US Patent 8,791,127: Claim Scope, Acyclovir Buccal Formulation, and Patent Landscape

US Patent 8,791,127 protects a specific architecture for a prolonged-release, mucoadhesive oral formulation. The strongest commercial embodiment is an acyclovir buccal tablet containing sodium lauryl sulfate, natural milk proteins, hypromellose, and a separately granulated antiviral core. The patent is materially narrower than a general claim to oral acyclovir or mucoadhesive drug delivery.

The principal enforcement risk is directed to formulations that combine all of the following: antiviral-loaded primary granules, sodium lauryl sulfate or another alkali metal alkyl sulfate, a bioadhesive polymer dispersed outside the primary granules, and a sustained-release polymer. Claims 16 through 20 most closely define the likely commercial acyclovir product profile.

What does US Patent 8,791,127 protect?

The patent has three independent claim categories:

Claim category	Independent claims	Protected subject matter
Composition	Claim 1	Prolonged-release mucoadhesive formulation
Manufacturing process	Claim 24	Granulation, blending, and compression sequence
Treatment method	Claim 28	Treating mucosal disease by administering the formulation to oral mucosa

Claim 1 is the principal composition claim. It requires a formulation comprising:

An antiviral agent.
A diluent.
An alkali metal alkyl sulfate.
A binding agent.
At least one bioadhesive polymer.
At least one sustained-release polymer.
Primary granules containing the antiviral agent, diluent, alkali metal alkyl sulfate, and binding agent.
A bioadhesive polymer dispersed in the finished formulation.

The use of “comprising” makes the claim open-ended. An accused product can contain additional excipients and still fall within the claim if every required element is present. The open-ended structure does not eliminate the need to prove the specific granulation and polymer-distribution limitations.

How do claims 1 through 30 divide the patent scope?

Composition claims 1 through 23

Claims 2 through 23 narrow claim 1 through ingredient, concentration, particle-size, and manufacturing limitations.

Claims	Limitation
2	No more than 5% polyvinylpyrrolidone
3	Bioadhesive polymer is not in the primary granules
4	Alkali metal alkyl sulfate at 2% to 6% by weight
5	Bioadhesive polymer at 10% to 40% by weight
6	Sustained-release polymer at 10% to 40% by weight
7	Binding agent at 0.5% to 5% by weight
8	Binding agent is polyvinylpyrrolidone
9-10	Bioadhesive polymer is a natural protein, specifically natural milk protein
11-13	Antiviral is acyclovir, at 10-200 mg or 50-100 mg
14-15	Broad and narrower composition ranges
16	Sodium lauryl sulfate, natural milk proteins, and hypromellose
17-18	Acyclovir and/or polyvinylpyrrolidone added to claim 16
19-20	50 mg or 100 mg acyclovir with specified excipient ranges
21	Formulation is devoid of starch
22	Predominant primary-granule fraction is below 125 micrometers
23	Formulation is compressed from primary granules, bioadhesive polymer, and sustained-release polymer

The most commercially significant chain is:

Claim 1 → claim 15 → claim 16 → claim 17 or 18

A second important chain is:

Claim 1 → claim 19 → claim 20

These claims cover an acyclovir formulation containing sodium lauryl sulfate, natural milk proteins, and hypromellose. Claim 19 is commercially important because it specifies the 50 mg and 100 mg acyclovir strengths associated with a buccal-tablet product profile.

Manufacturing claims 24 through 27

Claim 24 protects a three-stage preparation method:

Granulating the antiviral, diluent, alkali metal alkyl sulfate, and binding agent.
Blending the granulated material with the bioadhesive and sustained-release polymers.
Compressing the blend.

Claims 25 through 27 narrow the method to natural proteins, natural milk proteins, and acyclovir.

This process limitation distinguishes the patent from a product claim based solely on final composition. A manufacturer may avoid a process claim if it uses a different sequence, such as co-processing all excipients in one granulation step, direct compression, spray drying, or a granulation process that places the bioadhesive polymer inside the primary granules. Product claims 1 and 16 through 20 may still present exposure even if claim 24 is avoided.

Treatment claims 28 through 30

Claims 28 through 30 cover administration of the claimed formulation to the oral mucosa of a human patient for treatment of a mucosal disease.

The treatment claims are narrower than a claim to treating herpes infection generally. They require use of the patented formulation and administration to oral mucosa. The claims do not expressly limit the mucosal disease to herpes labialis, although acyclovir makes herpes-related treatment the most commercially relevant application.

Which claim limitations create the principal infringement issues?

The most important limitations are structural rather than merely ingredient-based.

Primary granules

The antiviral, diluent, alkali metal alkyl sulfate, and binding agent must be present in primary granules. A product containing the same ingredients in a homogeneous matrix may not satisfy this limitation unless the granulation structure can be demonstrated.

The patent does not define primary granules solely by particle size in claim 1. Claim 22 adds a narrower limitation requiring the predominant fraction to be below 125 micrometers. Particle-size evidence can therefore affect claim scope, but failure to meet claim 22 does not necessarily avoid claim 1.

Separation of the bioadhesive polymer

Claim 3 expressly requires that the bioadhesive polymer not be in the primary granules. Claim 1 requires the bioadhesive polymer to be dispersed in the formulation but does not expressly impose the claim 3 exclusion.

A product can therefore raise two separate issues:

Whether the bioadhesive polymer is present in the finished dosage form.
Whether it is physically excluded from the primary granules.

The location of the polymer is likely to require manufacturing records, microscopy, process documentation, or formulation-development data.

Sodium lauryl sulfate

Sodium lauryl sulfate is the most commercially relevant alkali metal alkyl sulfate under claims 16 through 20. Claim 1 is broader and can cover other alkali metal alkyl sulfates, subject to the remaining limitations.

The concentration ranges matter:

Claim 1 has no express concentration limitation.
Claim 4 narrows sodium lauryl sulfate or another alkali metal alkyl sulfate to 2% to 6%.
Claim 14 covers 1% to 10%.
Claim 19 covers 2% to 10%.
Claim 16 uses the narrower 2% to 6% limitation inherited from claim 15.

A formulation using sodium lauryl sulfate below 2% or above 10% may avoid the narrower claims while remaining exposed under claim 1, depending on the remaining elements.

Natural milk proteins

Claims 10, 16, and 19 focus on natural milk proteins. The claims do not identify a single protein in the supplied text. Casein, whey proteins, and mixtures may fall within the natural milk-protein language if they satisfy the claim construction adopted by a court.

A synthetic mucoadhesive polymer, such as a carbomer or polyacrylic acid derivative, could avoid claims limited to natural milk proteins. It may not avoid claim 1 or claim 5 if it is a bioadhesive polymer present in the required range.

Hypromellose

Hypromellose, also known as hydroxypropyl methylcellulose, is the specified sustained-release polymer in claim 16 and the related dependent claims. Other sustained-release polymers may avoid claims 16 through 20 but remain relevant to claim 1 and claims 5 through 6.

What is the strongest claim against an acyclovir buccal tablet?

Claim 17 is the most direct narrow claim for an acyclovir product with the specified excipient system:

A formulation satisfying claim 1.
Sodium lauryl sulfate.
Natural milk proteins or mixtures.
Hypromellose.
Acyclovir.

Claims 19 and 20 are also commercially significant because they specify 50 mg or 100 mg acyclovir and retain the core excipient architecture.

Claim	Commercial relevance	Main vulnerability
1	Broadest formulation claim	Requires proof of primary-granule architecture
3	Separates bioadhesive polymer from primary granules	Requires evidence of polymer location
16	Specific sodium lauryl sulfate, milk protein, hypromellose formulation	Narrow ingredient and concentration limitations
17	Claim 16 plus acyclovir	Strong product-specific coverage
19	50 mg or 100 mg acyclovir formulation	Dose and composition limitations
20	Claim 19 plus polyvinylpyrrolidone	Narrowest commercial formulation claim
24	Manufacturing sequence	Avoidable through a different process
28	Treatment using claim 1 formulation	Depends on product and oral-mucosal use

When does US Patent 8,791,127 lose exclusivity?

US Patent 8,791,127 was granted on July 29, 2014. The ordinary patent term is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, patent-term extension, terminal disclaimers, and applicable transitional rules under 35 U.S.C. § 154.

The supplied claims do not establish the effective filing date, patent-term adjustment, terminal disclaimer status, or any patent-term extension. The patent should therefore be analyzed as a formulation patent with an expected term in the late 2020s, rather than assigned an unsupported exact expiration date.

A patent expiration date also does not determine FDA market exclusivity. FDA regulatory exclusivity, listed patent status, and patent enforceability are separate questions.

What is the Orange Book status of US Patent 8,791,127?

Orange Book listing cannot be determined from the claim text alone. The relevant regulatory analysis must distinguish:

Whether the patent is listed for an approved acyclovir product.
Whether the listed claims cover the approved drug substance, drug product, or method of use.
Whether the patent has been delisted, expired, or removed.
Whether an abbreviated new drug application has made a Paragraph IV certification.

For a formulation such as an acyclovir buccal tablet, the strongest potential listing theory would be a drug-product claim covering the dosage form and its composition. A process claim generally has weaker Orange Book relevance unless it falls within the statutory listing categories for the approved product.

FDA’s Orange Book identifies patents and regulatory exclusivity associated with approved drug products, but it does not decide infringement or validity. Patent scope remains governed by the issued claims and judicial claim construction (FDA, 2024; 21 C.F.R. § 314.53).

Are there Paragraph IV challenges or generic entry risks?

A generic applicant seeking approval for an acyclovir buccal tablet would likely evaluate four launch routes:

Route	Regulatory position	Patent exposure
Wait for patent expiration	Paragraph III certification	Delayed entry
Challenge listed patent validity	Paragraph IV certification	Litigation and possible 30-month stay
Design around formulation	No infringement position for relevant claims	Requires different excipient structure or process
Seek licensing or settlement	Commercial resolution	Terms may restrict launch timing

A conventional oral acyclovir tablet or capsule is unlikely to infringe these claims because it normally lacks oral-mucosal adhesion, prolonged local release, and the required primary-granule structure. A generic buccal tablet is materially higher risk.

The main design-around options are:

Use a different antiviral, such as famciclovir, where clinically appropriate.
Use a different dosage form, such as a conventional tablet, capsule, cream, or systemic product.
Replace sodium lauryl sulfate with another surfactant.
Remove or replace natural milk proteins.
Use a different sustained-release polymer.
Incorporate the bioadhesive polymer into the primary granules.
Avoid the claimed granulation sequence.
Use a noncompressed film, gel, patch, or liquid system.

Some design-arounds may avoid claims 16 through 20 while leaving claim 1 in dispute. The broad claim is therefore the main residual risk after a formulation redesign.

What patent landscape surrounds this technology?

The relevant landscape has four clusters.

Acyclovir and antiviral formulation patents

Acyclovir has extensive prior art covering oral, topical, ophthalmic, injectable, and controlled-release formulations. The active ingredient itself is long established. The defensible value of US 8,791,127 lies in dosage-form engineering, not acyclovir composition-of-matter protection.

Buccal and mucoadhesive delivery patents

Earlier buccal-delivery patents commonly claim:

Adhesive polymers.
Oral mucosal residence.
Controlled release.
Films, tablets, gels, and patches.
Local delivery of antiviral or analgesic agents.

US 8,791,127 differentiates its architecture through the combination of primary granules and separately dispersed bioadhesive and sustained-release polymers.

Milk-protein excipient patents

Natural milk proteins create a narrower technical cluster. Patentability and validity analysis should examine whether prior art disclosed casein, whey, or milk-protein mixtures as oral bioadhesive excipients in combination with antiviral agents and release-control polymers.

Manufacturing-process patents

The granulate-blend-compress sequence may be useful as an enforcement backstop, particularly where a competitor’s final tablet is analytically similar to the patented formulation. It is less robust against a competitor that changes the manufacturing sequence while retaining similar final ingredients.

How strong is the patent estate?

The patent is strongest against a directly copied acyclovir buccal tablet with the following profile:

50 mg or 100 mg acyclovir.
Sodium lauryl sulfate at approximately 2% to 6%.
Natural milk proteins at 10% to 40%.
Hypromellose at 10% to 40%.
Polyvinylpyrrolidone as binding agent.
Separate antiviral-containing primary granules.
Bioadhesive polymer added after granulation.
Compression into a buccal tablet.

Its strength is lower against:

Non-tablet dosage forms.
Formulations without natural milk proteins.
Formulations without sodium lauryl sulfate.
Products using a different granulation architecture.
Systemic acyclovir or valacyclovir products.
Products with no oral-mucosal administration.

The claim set has substantial internal fallback protection. If claim 1 is narrowed or found vulnerable, claims 16 through 20 may preserve protection for a specific commercial product. Conversely, the narrower claims are more vulnerable to an ingredient substitution or process change.

What licensing and litigation issues matter?

The commercial value of the patent depends on the approved product associated with the formulation and on whether the patent is listed against that product. A licensee would focus on:

Patent ownership and chain of title.
Any continuation, divisional, or foreign counterpart rights.
Patent-term adjustment and terminal disclaimers.
FDA Orange Book listing.
Paragraph IV certifications.
Prior litigation involving the patent family.
Settlement restrictions on generic entry.
Territory, field-of-use, and sublicense rights.
Product-by-process and manufacturing-control obligations.

No litigation, settlement, licensing deal, or Paragraph IV event is established by the claim text supplied. Those events are external legal and regulatory records and should not be inferred from the issued claims.

Key Takeaways

US Patent 8,791,127 is a formulation and manufacturing patent, not an acyclovir composition-of-matter patent.
Claim 1 requires a specific multipart formulation architecture, including antiviral-containing primary granules.
Claims 16 through 20 provide the most commercially relevant protection for an acyclovir buccal tablet.
Sodium lauryl sulfate, natural milk proteins, hypromellose, and the separation of the bioadhesive polymer from the primary granules are central limitations.
Claim 24 protects the granulation, blending, and compression sequence.
Conventional oral, topical, or systemic acyclovir products are outside the apparent core scope unless they also satisfy the mucoadhesive and granulation limitations.
A generic buccal tablet using the same excipient system presents materially greater infringement risk than a conventional acyclovir product.
Exact expiration, Orange Book listing, Paragraph IV activity, litigation, and settlement status cannot be derived from the supplied claims.

FAQs

Does US Patent 8,791,127 cover valacyclovir?

Not directly based on the supplied claims. The patent requires an antiviral agent, but the commercially specific dependent claims identify acyclovir. A valacyclovir product would still require analysis under claim 1 and the remaining structural limitations.

Can a formulation avoid the patent by removing sodium lauryl sulfate?

Removing sodium lauryl sulfate may avoid claims directed to sodium lauryl sulfate, including claim 16 and related claims. It may not avoid claim 1 if another alkali metal alkyl sulfate is used and all other limitations remain satisfied.

Does claim 24 cover every method of making the tablet?

No. Claim 24 requires granulation of the antiviral core ingredients, subsequent blending with bioadhesive and sustained-release polymers, and compression. A materially different manufacturing sequence may avoid claim 24 while still producing a product potentially covered by composition claims.

Are natural milk proteins limited to casein?

The supplied claims do not define the term by naming only casein. The scope may include other natural milk proteins or mixtures, subject to claim construction and the specification’s disclosures.

Is a 50 mg acyclovir buccal tablet automatically infringing?

No. Dose alone is insufficient. The product must also satisfy the relevant formulation, ingredient, polymer, granulation, and oral-mucosal limitations.

References

United States Patent No. 8,791,127. (2014). Claims 1-30.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. FDA.
U.S. Food and Drug Administration. (2024). 21 C.F.R. § 314.53: Submission of patent information. FDA.
United States Code. (2024). 35 U.S.C. § 154: Contents and term of patent; provisional rights.
United States Code. (2024). 21 U.S.C. § 355(j): Abbreviated applications and patent certifications.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Ligand Pharms	SITAVIG	acyclovir	TABLET;BUCCAL	203791-001	Apr 12, 2013		DISCN	Yes	No	8,791,127	⤷ Start Trial	Y			TREATMENT OF HERPES LABIALIS	⤷ 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

Foriegn Application Priority Data
Foreign Country	Foreign Patent Number	Foreign Patent Date
	06290480	Mar 24, 2006

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	060085	⤷ Start Trial
Austria	E446743	⤷ Start Trial
Australia	2007231029	⤷ Start Trial
Brazil	PI0709057	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,791,127

Which drugs does patent 8,791,127 protect, and when does it expire?

Summary for Patent: 8,791,127