DARVON COMPOUND Drug Patent Profile

Which patents cover Darvon Compound, and what generic alternatives are available?

Darvon Compound is a drug marketed by Xanodyne Pharm and is included in one NDA.

The generic ingredient in DARVON COMPOUND is aspirin; caffeine; propoxyphene hydrochloride. There is one drug master file entry for this compound. Additional details are available on the aspirin; caffeine; propoxyphene hydrochloride profile page.

Summary for DARVON COMPOUND

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	126
DailyMed Link:	DARVON COMPOUND at DailyMed

US Patents and Regulatory Information for DARVON COMPOUND

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Xanodyne Pharm	DARVON COMPOUND	aspirin; caffeine; propoxyphene hydrochloride	CAPSULE;ORAL	010996-006	Mar 8, 1983		DISCN	No	No
Xanodyne Pharm	DARVON COMPOUND-65	aspirin; caffeine; propoxyphene hydrochloride	CAPSULE;ORAL	010996-007	Mar 8, 1983		DISCN	No	No

DARVON COMPOUND Market Dynamics and Financial Trajectory

Last updated: September 1, 2026

DARVON COMPOUND was a legacy propoxyphene combination analgesic whose commercial value collapsed after regulators identified serious cardiac risks associated with propoxyphene. The FDA requested withdrawal of all propoxyphene products from the U.S. market in 2010, and the manufacturer agreed to remove DARVON, DARVOCET, and related products.[1] DARVON COMPOUND no longer has an active U.S. commercial market, current Orange Book protection, or a viable generic-entry opportunity.

Product-level revenue for DARVON COMPOUND was not separately disclosed in public company filings. Its financial trajectory must therefore be assessed through regulatory events, franchise-level disclosures, competitive substitution, and the withdrawal of propoxyphene products.

What was DARVON COMPOUND?

DARVON COMPOUND was a prescription oral analgesic containing propoxyphene hydrochloride with aspirin and caffeine. The product was marketed for the relief of mild to moderate pain. Propoxyphene was an opioid analgesic with lower potency than many later-generation opioid products.

DARVON COMPOUND formulation and active ingredients

Historical labeling identifies DARVON COMPOUND-65 as containing:

Attribute	Historical description
Brand	DARVON COMPOUND-65
Active opioid	Propoxyphene hydrochloride, 65 mg
Non-opioid ingredients	Aspirin and caffeine
Dosage form	Oral capsule
Therapeutic class	Opioid analgesic combination
Regulatory status	Prescription drug
U.S. status	Withdrawn from the market
Current availability	Not commercially available in the U.S.

The product differed from DARVOCET, which combined propoxyphene with acetaminophen. DARVON was generally associated with propoxyphene alone, while DARVON COMPOUND products used additional analgesic ingredients.

When did DARVON COMPOUND lose exclusivity?

DARVON COMPOUND lost practical commercial exclusivity long before its 2010 withdrawal. The product was an old small-molecule combination drug, and its core composition was not protected by commercially relevant, unexpired patents when the FDA removed propoxyphene products from the market.

Patent and exclusivity position

Protection category	DARVON COMPOUND status
New chemical entity exclusivity	Expired decades before withdrawal
Composition-of-matter patents	Historical protection, expired
Formulation patents	No known active protection supporting current sales
Method-of-use patents	No known active U.S. protection
Orphan-drug exclusivity	None
Pediatric exclusivity	None
Regulatory exclusivity	Expired
Current Orange Book patent protection	None of commercial significance

The product’s commercial life was therefore determined by prescribing demand, generic availability, safety concerns, and regulatory action rather than by patent expiry.

What triggered the withdrawal of DARVON COMPOUND?

The FDA requested withdrawal of propoxyphene products after reviewing evidence that the drug could cause serious and potentially fatal changes in cardiac electrical activity. The concern involved QT-interval prolongation, widened QRS complexes, and other conduction abnormalities.[1]

In November 2010, the FDA concluded that the risks of propoxyphene outweighed its benefits and requested that manufacturers voluntarily withdraw propoxyphene-containing products from the U.S. market.[1] The agency also instructed healthcare professionals to stop prescribing and dispensing the products and advised patients to contact their healthcare providers about alternative treatments.

The withdrawal affected the wider propoxyphene franchise rather than DARVON COMPOUND alone. Products covered by the regulatory action included:

• DARVON
• DARVOCET-N
• DARVOCET-N 50
• DARVOCET-N 100
• Generic propoxyphene products
• Propoxyphene combination analgesics

What was the FDA regulatory status of DARVON COMPOUND?

DARVON COMPOUND has no current FDA commercial status as an available prescription product. The relevant regulatory event was withdrawal from sale rather than ordinary patent-driven loss of market share.

FDA timeline

Year	Event
1970s and earlier	Propoxyphene products were marketed broadly in the U.S.
1978	FDA required labeling changes and warnings concerning overdose and dependence risks
2009	European regulators recommended withdrawal of propoxyphene products from the European market
2010	FDA concluded that cardiac risks outweighed benefits
November 2010	FDA requested voluntary withdrawal of all propoxyphene products
2011	U.S. market withdrawal was implemented
After 2011	No established commercial U.S. market remained for DARVON COMPOUND

The FDA action removed the product from normal commercial distribution. It did not create a new exclusivity period for alternative manufacturers.

What was the financial trajectory of DARVON COMPOUND?

The product likely moved through four financial phases: mature brand sales, generic erosion, safety-driven contraction, and complete revenue elimination after withdrawal.

Commercial phases

Mature brand period

DARVON products were established prescription analgesics during the period when propoxyphene occupied a significant position in outpatient pain treatment. Sales benefited from physician familiarity, broad prescribing, and limited competition from newer opioid and non-opioid therapies.

DARVON COMPOUND was part of a wider propoxyphene franchise. Public filings generally reported franchise or company-level results rather than revenue for each formulation, so standalone sales for DARVON COMPOUND cannot be reliably isolated.

Generic erosion

As the drug aged, generic propoxyphene products reduced the commercial value of branded versions. The primary financial effect was likely a decline in brand share and pricing power rather than a patent-cliff event tied to a newly approved generic.

Generic competition also reduced the value of the brand for licensing or acquisition. Any remaining value depended on prescription volume, manufacturing economics, distribution rights, and regulatory continuity.

Safety-driven contraction

Safety warnings and concern over overdose created a second source of decline. Propoxyphene had a relatively narrow safety margin in overdose, and risks increased when it was combined with alcohol, sedatives, or other central nervous system depressants.

The market contracted as prescribers shifted toward alternatives such as:

• Acetaminophen
• Nonsteroidal anti-inflammatory drugs
• Tramadol
• Hydrocodone combinations
• Oxycodone combinations
• Other short-acting opioid products

The relevant substitution was therapeutic rather than patent-based. Physicians did not wait for a competing patent to expire before changing treatment.

Withdrawal and revenue elimination

The 2010 FDA action ended legitimate U.S. commercial sales. After withdrawal, revenue from DARVON COMPOUND was effectively reduced to zero in the authorized U.S. market.

Any later financial activity would have been limited to inventory liquidation, regulatory closeout, litigation, manufacturing termination, or residual international rights. Those activities would not represent continuing product revenue.

How did DARVON COMPOUND compare with DARVOCET?

DARVOCET was the more commercially prominent propoxyphene combination because it paired propoxyphene with acetaminophen. DARVON COMPOUND used aspirin and caffeine, giving the products different tolerability and safety considerations.

Product	Opioid ingredient	Combination ingredient	Commercial relevance
DARVON	Propoxyphene	None in the basic product	Core propoxyphene brand
DARVON COMPOUND-65	Propoxyphene hydrochloride	Aspirin and caffeine	Combination analgesic
DARVOCET-N 50	Propoxyphene napsylate	Acetaminophen	Major propoxyphene combination
DARVOCET-N 100	Higher propoxyphene dose	Acetaminophen	Higher-strength combination

DARVOCET received greater public and commercial attention because of its broad use and the scale of the propoxyphene combination market. The FDA withdrawal applied to the active ingredient and therefore eliminated the commercial rationale for DARVON COMPOUND as well.

What patents protected DARVON COMPOUND?

No current U.S. patent estate is known to protect DARVON COMPOUND as a marketed product. Historical patents associated with propoxyphene, its salts, or early formulations expired long before the 2010 withdrawal.

Patent strength assessment

Patent factor	Assessment
Active composition patent	None of practical relevance
Active formulation patent	None identified as supporting current commercialization
Method-of-use patent	None identified as commercially relevant
Manufacturing patent	No barrier sufficient to support a modern market
Freedom to launch a generic before withdrawal	Broadly available, subject to FDA approval
Current patent litigation risk	None material
Post-withdrawal re-entry value	Negligible

The formulation itself did not create a meaningful barrier to competition. Aspirin, caffeine, and propoxyphene were established ingredients, and the product was not a biologic, complex drug-device combination, or specialized delivery system.

Were there Paragraph IV challenges to DARVON COMPOUND?

No commercially material Paragraph IV litigation is associated with DARVON COMPOUND in the post-2010 market because the FDA withdrawal removed the product’s viable U.S. market. Any earlier generic approvals or challenges would have occurred in a mature product environment with limited remaining brand value.

A Paragraph IV certification can challenge listed patents, but it does not overcome a regulatory withdrawal. Even if a generic applicant had obtained approval, commercial launch would not have created a sustainable market after the FDA concluded that propoxyphene’s risks outweighed its benefits.

What patent litigation affected DARVON COMPOUND?

The principal risk affecting the product was regulatory and product-liability exposure, not patent litigation. Propoxyphene manufacturers faced scrutiny over overdose deaths, dependence, accidental ingestion, and cardiac toxicity.

The withdrawal changed the economics of litigation. Once sales stopped, the commercial dispute shifted away from market exclusivity and toward:

• Product-liability claims
• Medical-monitoring issues
• Consumer injury allegations
• Regulatory compliance
• Manufacturing and distribution closeout
• Insurance and indemnity obligations

No active patent dispute is known to affect a current DARVON COMPOUND market because no such market exists.

Which companies challenged or replaced DARVON COMPOUND?

The competitive pressure came from therapeutic substitutes and generic propoxyphene manufacturers rather than a single branded challenger.

Competitive landscape

Before withdrawal, DARVON COMPOUND competed with:

• Generic propoxyphene combinations
• DARVOCET products
• Acetaminophen-based analgesics
• NSAIDs
• Tramadol
• Hydrocodone products
• Oxycodone products
• Non-pharmacologic pain treatments

After withdrawal, the key competitors were alternative analgesic classes. No company could lawfully replace DARVON COMPOUND with an equivalent propoxyphene product in the U.S. without addressing the FDA’s safety determination and obtaining an acceptable regulatory pathway.

Did licensing deals preserve DARVON COMPOUND value?

Licensing did not preserve the product’s U.S. commercial value after withdrawal. Rights to propoxyphene products changed among brand owners, manufacturers, and distributors over the product’s life, but the 2010 FDA action removed the central asset: lawful U.S. sales.

For a legacy analgesic, licensing value depends on:

1. An approved and marketable product.
2. A viable patient population.
3. Manufacturable supply.
4. Acceptable safety and labeling.
5. Defensible pricing or distribution rights.

DARVON COMPOUND failed the first two conditions after withdrawal. Any remaining licensing rights had little value outside residual markets, historical inventory, or litigation-related arrangements.

What generic entry risks existed for DARVON COMPOUND?

Before withdrawal, generic entry risk was high because the product was old, chemically simple, and exposed to established generic competition. After withdrawal, the issue changed from generic erosion to market prohibition.

Generic launch scenarios

Scenario	Commercial outcome
Generic launches before withdrawal	Low-margin mature-market competition
Generic launches after FDA withdrawal	Not commercially viable in the U.S.
Authorized reintroduction	Requires regulatory acceptance and new commercial investment
Reformulated propoxyphene product	High safety and approval risk
Non-propoxyphene substitute	More practical commercial pathway

A generic manufacturer could not create a sustainable opportunity merely by avoiding expired patents. The regulatory safety determination was the controlling barrier.

What manufacturing and intellectual-property barriers remain?

Manufacturing barriers are low in technical terms but high in regulatory and commercial terms.

Propoxyphene is a conventional small molecule, and the combination ingredients are widely available. The challenge is not complex biologic manufacturing, specialized delivery technology, or difficult formulation science. The barriers are:

• FDA acceptance of the active ingredient
• Demonstration of an acceptable benefit-risk profile
• Updated clinical and cardiac safety evidence
• Controlled-substance compliance
• Product-liability exposure
• Supply-chain and quality-system requirements
• Limited prescriber demand
• Competition from safer alternatives

The cost of rebuilding the product would therefore be driven more by regulatory evidence and commercial risk than by patents or manufacturing complexity.

What is the revenue exposure from DARVON COMPOUND today?

Current direct revenue exposure is effectively zero in the U.S. because the product was withdrawn. The more relevant financial exposures are historical and indirect:

Exposure	Current assessment
U.S. product revenue	None from authorized commercial sales
Patent royalties	No material current stream identified
Manufacturing revenue	Terminated or immaterial
Distribution revenue	Terminated or immaterial
Litigation expense	Historical or residual
Inventory value	De minimis after withdrawal
Re-entry value	Low due to regulatory risk
Substitution opportunity	Captured by other analgesic classes

The withdrawal may have affected the broader manufacturer’s portfolio, but public disclosures do not provide a reliable standalone DARVON COMPOUND revenue series.

How strong is the DARVON COMPOUND patent estate?

The patent estate is commercially obsolete. Its strength is effectively zero for present-day U.S. market protection.

The product has no known combination of active patents, regulatory exclusivity, or market barriers capable of supporting premium pricing. Its historical value came from age, physician familiarity, and distribution rather than durable intellectual property.

Key Takeaways

• DARVON COMPOUND was a propoxyphene hydrochloride, aspirin, and caffeine analgesic.
• Its patents and regulatory exclusivities expired long before its market withdrawal.
• The FDA requested withdrawal of all U.S. propoxyphene products in 2010 because cardiac risks outweighed benefits.[1]
• U.S. commercial revenue ended after the 2010-2011 withdrawal.
• Generic competition was already established before the withdrawal.
• No active Orange Book patent estate or meaningful Paragraph IV risk remains.
• The product’s principal legal exposure was product liability, not patent litigation.
• Reintroduction would face substantial FDA, safety, liability, and commercial barriers.
• Public filings do not provide a dependable standalone revenue history for DARVON COMPOUND.

FAQs About DARVON COMPOUND

Is DARVON COMPOUND still available by prescription?

No. Propoxyphene-containing products, including DARVON COMPOUND, were withdrawn from the U.S. market after the FDA’s 2010 safety action.

What replaced DARVON COMPOUND?

Prescribers generally shifted to acetaminophen, NSAIDs, tramadol, hydrocodone products, oxycodone products, and other pain-management options based on the patient’s clinical needs.

Did DARVON COMPOUND contain acetaminophen?

DARVON COMPOUND-65 was associated with aspirin and caffeine. DARVOCET products contained propoxyphene with acetaminophen and were a separate formulation family.

Could a company relaunch DARVON COMPOUND?

A relaunch would require FDA acceptance of the propoxyphene benefit-risk profile and approval of a new commercial pathway. Expired patents would not eliminate the regulatory and liability barriers.

Did DARVON COMPOUND have biosimilar competition?

No. DARVON COMPOUND was a conventional small-molecule drug, so biosimilar rules did not apply. Any historical competition involved generic drug approval pathways.

References

1. U.S. Food and Drug Administration. (2010, November 19). FDA recommends against continued use of propoxyphene. https://www.fda.gov/drugs/drug-safety-and-availability/fda-recommends-against-continued-use-propoxyphene

2. U.S. Food and Drug Administration. (2010, November 19). FDA announces voluntary withdrawal of propoxyphene from the U.S. market. https://www.fda.gov/drugs/drug-safety-and-availability/fda-announces-voluntary-withdrawal-propoxyphene-us-market

3. European Medicines Agency. (2009). European Medicines Agency recommends withdrawal of dextropropoxyphene-containing medicines. https://www.ema.europa.eu

4. U.S. Food and Drug Administration. (2011). Drug safety communication: FDA recommends against the continued use of propoxyphene. https://www.fda.gov/drugs/postmarket-drug-safety-information-patients-and-providers