United States Patent 4,569,937: Oxycodone-Ibuprofen Combination Claims, Expiration, and Patent Landscape

U.S. Patent No. 4,569,937 protects pharmaceutical compositions combining oxycodone, or an acceptable salt, with ibuprofen, or an acceptable salt, at an approximate weight ratio of 1:6 to 1:400. The patent also covers oral dosage forms, compositions containing pharmaceutical carriers, and methods of treating pain with the claimed combinations. The patent issued on February 11, 1986, and its ordinary 17-year term expired on February 11, 2003. It therefore does not create a current blocking right against generic or branded products.

The patent is technically relevant to oxycodone/ibuprofen products such as Combunox, which contains oxycodone hydrochloride 5 mg and ibuprofen 400 mg. That commercial ratio is 1:80 by stated ingredient weight and falls within the claimed range. The patent’s commercial significance today is historical and analytical rather than exclusionary.

What does U.S. Patent 4,569,937 protect?

U.S. Patent 4,569,937 claims a combination product and associated analgesic methods. Its central limitation is the combination of two active ingredients:

Oxycodone or a pharmaceutically acceptable salt; and
Ibuprofen or a pharmaceutically suitable salt.

The required weight ratio of oxycodone to ibuprofen is approximately 1:6 through 1:400.

Claim	Subject matter	Key limitation
1	Pharmaceutical composition	Oxycodone plus ibuprofen at an approximately 1:6 to 1:400 weight ratio
2	Oral dosage form	Depends on claim 1
3	Composition with carrier	Depends on claim 1 and adds a pharmaceutical carrier
4	Pain-treatment method	Administering claim 3 to a mammal
5	Pain-treatment method	Administering claim 1 to a mammal
6	Pain-treatment method	Administering claim 2 to a mammal

Claim 1 is the broadest composition claim. Claims 2 and 3 narrow claim 1 by specifying dosage-form and carrier characteristics. Claims 4 through 6 are method claims that depend on the corresponding composition claims.

How broad is the ratio limitation in Patent 4,569,937?

The claimed ratio extends from 1 part oxycodone to approximately 6 parts ibuprofen through 1 part oxycodone to approximately 400 parts ibuprofen.

Expressed as ibuprofen relative to oxycodone:

Oxycodone:ibuprofen ratio	Covered by claim 1?
1:5	Generally outside the stated range
1:6	At the lower endpoint
1:20	Within the range
1:80	Within the range
1:100	Within the range
1:400	At the upper endpoint
1:500	Generally outside the stated range

The word “about” gives the ratio some flexibility, but it does not remove the need for a meaningful relationship to the 1:6-to-1:400 range. A product materially outside the range would have a stronger non-infringement position, subject to claim construction and the doctrine of equivalents.

The ratio must also be assessed against the relevant form of each ingredient. Oxycodone may be present as oxycodone base or oxycodone hydrochloride, while ibuprofen may be present as the free acid or a salt. A product analysis should determine whether the ratio is calculated using labeled ingredient weight, active-moiety weight, molecular-equivalent weight, or another legally relevant basis.

Does Combunox fall within the composition claims?

Combunox contains oxycodone hydrochloride 5 mg and ibuprofen 400 mg per tablet. The stated ratio is 5:400, or 1:80. That ratio is inside the numerical range of claim 1.

The product also fits the general structure of claims 2 and 3:

It is an oral tablet, relevant to claim 2.
It contains inactive pharmaceutical ingredients and excipients, relevant to claim 3.

The formulation’s commercial relevance does not mean that Patent 4,569,937 currently blocks Combunox or a generic equivalent. The patent expired in 2003. Patent scope and present enforceability are separate questions.

The FDA approved Combunox under NDA 021389 for the short-term management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. The approved strength is oxycodone hydrochloride 5 mg and ibuprofen 400 mg per tablet (FDA, 2017).

When did U.S. Patent 4,569,937 expire?

Patent 4,569,937 issued on February 11, 1986. For a patent filed before June 8, 1995, the ordinary term was generally 17 years from issuance, subject to statutory adjustments and terminal disclaimers. On that basis, the patent expired on February 11, 2003.

Event	Date
Patent issued	February 11, 1986
Ordinary 17-year expiration	February 11, 2003
Current enforceable patent term	None

No current patent infringement action can be based solely on an expired patent. The expired patent may remain relevant as prior art, as evidence of technical development, or in evaluating later patent validity and obviousness.

What is the claim-by-claim scope of Patent 4,569,937?

Claim 1: Combination composition

Claim 1 requires the presence of both active ingredients. A composition containing oxycodone alone or ibuprofen alone does not satisfy the literal combination requirement.

The claim covers:

Oxycodone free base;
Oxycodone pharmaceutically acceptable salts, including oxycodone hydrochloride;
Ibuprofen;
Pharmaceutically acceptable ibuprofen salts; and
Combinations falling within the stated approximate ratio.

The claim does not appear limited to a particular tablet size, release profile, excipient system, indication, manufacturing process, or brand.

Claim 2: Oral dosage form

Claim 2 narrows claim 1 to an oral dosage form. Tablets, capsules, and other oral dosage presentations could fall within this category if they satisfy the underlying composition and ratio limitations.

The claim does not, on the supplied language, require immediate release, extended release, a specific dissolution profile, a particular tablet coating, or a defined dose.

Claim 3: Pharmaceutical carrier

Claim 3 adds a suitable pharmaceutical carrier. In practical terms, this captures conventional pharmaceutical formulations containing excipients, diluents, binders, lubricants, coatings, disintegrants, or related carriers.

Because most finished pharmaceutical products contain excipients, claim 3 would likely have covered ordinary commercial dosage forms during the patent term.

Claims 4 through 6: Methods of alleviating pain

The method claims require:

A mammal affected with pain;
An effective analgesic amount; and
Administration of the claimed composition.

Claim 4 is narrower because it requires the composition of claim 3. Claim 5 refers directly to claim 1. Claim 6 requires the oral dosage form of claim 2.

The method claims are not limited, on the supplied language, to a named pain condition, patient age, surgical procedure, dosing schedule, or treatment duration. The “synergistic” characterization in claim 1 may create a factual issue concerning the claimed combination’s pharmacological relationship, but the provided claim text does not state a specific quantitative synergy test.

What formulations are protected by Patent 4,569,937?

The patent’s formulation protection is broad at the ingredient-combination level and comparatively narrow at the ratio level. It does not appear to claim a proprietary delivery technology.

Potentially covered during the patent term were:

Immediate-release tablets;
Oral capsules;
Powders or granules for oral administration;
Oxycodone/ibuprofen compositions with conventional carriers;
Products using oxycodone hydrochloride and ibuprofen;
Products using different acceptable salts; and
Products within the 1:6-to-1:400 ratio.

The patent does not, based on the supplied claims, specifically protect:

A particular excipient;
A specific dissolution profile;
A controlled-release matrix;
A tablet-coating system;
A manufacturing process;
A packaging configuration;
A fixed 5 mg/400 mg dose; or
A particular brand name.

Later patents could have protected narrower formulation improvements, but such patents would need to be analyzed separately from Patent 4,569,937.

What was the Orange Book status of Patent 4,569,937?

Patent 4,569,937 cannot currently provide Orange Book exclusivity because it expired in 2003. The FDA Orange Book identifies patents and regulatory exclusivities associated with approved drug products, but an expired patent does not create a present statutory bar to ANDA approval.

For an oxycodone/ibuprofen product, Orange Book analysis should distinguish among:

Drug-substance patents;
Composition patents;
Formulation patents;
Method-of-use patents;
Pediatric exclusivity;
New chemical entity exclusivity;
Three-year clinical-investigation exclusivity; and
Any later-listed patents associated with the specific NDA.

Patent 4,569,937 is not a current basis for delaying approval of an abbreviated application. A generic applicant would not need to make a Paragraph IV certification against an expired patent. Paragraph IV certification is relevant when a listed patent remains unexpired and the applicant asserts that the patent is invalid, unenforceable, or not infringed under the Hatch-Waxman framework (21 U.S.C. § 355(j)(2)(A)(vii)(IV)).

Are there Paragraph IV challenges or generic-entry risks?

Patent 4,569,937 itself presents no current Paragraph IV risk because its term ended before the modern commercial lifecycle of many oxycodone/ibuprofen products.

Current generic-entry risk would instead depend on:

Whether the reference product has active Orange Book-listed patents;
Whether any listed method-of-use patents carry carve-out implications;
Whether the proposed generic matches the reference product’s dosage form and strength;
Controlled-substance requirements applicable to oxycodone;
FDA requirements for abuse-deterrence, labeling, and opioid risk controls;
Product-specific formulation patents; and
Commercial willingness to launch despite opioid-market restrictions.

A generic applicant could pursue an ANDA if it can demonstrate pharmaceutical equivalence and bioequivalence to the reference product. The expired combination patent would not prevent approval.

Does Patent 4,569,937 create biosimilar risk?

No. Biosimilar law applies to biological products, not small-molecule combinations such as oxycodone and ibuprofen. The relevant pathway is generally an ANDA under section 505(j) of the Federal Food, Drug, and Cosmetic Act, not a biosimilar application under section 351(k) of the Public Health Service Act.

The competitive threat is therefore generic substitution, not biosimilar entry.

How strong was the patent estate for oxycodone and ibuprofen?

Patent 4,569,937 was strong as a foundational combination patent because claim 1 covered the core two-drug composition across a wide ratio range. Its method claims extended protection to administration for pain treatment.

Its limitations were equally material:

The claims depended on both active ingredients being present.
The numerical ratio was central to composition coverage.
The patent did not claim oxycodone or ibuprofen individually.
It did not claim a specific commercial strength.
It did not claim a distinct delivery platform.
The entire estate expired in 2003.

The patent was therefore commercially meaningful during its term but has no remaining exclusionary value.

What patent litigation and settlement issues affect the product?

Patent 4,569,937 is too old to support a current infringement dispute. Any litigation involving a modern oxycodone/ibuprofen product would more likely concern later formulation patents, FDA approval strategy, labeling, controlled-substance compliance, or product-liability claims.

A historical Paragraph IV settlement involving a later patent would not revive Patent 4,569,937. Settlement terms must be tied to the specific asserted patents, products, and entry dates. The expired patent cannot independently support a delayed generic launch date.

How does this patent compare with later formulation and method patents?

Issue	Patent 4,569,937	Later formulation patent
Core subject	Oxycodone plus ibuprofen	Usually a narrower dosage-form or process improvement
Ratio	Approximately 1:6 to 1:400	May require a defined strength or release profile
Dosage form	Oral dosage form covered by dependent claim	Often tablet architecture or dissolution limitation
Manufacturing process	Not claimed in supplied claims	May claim granulation, coating, compression, or blending
Method of use	Broad pain-alleviation methods	May target a specific pain condition or regimen
Current status	Expired February 11, 2003	Must be checked patent by patent
Generic risk	None from this patent	Depends on expiration, listing, and claim scope

What geographic coverage did Patent 4,569,937 have?

The patent provided rights only in the United States. Corresponding foreign applications or patents, if any, would require separate family analysis. U.S. expiration did not automatically determine the term of foreign counterparts.

A global freedom-to-operate review should identify:

Priority applications;
International applications;
National-phase filings;
Issued foreign counterparts;
Continuations and divisionals;
Patent-term adjustments or extensions; and
Country-specific lapse and annuity records.

The U.S. patent’s expiration date cannot be used as a substitute for foreign legal-status analysis.

Key Takeaways

Patent 4,569,937 claims oxycodone/ibuprofen compositions at an approximate 1:6-to-1:400 weight ratio.
It also claims oral dosage forms, compositions with carriers, and methods of alleviating pain.
Combunox’s 5 mg oxycodone hydrochloride/400 mg ibuprofen strength corresponds to a 1:80 ratio and fits the central composition concept.
The patent issued February 11, 1986, and ordinarily expired February 11, 2003.
It creates no current Orange Book blocking right or Paragraph IV barrier.
The product is a small-molecule combination, so generic rather than biosimilar competition is relevant.
Current market protection, if any, would depend on later patents, regulatory exclusivities, labeling rights, or product-specific barriers.
Manufacturing and formulation freedom-to-operate cannot be inferred from this expired combination patent alone.

FAQs About U.S. Patent 4,569,937

Can a generic manufacturer launch an oxycodone/ibuprofen product despite Patent 4,569,937?

Yes. The patent expired in 2003 and cannot independently block generic entry.

Does the patent cover a 5 mg oxycodone and 400 mg ibuprofen tablet?

The 5:400 ratio is 1:80, which falls within the claimed approximate range. The patent covered that combination during its enforceable term.

Does Patent 4,569,937 cover oxycodone products without ibuprofen?

No. The composition claims require both oxycodone and ibuprofen.

Is an oxycodone/ibuprofen extended-release product automatically covered?

No. It would need to satisfy the claimed ingredients and ratio. Separate extended-release technology could raise distinct patent questions.

Can the expired patent be used to challenge a later oxycodone/ibuprofen patent?

Yes, as prior art where legally applicable. Expiration does not eliminate its potential evidentiary relevance to novelty or obviousness.

References

U.S. Patent No. 4,569,937. (1986). Pharmaceutical composition and method of alleviating pain. United States Patent and Trademark Office.
U.S. Food and Drug Administration. (2017). Combunox (oxycodone hydrochloride and ibuprofen) tablets, prescribing information. FDA.
United States Code, 21 U.S.C. § 355. (2024). New drugs and abbreviated new drug applications.
United States Patent and Trademark Office. (2024). Manual of Patent Examining Procedure, Chapter 2700: Patent terms and adjustments. USPTO.

Details for Patent: 4,569,937

Summary for Patent: 4,569,937