Details for Patent: 4,534,974

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Summary for Patent: 4,534,974

Title:	Pharmaceutical compositions with codeine
Abstract:	Compositions for the relief of pain, muscle spasm and limited mobility associated with acute painful muscoloskeletal conditions are disclosed. Such compositions comprise in combination, a N-monosubstituted-2, 2-dialkyl-1, 3-propanediol dicarbamate, aspirin and codeine.
Inventor(s):	Miwon S. Kim
Assignee:	Meda Pharmaceuticals Inc
Application Number:	US06/636,192
Patent Claim Types: see list of patent claims	Use; Composition; Dosage form;

United States Patent 4,534,974: Claim Scope, Expiration, Orange Book Status, and Generic Entry Risk

U.S. Patent No. 4,534,974 covers a fixed-dose oral combination of aspirin, carisoprodol, and codeine phosphate, marketed historically as Soma Compound with Codeine. Its claims are directed to the composition in unit-dose form and to oral treatment of acute painful musculoskeletal conditions. The patent issued on August 13, 1985, and its 17-year post-grant term expired in 2002. The patent therefore does not create a current barrier to generic manufacture, ANDA approval, or launch.

The most commercially relevant claimed ratio is 16 parts aspirin, 10 parts carisoprodol, and 1 part codeine phosphate. A corresponding product strength is commonly identified as aspirin 325 mg, carisoprodol 200 mg, and codeine phosphate 16 mg.

What drug and formulation does U.S. Patent 4,534,974 protect?

The patent protects a three-active-ingredient combination:

Component	Chemical or regulatory identity	Function in the claimed combination
Aspirin	Acetylsalicylic acid	Analgesic and anti-inflammatory agent
N-propyl-2-methyl-2-propyl-1,3-propanediol dicarbamate	Carisoprodol	Centrally acting skeletal muscle relaxant
Codeine phosphate	Opioid analgesic salt	Analgesic component

The claims use the older chemical description of carisoprodol rather than the modern generic name. This matters for claim interpretation: “N-propyl-2-methyl-2-propyl-1,3-propanediol dicarbamate” is the active ingredient now known as carisoprodol.

The claimed therapeutic target is the treatment and relief of pain, muscle spasm, and limited mobility associated with acute painful musculoskeletal conditions. The specification and claims concern oral systemic treatment, not topical administration, injection, transdermal delivery, or a carisoprodol-only product.

What are the independent and dependent claims in Patent 4,534,974?

Claims 1 and 3 are the principal independent claims. Claims 2 and 4 narrow those claims to a specific ratio.

Claim 1: Unit-dose therapeutic composition

Claim 1 requires all of the following:

1. A therapeutic composition.
2. A unit dosage form.
3. Intended for systemic treatment and relief of pain, muscle spasm, and limited mobility associated with acute painful musculoskeletal conditions.
4. Aspirin in an amount of about 15 to about 20 parts by weight.
5. Carisoprodol in an amount of about 10 to about 15 parts by weight.
6. Codeine phosphate in an amount of about 1 to about 2 parts by weight.

The claim is a composition claim. It does not require a particular tablet size, excipient, coating, dissolution profile, manufacturing process, or brand name, provided the accused product falls within the claimed active-ingredient ratios and unit-dose limitations.

Claim 2: Narrow 16:10:1 composition

Claim 2 narrows claim 1 to a composition containing:

• 16 parts aspirin;
• 10 parts carisoprodol; and
• 1 part codeine phosphate.

This is a 16:10:1 weight ratio. The claim is narrower than claim 1 because it identifies a specific proportion rather than the broader numerical ranges.

A product containing 325 mg aspirin, 200 mg carisoprodol, and 16 mg codeine phosphate has the following approximate ratio:

Active ingredient	Amount	Normalized ratio
Aspirin	325 mg	16.25
Carisoprodol	200 mg	10
Codeine phosphate	16 mg	0.8

The precise commercial strength and the claimed ratio should be assessed using the patent’s measurement convention, including whether the specification treats the listed amounts as active ingredients, salts, or formulation quantities. The commercial product is generally associated with the same formulation concept, but exact infringement analysis would require product-specific assay and labeling data.

Claim 3: Oral treatment method

Claim 3 requires:

1. A method of systematically treating and relieving the specified symptoms.
2. A warm-blooded animal in need of treatment.
3. Oral administration.
4. A therapeutic amount.
5. A composition consisting essentially of the three specified active ingredients within the stated ranges.

The “consisting essentially of” language is significant. It generally permits components that do not materially alter the basic and novel characteristics of the claimed combination, such as conventional excipients, but it can restrict additional active ingredients or additives that materially change the claimed combination.

Claim 4: Narrow method claim

Claim 4 limits claim 3 to the 16:10:1 formulation. It covers oral administration of the specified ratio for the claimed musculoskeletal indications.

How broad are the numerical ranges in the patent claims?

Claim 1 covers compositions within these ranges:

Ingredient	Claimed range
Aspirin	15-20 parts by weight
Carisoprodol	10-15 parts by weight
Codeine phosphate	1-2 parts by weight

The ranges are independent numerical limitations. A composition does not need to use the exact commercial 16:10:1 ratio to fall within claim 1. For example, a 15:10:1 composition is within the literal ranges, as is a 20:15:2 composition, subject to the ordinary interpretation of “about.”

The word “about” introduces some tolerance around the stated endpoints. Its legal effect depends on the specification, prosecution history, analytical precision, and the accused product’s distance from the endpoint. It does not convert the claims into an unlimited range.

Claim 2 is materially narrower. It is directed to the specific 16:10:1 formulation and does not cover every formulation within the broader claim 1 ranges.

What dosage forms are covered by Patent 4,534,974?

The patent expressly requires a “unit dosage form” in claim 1. The likely covered dosage forms include:

• Tablets;
• Capsules;
• Other discrete oral units containing one therapeutic dose.

The claims do not expressly require a tablet, capsule, immediate-release profile, coating, or particular excipient system. A unit-dose tablet or capsule could fall within the composition claims if it contains the required active ingredients in the claimed ratio.

The patent does not expressly claim:

• Extended-release carisoprodol;
• Abuse-deterrent formulations;
• Enteric coating;
• Liquid formulations;
• Injectable products;
• Transdermal systems;
• Separate co-packaged products;
• A carisoprodol-only product;
• Aspirin-codeine combinations without carisoprodol.

A liquid or multi-dose bottle would face a claim 1 issue because the claim requires a unit dosage form. The method claims are broader in dosage-form language, but they require oral administration of a composition meeting the active-ingredient ranges.

Does the patent cover all aspirin, carisoprodol, and codeine products?

No. Patent 4,534,974 is not a product-by-ingredient monopoly over each active ingredient.

It does not individually cover:

• Aspirin;
• Carisoprodol;
• Codeine phosphate;
• Aspirin plus carisoprodol without codeine;
• Aspirin plus codeine without carisoprodol;
• Carisoprodol plus codeine without aspirin.

The protected subject matter is the specified three-drug combination, in the claimed proportions, for the claimed composition and treatment uses.

The patent also does not appear to claim a particular polymorph, crystalline form, impurity profile, synthetic process, tablet coating, packaging configuration, or manufacturing equipment.

When did U.S. Patent 4,534,974 expire?

The patent issued on August 13, 1985. Because it is a pre-June 8, 1995 patent, its ordinary term was generally 17 years from grant under the transition framework applicable to older U.S. patents. On that basis, the patent expired on August 13, 2002, absent an unusual term adjustment or enforceable extension.

Event	Date
Patent grant	August 13, 1985
Ordinary 17-year post-grant expiration	August 13, 2002
Current enforceability	None based on the original patent term

Patent term restoration under 35 U.S.C. § 156 is generally associated with qualifying regulatory review delays, but the available record for this old combination patent does not indicate a current extension. The patent is therefore relevant as historical prior art and as a record of the original branded product strategy, not as an active exclusion right.

What is the Orange Book status of the aspirin-cariso­prodol-codeine combination?

The FDA Orange Book concerns approved drug products, therapeutic equivalence, patents submitted by NDA holders, and regulatory exclusivity. It does not revive expired patents.

The branded combination historically associated with the patent was Soma Compound with Codeine. The product contained aspirin, carisoprodol, and codeine phosphate and was approved through the NDA framework. Any historical Orange Book listing for Patent 4,534,974 would no longer block approval or launch after the 2002 patent expiration. FDA’s Orange Book also distinguishes patent listings from regulatory exclusivity, which expires under separate rules.[1]

The current commercial and regulatory status of a specific product may vary by NDA holder, marketing status, and FDA withdrawal records. The patent itself supplies no current Orange Book protection.

Were there Paragraph IV challenges to Patent 4,534,974?

A Paragraph IV certification is relevant only while an applicable patent is listed and unexpired. Under the Hatch-Waxman framework, an ANDA applicant may certify that a listed patent is invalid, unenforceable, or will not be infringed. A Paragraph IV notice can trigger patent litigation and, in qualifying circumstances, a 30-month stay of approval under 21 U.S.C. § 355(j).[2]

For Patent 4,534,974, the practical relevance of Paragraph IV litigation ended when the patent expired in 2002. An applicant seeking approval after expiration would not need to overcome the expired patent through a current Paragraph IV strategy. Historical ANDA certifications or litigation records may exist, but the expired patent cannot support a present injunction or approval stay.

The available claims do not indicate a separate unexpired continuation patent. No current Paragraph IV threat can be inferred from Patent 4,534,974 alone.

What patent litigation affected the product?

Patent 4,534,974 could have supported infringement litigation before August 2002 against a product that combined aspirin, carisoprodol, and codeine phosphate in the claimed ratios. The strongest asserted claims would likely have been:

• Claim 1 for a unit-dose composition within the stated ranges;
• Claim 2 for the 16:10:1 formulation;
• Claim 3 for oral treatment using the claimed range-based composition;
• Claim 4 for oral treatment using the 16:10:1 ratio.

After expiration, infringement claims under this patent became moot for new conduct. Any historical litigation would need to be analyzed separately for filing date, accused product, damages period, validity defenses, prosecution history, and settlement terms.

No settlement agreement, license, or consent decree can be established from the claims alone. Patent ownership, litigation, and licensing must be distinguished from FDA approval records and product labeling.

How strong was the patent estate?

The estate was narrow but commercially focused.

Factor	Assessment
Active ingredient scope	Narrow; limited to aspirin, carisoprodol, and codeine phosphate
Ratio scope	Moderate under claim 1; narrow under claims 2 and 4
Dosage-form scope	Focused on unit-dose oral products
Method scope	Limited to specified musculoskeletal treatment and oral administration
Manufacturing protection	None apparent from the quoted claims
Formulation technology	No clear excipient, release, coating, or delivery-system protection
Current enforceability	None; patent expired in 2002
Biosimilar relevance	None; this is a small-molecule combination
Generic risk today	Regulatory and controlled-substance risk, not patent infringement risk

The claims were potentially useful against a directly substitutable fixed-dose product. They would have been less effective against a product sold as separate components, a different active-ingredient ratio outside the claims, or a product lacking the claimed unit-dose configuration, depending on the method of use and evidence of induced infringement.

What generic launch risks exist today?

Patent risk from U.S. Patent 4,534,974 is effectively zero because the patent expired more than two decades ago. Current launch risks arise from other sources:

1. FDA approval requirements for the combination product.
2. Controlled-substance requirements for codeine and carisoprodol.
3. Labeling and abuse-liability controls.
4. Demonstration of pharmaceutical equivalence and bioequivalence.
5. Manufacturing controls for a combination containing an opioid.
6. Product-specific regulatory status, including whether an ANDA reference product remains available.
7. Any later patents or regulatory exclusivities not connected to Patent 4,534,974.
8. State prescribing, monitoring, and controlled-substance laws.

Because the product is a small-molecule combination, a generic applicant would generally use the ANDA pathway if an appropriate reference listed drug and product-specific FDA pathway are available. A 505(b)(2) application could be relevant where the proposed product differs materially from the reference product in dosage form, strength, route, or other features.[3]

Does the product face biosimilar competition?

No. Biosimilar provisions under the Public Health Service Act apply to biological products, not aspirin, carisoprodol, or codeine phosphate. Competition would arise through generic-drug pathways, not biosimilar applications.[4]

The relevant competitive products would include:

• Generic fixed-dose aspirin/carisoprodol/codeine products;
• Separate generic carisoprodol, aspirin, and codeine products;
• Other skeletal muscle relaxant combinations;
• Non-opioid analgesic regimens;
• Products containing carisoprodol without aspirin or codeine.

How does Patent 4,534,974 compare with other possible barriers?

Barrier type	Relevance to this patent
Active-ingredient patent	Not the focus of the claims
Combination patent	Core protection
Formulation patent	Not apparent from the quoted claims
Method-of-use patent	Claims 3 and 4 provide limited method protection
Manufacturing patent	Not claimed
Device patent	Not relevant
Regulatory exclusivity	Separate from the patent and historically expired
Controlled-substance regulation	Current commercial constraint
Biosimilar exclusivity	Not applicable

Key Takeaways

• U.S. Patent 4,534,974 claims a fixed-dose combination of aspirin, carisoprodol, and codeine phosphate.
• The broad composition range is approximately 15-20 parts aspirin, 10-15 parts carisoprodol, and 1-2 parts codeine phosphate.
• Claims 2 and 4 focus on the narrower 16:10:1 ratio.
• Claims 1 and 2 target unit-dose compositions; claims 3 and 4 target oral treatment methods.
• The patent does not claim carisoprodol, aspirin, or codeine individually.
• It does not provide clear protection for manufacturing processes, excipients, release mechanisms, polymorphs, or delivery devices.
• The patent issued on August 13, 1985, and its ordinary term expired on August 13, 2002.
• No current Paragraph IV or Orange Book barrier can arise from this expired patent.
• The product is a small-molecule combination, so generic competition, not biosimilar competition, is the relevant pathway.
• Current commercial risk is driven by FDA approval, controlled-substance regulation, labeling, manufacturing, and any later product-specific rights.

FAQs About U.S. Patent 4,534,974

Can a company launch a generic product with the same 16:10:1 ratio?

Yes, Patent 4,534,974 no longer prevents launch because its patent term expired in 2002. The applicant must still satisfy FDA approval, bioequivalence, labeling, manufacturing, and controlled-substance requirements.

Does the patent cover Soma Compound with Codeine by brand name?

No. The claims cover the active-ingredient combination, ratios, dosage form, and treatment method. They do not depend on the brand name.

Can a formulation with different excipients avoid the patent?

Changing excipients would not necessarily avoid claims 1 or 2 if the product remained a covered unit-dose composition with the claimed active ingredients and ratios. Excipients are generally secondary to the claimed active-ingredient limitations.

Would separate aspirin, carisoprodol, and codeine products infringe the composition claims?

Separate products generally would not meet the unit-dose composition requirement of claims 1 and 2. Method-of-use exposure would depend on the specific administration conduct, product instructions, and proof of infringement.

Is codeine phosphate dosage regulated separately from patent protection?

Yes. Codeine phosphate is subject to controlled-substance regulation, and carisoprodol is also federally controlled. Those regulatory requirements remain relevant even though the patent has expired.

References

1. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book

2. U.S. Food and Drug Administration. (2024). Abbreviated new drug application (ANDA): Paragraph IV certifications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/paragraph-iv-certifications

3. U.S. Food and Drug Administration. (2024). Applications covered by section 505(b)(2). https://www.fda.gov/drugs/abbreviated-new-drug-application-anda

4. U.S. Congress. (2010). Biologics Price Competition and Innovation Act of 2009, Pub. L. No. 111-148, §§ 7001-7003, 124 Stat. 119.

5. United States Patent and Trademark Office. (1985). U.S. Patent No. 4,534,974: Therapeutic compositions containing aspirin, carisoprodol and codeine phosphate.

Drugs Protected by US Patent 4,534,974

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate