile identified by regulators.

Were there Paragraph IV challenges?

Paragraph IV litigation was not the defining market event for this product. Propoxyphene was already subject to extensive generic competition before withdrawal, and the drug’s commercial failure resulted from safety action rather than a patent-based generic challenge.

A Paragraph IV certification is relevant only when an ANDA applicant seeks approval against listed patents. With the historical patent estate expired and the reference products withdrawn, there is no current commercial pathway in which a conventional Paragraph IV challenge would create a meaningful launch opportunity.

The likely sequence for a hypothetical U.S. entrant would be regulatory review of a new or reinstated product, not conventional patent litigation against an active branded reference product.

What litigation and settlement agreements affected propoxyphene?

The central legal and regulatory exposure involved product-liability claims, state and federal regulatory actions, and withdrawal-related commercial consequences. The product’s main risk was not a continuing patent dispute between an innovator and generic manufacturers.

Propoxyphene was associated with warnings concerning overdose, respiratory depression, dependence, and cardiac toxicity. Litigation exposure increased as evidence accumulated that serious events could occur even at prescribed doses. The withdrawal reduced future sales but did not eliminate historical liability associated with prior use.

There is no widely reported current settlement structure that creates a continuing commercial constraint comparable to a typical branded-drug patent settlement. Any historical settlements would have limited relevance to present-day market entry because the product is no longer an active U.S. market.

Which companies challenged or replaced propoxyphene products?

The competitive landscape changed in two stages.

Generic competition before withdrawal

Before 2010, multiple manufacturers sold propoxyphene products or authorized generic equivalents. Competition reduced pricing power and shifted volume away from the original brand. The market included branded products, authorized generics, and pharmacy-distributed generic combinations.

Therapeutic substitution after withdrawal

After withdrawal, prescribers and payers shifted patients toward alternatives such as:

Tramadol
Codeine combinations
Hydrocodone combinations, before later opioid restrictions
Nonsteroidal anti-inflammatory drugs
Acetaminophen-based analgesics
Other short-acting opioid products

The replacement market was fragmented. No single product captured the entire propoxyphene revenue pool because treatment choice depended on pain severity, patient age, renal and hepatic status, opioid risk, and payer formulary design.

What was the financial trajectory of propoxyphene?

Propoxyphene followed the financial pattern of an aging, low-cost prescription analgesic.

Revenue trajectory

Period	Financial condition
Initial commercialization	Originator-led pricing and brand demand
Mature brand period	Broad physician familiarity and stable prescription volume
Generic period	Price erosion and declining branded share
Pre-withdrawal period	Reduced growth, safety concerns, and substitution pressure
2010 withdrawal	Abrupt loss of U.S. product revenue
Post-withdrawal	No legitimate recurring U.S. revenue base

Public filings generally reported propoxyphene within broader pharmaceutical portfolios rather than as a separately disclosed product line. A reliable standalone revenue series for the aspirin-caffeine combination is therefore not established in standard public-company reporting.

The largest financial impact was not lost future growth. It was the termination of residual cash flow from a mature product, combined with potential legal, recall, inventory, and regulatory costs. Because the product had already faced generic erosion, its marginal profitability likely depended on manufacturing scale, low acquisition cost, and residual brand recognition rather than patent pricing.

What generic entry risks exist for propoxyphene?

A conventional generic launch in the United States faces a regulatory prohibition rather than a patent obstacle.

U.S. generic-launch scenarios

Scenario	Commercial probability	Main barrier
Ordinary ANDA launch against withdrawn product	Very low	No active U.S. market authorization
New NDA or 505(b)(2) product	Very low	Benefit-risk and cardiac safety concerns
Reformulated propoxyphene product	Very low	Reformulation does not resolve active-ingredient risk
Non-U.S. launch	Jurisdiction-specific	Local withdrawal and controlled-substance rules
Unauthorized supply	Illegal	Regulatory and criminal enforcement exposure

In practical terms, a generic manufacturer would gain little from defeating old patents. The product’s commercial opportunity disappeared because regulators determined that the active ingredient should no longer be marketed.

Is there biosimilar risk for propoxyphene hydrochloride?

No. Propoxyphene hydrochloride is a conventional small-molecule drug, not a biologic. Biosimilar legislation and biologic reference-product exclusivity do not apply.

The relevant competitive risks are generic substitution, therapeutic substitution, and regulatory replacement by safer analgesics. Those risks were already present before the final withdrawal.

What geographic markets remain for propoxyphene?

The United States and European Union removed propoxyphene products from ordinary commercial use. Other jurisdictions may have had different timelines or residual listings, but the global regulatory direction was restrictive.

Geographic market value is limited by:

National controlled-substance rules
Product-registration status
Pharmacovigilance requirements
Import and export controls
Local withdrawal decisions
Physician reluctance to prescribe an obsolete opioid

A country-specific historical listing does not establish an investable market. The product lacks the regulatory momentum, clinical positioning, and commercial support required for a modern international launch.

How strong is the patent estate for propoxyphene compared with active analgesics?

Attribute	Propoxyphene combination	Modern branded analgesic
Composition patent life	Expired	May remain active
Formulation differentiation	Limited	Often central to lifecycle strategy
Method-of-use protection	Historical or limited	Potentially important
Regulatory status	Withdrawn in U.S.	Active for marketed products
Generic competition	Historical and extensive	Depends on patent status
Biosimilar risk	None	Applies only to biologics
Manufacturing barrier	Low to moderate	Can be high for complex products
Commercial pricing power	None today	Depends on exclusivity
Litigation value	Low	Potentially high

Propoxyphene has a weak patent estate by current commercial standards. Its value was based on historical brand recognition and established prescribing patterns, not on continuing intellectual-property protection.

Key Takeaways

Propoxyphene hydrochloride with aspirin and caffeine is a discontinued legacy opioid combination.
The FDA withdrew all U.S. propoxyphene products in 2010 after cardiac safety concerns.
Original compound, formulation, and combination patents expired decades ago.
No active U.S. Orange Book exclusivity supports current commercial sales.
Paragraph IV litigation is not the principal market-entry issue.
Biosimilar risk does not apply because propoxyphene is a small molecule.
The product’s financial trajectory ended with generic erosion followed by regulatory withdrawal.
Any current U.S. launch would face a benefit-risk and regulatory barrier, not a patent barrier.
Therapeutic substitutes, including tramadol, codeine products, NSAIDs, and acetaminophen-based analgesics, absorbed demand after withdrawal.
Product-level historical revenue is generally not separately disclosed in public filings.

FAQs

Why was propoxyphene with aspirin and caffeine discontinued?

It was discontinued because propoxyphene was associated with potentially fatal cardiac rhythm abnormalities, including QT prolongation, even at therapeutic doses. FDA determined that the risks outweighed the drug’s limited pain-relief benefit (FDA, 2010).

Can a company still sell propoxyphene hydrochloride in the United States?

No ordinary commercial U.S. market remains for FDA-approved propoxyphene products. The active ingredient was withdrawn from the U.S. market in 2010.

Did propoxyphene have a patent-protected combination with aspirin and caffeine?

Historical composition and formulation rights may have covered specific combinations, but those rights expired. They do not create current commercial exclusivity.

What drug replaced propoxyphene after withdrawal?

Replacement varied by patient and indication. Physicians used tramadol, codeine combinations, NSAIDs, acetaminophen products, and other analgesics depending on clinical circumstances and opioid-risk considerations.

Is propoxyphene still relevant to pharmaceutical investors?

Only as a historical case involving late-stage product erosion, opioid safety regulation, product-liability exposure, and the limits of patent value after a benefit-risk determination changes. It has no meaningful current U.S. revenue opportunity.

References

European Medicines Agency. (2009). European Medicines Agency recommends withdrawal of dextropropoxyphene-containing medicines. https://www.ema.europa.eu/
U.S. Food and Drug Administration. (2010, November 19). FDA drug safety communication: FDA recommends against the continued use of propoxyphene. https://www.fda.gov/
U.S. Food and Drug Administration. (2010). Questions and answers: FDA recommends withdrawal of propoxyphene products. https://www.fda.gov/
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

US Patents:	0
Applicants:	1
NDAs:	1
DailyMed Link:	PROPOXYPHENE HYDROCHLORIDE W/ ASPIRIN AND CAFFEINE at DailyMed

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