United States Patent 8,790,700: Claims, Scope, Expiration, and Drug Patent Landscape

US Patent No. 8,790,700 is a formulation patent directed to modified-release aqueous oral suspensions that combine ion-exchange-resin drug complexes, coated and uncoated resin particles, and free drug in one liquid product. The patent is commercially relevant to opioid-containing cough and cold formulations, particularly products containing hydrocodone or codeine with chlorpheniramine and, in certain claims, pseudoephedrine.

The patent does not claim hydrocodone, codeine, chlorpheniramine, dexchlorpheniramine, or pseudoephedrine as active ingredients alone. Its scope depends on a specific multipart formulation architecture and a defined polyvinyl acetate diffusion coating.

What does US Patent 8,790,700 protect?

US 8,790,700 protects a modified-release aqueous suspension containing three distinct drug populations:

A coated drug-ion exchange resin complex-matrix.
An uncoated drug-ion exchange resin complex.
Free, non-resin-complexed drug.

The coated matrix must contain a particulate drug-resin complex combined with a water-insoluble polymer, copolymer, or hydrophilic polymer. The matrix is then covered with a cured, water-permeable, water-insoluble, nonionic polymeric diffusion barrier.

The coating must contain:

Coating element	Claimed range or requirement
Polyvinyl acetate polymer	About 70% to about 90% by weight
Stabilizer	Required, amount not fixed in claim 1
Plasticizer	About 2.5% to about 20% by weight
Release profile	About 12 hours
Coating type	Aqueous-based, cured, water-permeable and water-insoluble
Matrix polymer content	About 3% to about 30% based on resin-complex weight
Particle size	Matrix capable of passing through a No. 40 mesh screen

The patent therefore covers a formulation platform rather than a single active ingredient.

Which claims are independent in US 8,790,700?

Claims 1, 19, 24, and 27 are independent composition claims.

Claim	Drug combination	Required free drug?	Key distinction
1	Codeine plus chlorpheniramine or dexchlorpheniramine, optionally pseudoephedrine	Yes	Coated complex-matrix, uncoated complex, and free drug
19	Hydrocodone plus chlorpheniramine or dexchlorpheniramine and pseudoephedrine	Yes	Requires all three drugs
24	Codeine plus chlorpheniramine or dexchlorpheniramine, optionally pseudoephedrine	No	Requires coated and uncoated complexes, but no separate free-drug component
27	Hydrocodone plus chlorpheniramine or dexchlorpheniramine and pseudoephedrine	No	Hydrocodone combination without the claim 19 free-drug limitation

Claims 1 and 24 are directed primarily to codeine combinations. Claims 19 and 27 are directed to hydrocodone combinations.

The independent claims are structurally similar but allocate the drug components differently. This claim redundancy creates multiple infringement theories against a product using the same resin technology but varying the amount of free drug.

How does the claim hierarchy operate?

The dependent claims narrow particle size, resin chemistry, coating composition, plasticizer selection, polymer content, and drug identity.

Resin limitations

Claims 3, 14, and 20 require or permit strong pharmaceutically acceptable ion-exchange resins. Claim 3 specifies a sulfonated styrene-divinylbenzene copolymer. That limitation is consistent with sulfonated polystyrene-divinylbenzene resins commonly used for drug-resin complexes.

A product using a different pharmaceutically acceptable ion-exchange resin could still fall within claim 1, 14, 19, 24, or 27 if the resin satisfies the broader functional and compositional language. A product using a non-sulfonated resin may avoid claims 3 and 20 but would not necessarily avoid the independent claims.

Polymer-matrix limitations

Claims 15, 16, 17, and 18 narrow the matrix:

Claim 15 requires a hydrophilic polymer.
Claim 16 specifies polyvinylpyrrolidone.
Claim 17 requires a water-insoluble polymer or copolymer.
Claim 18 specifies polyvinyl acetate with polyvinylpyrrolidone as stabilizer and a surfactant.

The patent distinguishes the polymer incorporated into the particulate matrix from the external diffusion-barrier coating. A formulation can therefore contain polyvinyl acetate in two technically different roles: as a matrix component under claim 18 and as the principal external coating polymer under claim 1.

Coating limitations

Claims 7 through 11 narrow the cured coating:

Claim	Limitation
7	Elongation factor of about 125% to about 400%
8	About 30% solids aqueous dispersion; polyvinyl acetate/polyvinylpyrrolidone dry ratio of about 10:1
9	Plasticizer at about 5% to about 10% of coating solids
10	Triacetin plasticizer
11	Sodium lauryl sulfate
12	Coating equal to about 35% to about 50% of matrix weight
22	Same 35% to 50% coating range for hydrocodone compositions
23	About 50% coating relative to matrix weight

These limitations give the patent several fallback positions. A generic developer may avoid the narrow claims by changing the plasticizer, surfactant, coating weight, or polymer ratio while still facing the broader independent claims.

What is the technical scope of the formulation?

The invention uses different release populations to shape the pharmacokinetic profile.

The coated resin complex provides delayed or extended release. The uncoated resin complex can provide a different release phase. Free drug supplies an immediate-release component. The combined system is intended to deliver an initial dose followed by prolonged release from the coated complex.

The formulation must be an aqueous oral suspension. A dry powder, tablet, capsule, nonaqueous solution, or purely coated-resin dosage form would not literally satisfy the composition claims.

The coating is not defined solely by polymer identity. It must also be:

Cured.
Water permeable.
Water insoluble.
Nonionic.
High tensile strength.
Plasticized.
Capable of producing about a 12-hour release profile.

Those functional limitations can create claim-construction disputes. The principal questions would include whether a competing coating is sufficiently water permeable, whether its release profile is approximately 12 hours, and how the "about" ranges should be construed.

What drug combinations are covered?

The patent covers two principal product classes.

Codeine compositions

Claims 1 and 24 cover codeine combined with:

Chlorpheniramine; or
Dexchlorpheniramine; and optionally
Pseudoephedrine.

Dependent claims 4 through 6 and 26 focus on codeine and chlorpheniramine without requiring pseudoephedrine.

Hydrocodone compositions

Claims 19 and 27 cover hydrocodone combined with:

Chlorpheniramine or dexchlorpheniramine; and
Pseudoephedrine.

The hydrocodone claims are narrower than the codeine claims because pseudoephedrine is mandatory in claims 19 and 27.

A hydrocodone/chlorpheniramine suspension without pseudoephedrine would not literally meet independent claims 19 or 27. It could still raise issues under other related patents or under the doctrine of equivalents, depending on the product and prosecution history.

What formulations are most exposed to infringement?

The highest-risk product profile is an aqueous extended-release suspension that has all of the following:

Hydrocodone, chlorpheniramine, and pseudoephedrine.
The same drug ingredients present in coated resin complexes and uncoated resin complexes.
A separate free-drug fraction, if claim 19 is implicated.
A sulfonated styrene-divinylbenzene resin.
A polyvinyl acetate-based cured coating.
Polyvinylpyrrolidone stabilizer.
Triacetin or a comparable plasticizer.
Approximately 12-hour release.
Particles passing through a No. 40 mesh screen.

A product using only free drug and coated resin particles would avoid claims requiring the uncoated complex. Conversely, a product using coated and uncoated complexes but no free drug would be more directly relevant to claims 24 and 27.

How strong is the patent estate?

Strengths

The patent has several claim-strength characteristics:

It claims the complete dosage-form architecture rather than only a coating material.
It covers both codeine and hydrocodone embodiments.
It includes claims with and without free drug.
It includes broad and narrow resin limitations.
It claims functional release performance in combination with structural elements.
It has dependent claims directed to commercially practical excipients, including polyvinylpyrrolidone, triacetin, and sodium lauryl sulfate.

Weaknesses

The patent also has material design-around and validity vulnerabilities:

The independent claims are highly combination-specific.
The 12-hour release limitation may require analytical testing and could create enablement or indefiniteness disputes.
"About" ranges may be challenged if the specification does not provide a clear boundary.
Prior art involving drug-resin complexes, polyvinyl acetate coatings, and sustained-release liquid suspensions may be combined in an obviousness challenge.
A competing product can potentially alter the resin, matrix polymer, coating polymer, plasticizer, particle size, or free-drug distribution.
The claim language requires a suspension. A different dosage form may avoid literal infringement.

The strongest enforcement position would likely be against a product that copies the resin chemistry and coating system while retaining the same drug distribution and release profile.

When does US 8,790,700 lose exclusivity?

The patent issued on July 29, 2014. Its ordinary US patent term is measured from the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, and any applicable patent-term extension. Public patent records identify the patent as part of a continuation-based formulation patent family associated with Tris Pharma.

The commonly used statutory expiration estimate for this family is in or around January 2026, subject to the patent’s recorded term adjustment and any terminal disclaimer. The patent is therefore at or near the end of its ordinary US patent term in 2026.

Patent expiration does not itself eliminate FDA regulatory exclusivity, controlled-substance requirements, product-specific labeling restrictions, or later-expiring related patents.

What is the Orange Book status?

A patent number alone does not establish Orange Book listing status. Orange Book relevance depends on whether the patent was submitted for a specific approved NDA and accepted by FDA as claiming:

The approved drug substance.
The approved drug product.
A formulation or composition.
An approved method of use.

The claims of US 8,790,700 are composition claims directed to a particular liquid formulation. They are not drug-substance claims. If listed, the patent would be most relevant to an approved extended-release aqueous suspension containing the claimed opioid, antihistamine, and decongestant combination.

The patent is not relevant to every hydrocodone, codeine, chlorpheniramine, or pseudoephedrine product. A listed formulation patent applies only to the NDA product and the approved formulation scope identified in the FDA listing.

What Paragraph IV challenges could arise?

An ANDA applicant challenging an Orange Book-listed patent could assert that:

The proposed product does not contain both coated and uncoated resin complexes.
The drug is not bound to the claimed water-insoluble ion-exchange resin.
The coating does not contain 70% to 90% polyvinyl acetate.
The coating is not cured, water-insoluble, nonionic, or water permeable.
The formulation does not provide approximately 12-hour release.
The proposed product lacks free drug, where required by claim 1 or 19.
Pseudoephedrine is absent from a hydrocodone product, avoiding claims 19 and 27.
The product is not an aqueous suspension.

Validity challenges would likely focus on obviousness over earlier drug-resin complex systems and aqueous controlled-release suspensions. Anticipation would require a single reference disclosing all material elements, including the specific drug combination, matrix, coating composition, particle characteristics, and release profile.

No conclusion on Paragraph IV litigation can be drawn from the claim text alone. The operative inquiry is the FDA patent listing for the relevant NDA and the ANDA applicant’s certification.

Which products and companies are commercially relevant?

The claimed drug combinations overlap with the technical field occupied by extended-release cough and cold products such as Tussionex-type hydrocodone/chlorpheniramine suspensions and combination products containing hydrocodone, chlorpheniramine, and pseudoephedrine.

The relevant commercial entities can include:

Entity type	Relevance
Tris Pharma	Patent owner and formulation-technology developer associated with modified-release liquid dosage forms
NDA holder	Controls the approved product and Orange Book submissions
Generic manufacturers	Potential ANDA applicants
Contract manufacturers	May produce resin complexes, coated particles, or finished suspensions
Resin suppliers	Potential source of ion-exchange materials and manufacturing know-how

A generic launch decision must evaluate more than US 8,790,700. The relevant freedom-to-operate review should include related continuation patents, earlier resin-complex patents, opioid formulation patents, FDA exclusivity, controlled-substance requirements, and state-level product restrictions.

Does the patent create biosimilar risk?

No. Biosimilar risk is not applicable because the claimed products are small-molecule oral suspensions, not biologics. The competitive pathway is 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 principal regulatory risk is generic substitution and Paragraph IV litigation.

What manufacturing and IP barriers remain?

The manufacturing barrier is meaningful even if the patent expires. A commercially consistent product requires control of:

Drug loading onto the ion-exchange resin.
Resin particle-size distribution.
Polymer incorporation into the particulate matrix.
Coating thickness and coating weight.
Cure conditions.
Plasticizer concentration.
Suspension sedimentation and redispersibility.
Drug release across the shelf-life period.
Uniformity of free and complexed drug fractions.

The patent’s process detail may create practical know-how barriers separate from its enforceable claims. A competitor can avoid literal infringement while still facing development risk from the need to reproduce a stable, palatable, 12-hour liquid suspension.

How does US 8,790,700 compare with a conventional extended-release suspension patent?

Issue	US 8,790,700	Conventional extended-release suspension
Dosage form	Aqueous oral suspension	May be suspension, solution, tablet, or capsule
Release mechanism	Coated and uncoated drug-resin complexes plus free drug	Usually one controlled-release mechanism
Coating	Cured polyvinyl acetate-based diffusion barrier	May use ethylcellulose, methacrylate polymers, lipids, or other barriers
Drug combinations	Specific opioid-antihistamine-decongestant combinations	Often one active ingredient
Particle limitation	No. 40 mesh limitation in key claims	Not necessarily
Release target	About 12 hours	Product-dependent
Design-around options	High, because many structural limitations are cumulative	Depends on claim breadth

Key Takeaways

US 8,790,700 is a formulation patent, not an active-ingredient patent.
Its core invention combines coated resin complexes, uncoated resin complexes, and, in some claims, free drug in an aqueous suspension.
Claims 1 and 24 focus on codeine combinations.
Claims 19 and 27 focus on hydrocodone, chlorpheniramine or dexchlorpheniramine, and pseudoephedrine.
Polyvinyl acetate, polyvinylpyrrolidone, plasticizer, cured coating, particle size, and approximately 12-hour release are central limitations.
The patent has multiple design-around paths because the claims require a dense combination of structural and functional elements.
Its ordinary US patent term is generally expected to end in or around January 2026, subject to the recorded patent-term calculation.
Biosimilar risk does not apply.
Generic risk depends on Orange Book listing, related family patents, FDA exclusivity, and the proposed product’s resin and coating architecture.

FAQs About US Patent 8,790,700

Does US 8,790,700 cover Tussionex?

It may be relevant to a Tussionex-type extended-release hydrocodone/chlorpheniramine suspension, but infringement depends on the specific product composition, resin complexes, coating, free-drug content, and Orange Book listing.

Can a generic avoid US 8,790,700 by removing pseudoephedrine?

Removing pseudoephedrine can avoid the hydrocodone limitations in claims 19 and 27, which require pseudoephedrine. It does not automatically avoid the codeine claims or related patents.

Is polyvinyl acetate mandatory for every claim?

Polyvinyl acetate is mandatory in the independent claims because the cured diffusion barrier must contain about 70% to 90% polyvinyl acetate polymer. Claims 8 and 18 add narrower polyvinylpyrrolidone and formulation requirements.

Does the patent cover a tablet containing the same drugs?

No. The independent claims require a modified-release aqueous oral liquid suspension. A tablet would not literally satisfy the claimed dosage-form limitation.

What is the most important validity issue?

The principal validity issues are likely obviousness and claim construction. Earlier references combining ion-exchange-resin complexes with polymeric diffusion coatings could be used to challenge whether the claimed drug combinations, coating ranges, particle sizes, and release profile were nonobvious.

References

United States Patent No. 8,790,700, “Modified release aqueous oral liquid suspensions.” U.S. Patent and Trademark Office. Issued July 29, 2014.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Food and Drug Administration. (2024). Tussionex Pennkinetic extended-release suspension prescribing information. FDA.
U.S. Food and Drug Administration. (2024). Approved drug products and patent and exclusivity information. FDA.
United States Code, 35 U.S.C. §§ 154, 156.
United States Code, 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Tris Pharma Inc	TUZISTRA XR	chlorpheniramine polistirex; codeine polistirex	SUSPENSION, EXTENDED RELEASE;ORAL	207768-001	Apr 30, 2015		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Patented / Exclusive Use	>Submissiondate

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	E536867	⤷ Start Trial
Australia	2007227569	⤷ Start Trial
Brazil	PI0709606	⤷ Start Trial
Canada	2645855	⤷ Start Trial
China	101400343	⤷ Start Trial
China	102488652	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,790,700

Which drugs does patent 8,790,700 protect, and when does it expire?

Summary for Patent: 8,790,700