US Patent 8,747,896: Scope, Claims, Expiration, Orange Book Status and Patent Landscape

US Patent 8,747,896 protects prolonged-release, mucoadhesive oral formulations containing selected antiviral agents, with particular emphasis on acyclovir buccal delivery. The broadest claim requires a specific combination of antiviral, diluent, alkali metal alkyl sulfate, binding agent, bioadhesive polymer, sustained-release polymer, granule architecture and oral-mucosal release profile. The patent is associated with BioAlliance Pharma’s acyclovir buccal product, Sitavig.

The patent’s principal commercial value is narrower than the full Markush language suggests. The strongest practical coverage is directed to 50 mg or 100 mg acyclovir formulations using sodium lauryl sulfate, microcrystalline cellulose, polyvinylpyrrolidone, hypromellose and milk-protein-based bioadhesive material.

What does US Patent 8,747,896 protect?

US 8,747,896 protects a formulation rather than acyclovir as an active ingredient. The claims require a drug-delivery system that adheres to the oral mucosa and releases antiviral drug for an extended period.

The core elements of independent claim 1 are:

Claim element	Required scope
Antiviral agent	Acyclovir, valacyclovir, ganciclovir or zidovudine
Diluent	Present, but not limited to a named material in claim 1
Alkali metal alkyl sulfate	Present; sodium lauryl sulfate is the key commercial example
Binding agent	Present
Bioadhesive polymer	Must permit adhesion to oral mucosa
Sustained-release polymer	Must be present
Release period	From 30 minutes to at least 15 hours
Granule structure	Primary granules contain antiviral, diluent, alkali metal alkyl sulfate and binding agent
Polymer location	Bioadhesive polymer is dispersed in the formulation

The claim does not require every formulation to use acyclovir. It reaches three additional antiviral categories. A competitor using valacyclovir, ganciclovir or zidovudine could therefore fall within claim 1 if the remaining formulation and release limitations are met.

The patent does not claim every oral mucoadhesive antiviral product. A product that lacks the required alkali metal alkyl sulfate, does not contain the specified primary granules, uses no sustained-release polymer or fails the release limitation may avoid literal infringement of claim 1.

How do the independent claims divide the patent estate?

The patent has two principal independent claim types.

Claim 1: formulation claim

Claim 1 is the principal composition claim. It combines chemical ingredients with physical-structural and performance limitations. This makes it broader than a formulation claim limited only to percentages, but narrower than a simple claim to an antiviral-containing buccal tablet.

A potential infringement analysis would require testing or documentary evidence regarding:

The identity of the antiviral agent.
The presence and concentration of an alkali metal alkyl sulfate.
The granulation process and composition of the primary granules.
The presence and location of the bioadhesive polymer.
The sustained-release polymer.
Oral adhesion and release performance.

The granule limitation is commercially important. A generic manufacturer may avoid infringement by placing the bioadhesive polymer inside the primary granules, although claims 3 and 4 expressly address formulations in which the bioadhesive polymer is not in those granules.

Claim 15: method-of-treatment claim

Claim 15 covers treating a mucosal disease by administering a formulation of claim 1 or claim 2 to the oral mucosa.

The method claims add potential enforcement value where a competitor’s product label instructs oral-mucosal administration for a mucosal disease. They are less useful where the accused product is sold without an oral-mucosal indication or where administration occurs by a different route.

Claims 27 and 28 separately target administration of formulations within the scope of claims 5 and 10. Claim 28 is directed specifically to acyclovir.

Which dependent claims provide the strongest commercial coverage?

The most commercially relevant dependent claims are claims 10 through 14 and claims 24 through 26.

Claims	Subject matter	Commercial relevance
2	No more than 5% polyvinylpyrrolidone	Captures low-PVP formulations
3-4	Bioadhesive polymer absent from primary granules	Addresses granule architecture
5	2%-6% alkali metal alkyl sulfate	Targets sodium lauryl sulfate range
6	0.5%-5% binding agent	Adds concentration limitation
7	0.5%-5% polyvinylpyrrolidone	Covers a specific PVP range
8-9	Natural proteins, including milk proteins	Important for milk-protein systems
10-12	Acyclovir, at least 20-hour delivery, 50-100 mg	Core Sitavig-type coverage
13	Detailed acyclovir formulation ranges	Strong formulation-specific claim
14	Salivary acyclovir above 22.5 ng/mL for 36 hours	Performance-based product claim
16-19	Starch-free and sub-125-micron granules	Manufacturing and particle-size limitations
20-23	10%-40% bioadhesive polymer, including milk proteins	Broadens protein-polymer coverage
24-26	Specific ingredient and percentage combinations	Narrow but potentially strong formulation claims

Claims 10, 11, 12 and 14 are particularly relevant to an acyclovir buccal tablet. Claim 14 may be difficult to evaluate from public product information because it depends on salivary concentration data, testing conditions and sampling methodology.

What formulation is described in claims 24 through 26?

Claims 24 and 26 identify highly specific formulations:

Component	Claimed amount
Microcrystalline cellulose	15%
Sodium lauryl sulfate	4.5%
Polyvinylpyrrolidone	0.4%
Bioadhesive polymer or milk protein concentrate	20%
Hypromellose	15%
Magnesium stearate	1%
Colloidal silica	0.4%
Acyclovir	50 mg or 100 mg

Claim 24 permits the bioadhesive component to be milk protein concentrate, pea protein, Carbopol 974 or chitosan. Claim 25 narrows claim 24 to milk protein concentrate. Claim 26 is directed to the 100 mg acyclovir version with milk protein concentrate.

These claims have a narrower literal scope than claim 1 but may be harder to design around if a competing product uses substantially the same excipient system. The 0.4% PVP concentration in claims 24 and 26 is distinct from claim 13’s 0.5%-5% PVP range.

When does US Patent 8,747,896 lose exclusivity?

The patent was granted on June 10, 2014. Public patent records identify a November 20, 2007 U.S. filing and an earlier November 20, 2006 priority date. On that record, the ordinary patent term is expected to run through November 20, 2027, subject to any patent-term adjustment, terminal disclaimer or applicable regulatory extension recorded by the USPTO or FDA.[1][2]

Milestone	Date
Earliest reported priority	November 20, 2006
U.S. filing	November 20, 2007
Grant	June 10, 2014
Expected ordinary expiration	November 20, 2027

Patent expiration does not itself establish immediate generic availability. FDA regulatory exclusivity, other patents, product-specific labeling restrictions and litigation settlements can alter the practical launch date.

What is the Orange Book status of US 8,747,896?

The patent is associated with Sitavig, an acyclovir buccal tablet approved by FDA under NDA 208? The relevant FDA product is a 50 mg buccal tablet indicated for treatment of recurrent herpes labialis in immunocompetent adults.[3]

The Orange Book analysis should distinguish between:

FDA-listed patents for the reference drug;
patents that claim the active ingredient;
formulation patents;
method-of-use patents; and
patents that may be relevant commercially but are not listed in the Orange Book.

For Sitavig, the relevant listed patent protection is formulation- and delivery-based rather than a basic acyclovir compound patent. Acyclovir has long been available in conventional oral, topical and injectable dosage forms. The differentiator is the oral-mucosal delivery platform.

The exact current Orange Book listing, delisting status and pediatric exclusivity status must be determined from the FDA’s current patent listing database and the most recent approved labeling. Patent records alone do not establish current Orange Book status.

Which companies are challenging US 8,747,896?

No Paragraph IV challenger, federal patent case, or settlement agreement can be established from the claim text alone. A complete current challenge analysis requires live review of FDA Paragraph IV notices, district-court dockets, ANDA litigation records and Orange Book updates.

The commercial challenger set is likely to include manufacturers of:

generic acyclovir tablets;
generic valacyclovir tablets;
alternative buccal or sublingual antiviral products; and
compounded or locally delivered acyclovir formulations.

Conventional generic acyclovir tablets would not automatically infringe this patent because they may lack oral-mucosal adhesion, sustained release, the required granule structure and the sodium-lauryl-sulfate formulation architecture.

What generic launch risks exist?

Conventional oral acyclovir generics

The risk is moderate to low for conventional swallowed tablets if they do not reproduce the claimed mucoadhesive architecture. The risk increases if the product is labeled for placement against the oral mucosa or uses the claimed excipient and granule design.

Generic Sitavig-type products

The risk is materially higher. A generic acyclovir buccal tablet would likely need to address:

Claim 1’s multi-component formulation limitations.
Claims 10-14’s acyclovir-specific limitations.
Claims 24-26’s detailed composition.
The salivary-concentration limitation in claim 14.
Method claims tied to oral-mucosal treatment.

A Paragraph IV certification could challenge validity, enforceability or infringement. The principal validity theories would likely involve obviousness over prior mucoadhesive tablets, sustained-release oral systems and acyclovir formulations.

Valacyclovir and other antiviral products

Claim 1 expressly reaches valacyclovir, ganciclovir and zidovudine. The absence of an acyclovir limitation does not remove risk if the accused formulation satisfies the structural and performance requirements. Claims 10-14 and 24-26, however, are acyclovir-specific and would not apply to those products.

How strong is the patent estate?

The patent is strongest against a product that copies the commercial formulation and delivery profile. Its strength is lower against products that use a different manufacturing process, polymer system or dosage form.

Patent feature	Strength assessment
Acyclovir buccal delivery	Strong commercial relevance
Broad antiviral Markush group	Broad but vulnerable to prior-art and enablement arguments
Sodium lauryl sulfate limitation	Useful composition discriminator
Primary-granule architecture	Potentially strong if process evidence is available
Milk-protein bioadhesion	Stronger in narrow claims 8, 9 and 22-26
20-hour or 36-hour release claims	Useful but fact-intensive
50 mg and 100 mg dosage strengths	Directly relevant to commercial products
Method claims	Dependent on labeling and actual administration
Manufacturing limitations	Potentially difficult to detect externally

The combination of composition, granulation and performance limitations gives the patent several infringement theories. It also creates validity pressure because the claims aggregate many known pharmaceutical technologies: binders, diluents, surfactants, mucoadhesive polymers and hypromellose-based sustained release.

What manufacturing and intellectual-property barriers affect design-around strategies?

A design-around product could target one or more required claim limitations:

Replace sodium lauryl sulfate with a non-alkali-metal surfactant.
Use a different granule architecture.
Put the bioadhesive polymer into, rather than outside, the primary granules.
Replace milk protein with a synthetic or polysaccharide bioadhesive.
Use a non-hypromellose release-control system.
Develop a sublingual, topical or conventional oral dosage form.
Use a release duration outside the claimed range, if clinically acceptable.
Avoid the claimed acyclovir concentration or salivary exposure profile.

Each change may create separate formulation-development risks. A substitute polymer must still deliver adequate adhesion, residence time, drug release and patient tolerability. A different surfactant may alter granulation, dissolution or mucosal irritation. A different dosage route may require a new FDA regulatory strategy.

How does US 8,747,896 compare with conventional acyclovir patents?

Product type	Main protection	Exposure under US 8,747,896
Conventional oral acyclovir tablet	Active ingredient and conventional formulation patents largely expired or weak	Usually limited
Valacyclovir tablet	Different prodrug and conventional oral dosage form	Claim 1 exposure only if mucoadhesive architecture is copied
Sitavig-type buccal tablet	Mucoadhesion, sustained release and oral-mucosal delivery	Highest exposure
Topical acyclovir cream	Topical formulation and use	Generally outside the claimed oral-mucosal scope
Compounded oral adhesive preparation	Depends on composition and administration instructions	Fact-specific
Novel antiviral buccal tablet	Delivery-platform patents and antiviral-specific claims	Potential claim 1 exposure

What litigation and settlement issues should be monitored?

The key monitoring points are:

FDA Orange Book additions, removals and patent-expiration updates.
Paragraph IV notices concerning Sitavig or an equivalent acyclovir buccal product.
ANDA litigation under the Hatch-Waxman Act.
Any patent-term adjustment or extension recorded for US 8,747,896.
License, assignment or commercialization agreements involving BioAlliance Pharma, Onxeo or Sitavig rights.
Continuation or divisional patents covering the same formulation platform.
Foreign family patents in Europe, Canada and other markets.

Patent-family coverage should be reviewed separately by jurisdiction. A U.S. expiration date does not determine the status of corresponding European, Canadian, Australian or Asian patents.

Key Takeaways

US 8,747,896 is a formulation and delivery patent, not a basic acyclovir patent.
Claim 1 covers selected antiviral agents in a prolonged-release oral-mucoadhesive system.
The key structural limitations are primary granules containing the antiviral, diluent, alkali metal alkyl sulfate and binding agent, with bioadhesive polymer dispersed in the formulation.
Claims 10-14 and 24-26 provide the most important acyclovir and Sitavig-related coverage.
The commercial formulation is centered on acyclovir, sodium lauryl sulfate, microcrystalline cellulose, PVP, hypromellose and milk-protein-based adhesion.
The expected ordinary expiration is November 20, 2027, based on the reported U.S. filing and priority chronology.
Conventional oral acyclovir generics present less risk than a Sitavig-type buccal product.
The principal design-around routes involve changing the surfactant, granule structure, bioadhesive polymer, release-control polymer or administration route.
Current Paragraph IV, Orange Book and settlement status cannot be inferred from the claim text or patent grant alone.

FAQs

Does US 8,747,896 cover ordinary acyclovir tablets?

Generally, no. Ordinary swallowed acyclovir tablets may not contain the required oral-mucoadhesive system, sustained-release polymer, primary-granule structure or oral-mucosal release profile.

Does the patent cover valacyclovir buccal formulations?

Potentially. Claim 1 expressly includes valacyclovir, but the formulation must satisfy all other claim limitations. A valacyclovir product would not be covered by acyclovir-specific claims such as claims 10-14 and 24-26.

Is milk protein required for infringement?

No. Milk protein is required only by narrower claims. Claim 1 permits at least one bioadhesive polymer without limiting the polymer to milk protein.

Can a product avoid the patent by using a different antiviral?

Not necessarily. Claim 1 covers four antiviral agents. Switching from acyclovir to valacyclovir, ganciclovir or zidovudine may avoid acyclovir-specific claims but may remain within claim 1.

Does patent expiration permit an immediate generic Sitavig launch?

No. A launch also depends on FDA approval, Orange Book certification, any other unexpired patents, litigation, settlement terms and regulatory exclusivity.

References

United States Patent and Trademark Office. (2014). U.S. Patent No. 8,747,896, prolonged release mucoadhesive formulations. https://patents.google.com/patent/US8747896
United States Patent and Trademark Office. (n.d.). Patent Center. https://patentcenter.uspto.gov/
U.S. Food and Drug Administration. (n.d.). Sitavig prescribing information and Drugs@FDA. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (n.d.). 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

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	⤷ Start Trial	⤷ 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
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,747,896

Which drugs does patent 8,747,896 protect, and when does it expire?

Summary for Patent: 8,747,896