US Patent 8,859,623: Claim Scope, Patent Strength, and R-Phenylephrine Ophthalmic Patent Landscape

US Patent No. 8,859,623 protects a narrow method of using refrigerated ophthalmic R-phenylephrine hydrochloride for pupil dilation. The claims require a specific stereochemical purity, an aqueous buffer, six-month chiral-stability performance, cold storage, ophthalmic administration, and, in dependent claims, specified concentrations, containers, labeling, and opacity.

The patent does not broadly claim phenylephrine, pupil dilation, or every R-phenylephrine formulation. Its practical value depends on whether a competing product uses R-phenylephrine hydrochloride, meets the claimed chiral-purity and stability thresholds, and is stored and administered within the specified conditions.

What does US Patent 8,859,623 cover?

The independent claim covers a method with the following required elements:

Claim element	Requirement
Active ingredient	R-phenylephrine hydrochloride
Initial chiral purity	At least 95%
Vehicle	Aqueous buffer
Stability	At least 95% of the initial chiral purity after six months
Administration	Into an eye of an individual requiring pupil dilation
Storage before administration	Between -10°C and 10°C
Purity at administration	At least 95% chiral purity

The patent therefore combines composition characteristics, storage conditions, stability data, and a therapeutic use. A product that satisfies only the formulation limitations but is not administered for pupil dilation would not fall within claim 1 as written.

The claims are method claims rather than broad composition claims. That distinction limits enforcement against manufacturers whose product is chemically similar but whose labeled or actual use does not satisfy the claimed administration and storage conditions.

How narrow is claim 1 of US Patent 8,859,623?

Claim 1 is narrow because infringement requires satisfaction of every limitation. The most consequential limitations are:

The active ingredient must be the R enantiomer of phenylephrine hydrochloride.
The initial chiral purity must be at least 95%.
The formulation must contain an aqueous buffer.
The formulation must retain at least 95% of its initial chiral purity after six months.
The product must have been stored between -10°C and 10°C before administration.
The composition must be administered into an eye for pupil dilation.

The claim does not expressly require a particular pH, buffer species, bottle material, dosage volume, or concentration. Those features appear in dependent claims or are absent from the claims.

A competing product containing racemic phenylephrine would generally fall outside the literal scope of the R-phenylephrine limitation. A competing product containing R-phenylephrine but lacking an aqueous buffer could avoid literal infringement of claim 1. A product stored above 10°C before use could also avoid the express storage limitation, subject to the factual record and any doctrine-of-equivalents analysis.

What do claims 2 through 13 add?

The dependent claims create narrower positions around refrigeration, purity, concentration, packaging, labeling, container size, and opacity.

Claim	Added limitation
2	Storage between 2°C and 8°C
3	Initial chiral purity of at least 99%
4	Initial chiral purity of at least 99.3%
5	Retains at least 97% of initial chiral purity after six months
6	Retains at least 99% of initial chiral purity after six months
7	Retains at least 99.5% of initial chiral purity after six months
8	Contains 2.5% w/v or 10% w/v R-phenylephrine hydrochloride
9	Packaged in a 1-15 mL plastic or glass bottle
10	Package identifies storage between -10°C and 10°C
11	Package identifies storage between 2°C and 8°C
12	Bottle size of approximately 2, 3, 5, 10, or 15 mL
13	Bottle is opaque

Claims 2, 10, and 11 are especially relevant to commercial products distributed under refrigerated labeling. Claims 8 and 12 target conventional ophthalmic strengths and package formats. Claim 13 is a packaging limitation that may be difficult to enforce unless the product’s container is demonstrably opaque.

What is the technical subject matter of the patent?

The technical focus is preservation of the R enantiomer of phenylephrine in an aqueous ophthalmic product during storage. The claims treat chiral purity as a product-quality attribute that may decline over time through racemization or other stereochemical degradation.

The patent is not directed primarily to improving mydriatic pharmacology. It is directed to maintaining the desired enantiomeric composition through storage and administration.

The claimed stability relationship is relative, not merely absolute. For example:

A formulation beginning at 99.3% chiral purity and retaining 95% of that initial value would need to remain at approximately 94.335% chiral purity.
A formulation beginning at 99.3% and retaining 99% of its initial value would need to remain at approximately 98.307%.
A formulation beginning at 99.3% and retaining 99.5% would need to remain at approximately 98.8035%.

Claims 5 through 7 impose progressively more demanding retention thresholds, but they depend on claim 1 and therefore retain all of its storage, buffering, administration, and pupil-dilation requirements.

How could a generic or competing product avoid infringement?

A competitor could design around the patent through several routes:

Use racemic phenylephrine

A racemic formulation containing both R- and S-phenylephrine would not satisfy the claim limitation requiring R-phenylephrine hydrochloride having the specified chiral purity, assuming the product is not predominantly or exclusively the claimed enantiomer.

Use a nonaqueous or nonbuffered formulation

Claim 1 requires an aqueous buffer. A formulation using a different vehicle or a formulation that is aqueous but not buffered could present a noninfringement position, depending on the precise formulation and claim construction.

Use nonrefrigerated storage

The claimed method requires storage between -10°C and 10°C before administration. A product labeled and maintained at controlled room temperature may avoid the literal storage limitation. This strategy is commercially attractive because refrigeration can increase distribution costs and complicate ambulatory or office-based ophthalmic use.

Use a different indication or administration protocol

The claims require administration into an eye of an individual in need of pupil dilation. A product labeled only for another ophthalmic purpose could avoid the method-of-use claim, although actual use, prescribing information, marketing, and induced-infringement evidence would remain relevant.

Use a formulation outside the claimed purity and stability parameters

A product with less than 95% initial chiral purity, or one that does not retain the claimed percentage after six months, may avoid the claims. This route must be assessed carefully because analytical methods, sampling points, specifications, and batch records could determine whether the product meets the limitations.

What formulations are protected by US Patent 8,859,623?

The patent potentially covers refrigerated buffered ophthalmic formulations containing high-purity R-phenylephrine hydrochloride. Claim 8 specifically identifies 2.5% w/v and 10% w/v concentrations.

Formulation characteristic	Relevance
2.5% w/v R-phenylephrine hydrochloride	Expressly covered by claim 8 if all claim 1 limitations are met
10% w/v R-phenylephrine hydrochloride	Expressly covered by claim 8 if all claim 1 limitations are met
Other concentration	May fall under claim 1 if the other limitations are satisfied
Aqueous buffered formulation	Required by claim 1
Refrigerated storage	Required by claim 1
2°C to 8°C storage	Narrower claim 2 position
Plastic or glass bottle	Claims 9 and 12
Opaque bottle	Claim 13
Labeled refrigerated storage	Claims 10 and 11

The claims do not limit the buffer to a particular chemical species. They also do not require a particular preservative, tonicity agent, surfactant, viscosity modifier, or antioxidant.

How strong is the patent estate?

The patent’s claim strength is mixed.

Strengths

The claims combine several measurable limitations. A product meeting the stereochemical, stability, storage, and use requirements could be identifiable through:

Certificate-of-analysis records
Chiral chromatography
Stability protocols
Product labeling
Distribution records
Container specifications
FDA-approved labeling
Marketing materials and prescribing information

The six-month chiral-stability limitation may be commercially significant because a competitor cannot necessarily avoid the claim merely by matching the initial purity. It must also address the specified retention performance if it uses the claimed storage and administration model.

The claims also cover both broad refrigeration from -10°C to 10°C and the commercially conventional 2°C to 8°C range.

Weaknesses

The independent claim contains multiple design-around points. The need to prove the exact storage condition and chiral-purity relationship can create substantial enforcement complexity. A product may be manufactured at high purity but marketed with different storage instructions. Alternatively, a product may meet the stability requirement under some conditions but not the claimed six-month condition under the relevant evidence.

The patent also lacks a broad composition claim in the provided claim set. That limits direct action against manufacturing or sale of a formulation absent proof that the product is used, marketed, or intended to be used in the claimed method.

Packaging claims 9 through 13 are narrower and generally weaker than the core formulation and use limitations. Bottle size, opacity, and label language may change without affecting the therapeutic product.

When does US Patent 8,859,623 lose exclusivity?

The patent’s enforceable term depends on its earliest effective nonprovisional filing date, any terminal disclaimer, patent-term adjustment, and other USPTO term data. The patent number and claim text alone do not establish a reliable expiration date.

For a US utility patent, the ordinary term is generally 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment and statutory limitations.[1] A complete term analysis must also account for:

Continuation or divisional priority
Patent-term adjustment
Terminal disclaimers
Patent-term extension
Reexamination or post-grant proceedings
Disclaimer or lapse events

Because this patent claims an old active pharmaceutical ingredient but a specialized stereochemical formulation and storage method, its commercial exclusivity would depend more on the enforceable claim term and market adoption than on the age of phenylephrine itself.

What is the Orange Book status of US Patent 8,859,623?

The Orange Book does not list patents merely because they exist. A patent generally becomes relevant to Orange Book litigation only if it is submitted by the applicable NDA holder and qualifies under FDA listing rules.[2]

The provided claims are method claims directed to pupil dilation. They could be candidates for listing if tied to an approved drug product and if the patent satisfies the applicable FDA listing requirements. The claim text alone does not establish that US 8,859,623 is currently listed in the Orange Book, associated with a particular NDA, or eligible for a Paragraph IV notice.

A regulatory review should distinguish among:

Status	Legal significance
Patent exists but is not listed	No Orange Book Paragraph IV certification based solely on that patent
Patent listed for an NDA	ANDA applicant may need a certification
Method-of-use patent listed with a use code	Applicant may use a section viii statement if the labeling omits the patented use
Patent listed for a formulation or product	Greater risk of a direct Paragraph IV dispute
Patent expired or disclaimed	Reduced or eliminated Orange Book barrier, subject to other listed patents

What Paragraph IV challenges could target this patent?

An ANDA applicant could challenge a listed patent through a Paragraph IV certification asserting that the patent is invalid, unenforceable, or will not be infringed.[3]

Potential validity theories would likely focus on:

Anticipation

A challenger could search for prior art disclosing:

R-phenylephrine hydrochloride in an ophthalmic formulation
At least 95% chiral purity
Buffered aqueous compositions
Refrigerated storage
Six-month stereochemical stability
Pupil-dilation use

Because the claim combines several limitations, a single reference would need to disclose the claimed combination for anticipation.

Obviousness

Obviousness could be based on combining prior art concerning:

Resolution or enrichment of phenylephrine enantiomers
Conventional phenylephrine ophthalmic solutions
Refrigerated storage
Buffer selection
Stability testing
Standard ophthalmic packaging

The key question would be whether a skilled person would have had a reasonable expectation that the claimed high-purity R enantiomer would retain the specified level of chiral purity under the claimed conditions.

Written description and enablement

The challenger could examine whether the specification supports the full breadth of:

All aqueous buffers
All concentrations within the claims
All plastic and glass bottles
All storage temperatures from -10°C to 10°C
All products retaining the specified chiral-purity percentages

A narrow experimental disclosure supporting only selected buffers or concentrations could create written-description or enablement arguments against broader claim language.

Indefiniteness

Potential disputes could involve:

The meaning of "initial chiral purity"
The analytical method used to measure chiral purity
The meaning of "at least 95% of the initial chiral purity"
The evidentiary meaning of "about" in container sizes
Whether storage "between -10 to 10 degree Celsius" refers to continuous storage, average temperature, or allowable excursions

The strength of such arguments would depend on the patent specification, prosecution history, and analytical definitions.

What litigation or settlement risk exists?

The claim structure supports a targeted ANDA dispute rather than a broad product-market dispute. Litigation risk would increase if:

The branded product is approved with refrigerated storage;
The label identifies 2.5% or 10% R-phenylephrine hydrochloride;
The product uses high enantiomeric purity;
The patent is listed against the relevant NDA;
The generic’s proposed label includes pupil dilation;
The generic uses an aqueous buffered formulation.

Risk would decrease if the generic:

Uses racemic phenylephrine;
Omits the patented pupil-dilation use where permitted;
Uses room-temperature storage;
Uses a nonbuffered formulation;
Uses a different active ingredient or delivery system;
Demonstrates a different chiral-stability profile.

No litigation, Paragraph IV filing, or settlement agreement can be attributed to this patent from the claim text alone. Settlement terms, if any, would require review of PACER, FDA records, ANDA litigation notices, SEC filings, and the patent’s prosecution and assignment histories.

How does this patent compare with competing phenylephrine patent strategies?

Patent strategy	Typical scope	Relevance to US 8,859,623
Active-ingredient patent	Claims phenylephrine or an enantiomer	US 8,859,623 does not broadly claim phenylephrine itself
Composition patent	Claims ingredients, concentrations, pH, or excipients	This patent has formulation limitations but uses them in a method claim
Stability patent	Claims storage or degradation control	Chiral stability is central to the patent
Method-of-use patent	Claims treatment or administration	The patent requires ophthalmic administration for pupil dilation
Packaging patent	Claims container or labeling	Claims 9 through 13 provide narrow packaging coverage
Device patent	Claims dispenser or delivery system	No device limitation appears in the provided claims
Manufacturing patent	Claims synthesis, resolution, or purification	No manufacturing process is claimed in the provided claims

The patent is best characterized as a stereochemical stability and refrigerated-use patent. It is not a complete blocking estate for all phenylephrine ophthalmic products.

What manufacturing and intellectual-property barriers matter?

The principal technical barrier is production of R-phenylephrine hydrochloride at consistently high chiral purity. A manufacturer must control:

Enantiomeric resolution or asymmetric synthesis
Residual S-phenylephrine
Crystallization and salt formation
pH and buffer composition
Long-term stereochemical stability
Container interaction and light exposure
Cold-chain handling
Analytical validation

The principal patent barrier is not merely production of high-purity R-phenylephrine. It is the combination of high purity, refrigerated storage, six-month retention, and ophthalmic pupil-dilation use.

A manufacturer that controls the active ingredient but uses room-temperature storage or a nonbuffered product may reduce exposure to this patent while remaining vulnerable to other formulation, use, process, or regulatory patents.

What is the likely commercial impact?

The commercial impact depends on whether R-phenylephrine is used as a differentiated product rather than as a conventional racemic generic. A successful R-enantiomer product could seek advantages based on purity, stability, tolerability, dosing, or regulatory positioning. The patent would be most valuable if it covers the commercial product’s actual label and supply chain.

The patent is less valuable against the broad existing market for phenylephrine ophthalmic products because those products may use racemic phenylephrine and may not meet the R-enantiomer limitation.

Potential revenue exposure should therefore be assessed at the product level:

Product characteristic	Exposure to US 8,859,623
Racemic phenylephrine	Generally low
High-purity R-phenylephrine	Potentially high
Refrigerated buffered formulation	High if used for pupil dilation
Room-temperature formulation	Reduced literal exposure
2.5% or 10% R-phenylephrine	Increased exposure under claim 8
Opaque bottle with claimed size	Increased exposure under claims 9-13
Product without pupil-dilation labeling	Reduced method-of-use exposure

Key Takeaways

US 8,859,623 is a narrow method patent covering refrigerated, buffered ophthalmic R-phenylephrine hydrochloride used for pupil dilation.
The core claim requires at least 95% initial chiral purity and retention of at least 95% of that initial purity after six months.
Claims 5 through 7 create stricter stability positions, reaching 99.5% retention.
Claims 8 through 13 cover concentrations, bottle sizes, package materials, opacity, and refrigerated labeling.
The patent does not broadly block racemic phenylephrine or every ophthalmic phenylephrine product.
The strongest infringement case would involve a product using high-purity R-phenylephrine, a buffered aqueous formulation, refrigerated storage, and a pupil-dilation indication.
The principal design-around options are racemic active ingredient, nonbuffered formulation, room-temperature storage, or omission of the claimed use.
Orange Book relevance, Paragraph IV exposure, expiration, and litigation status require review of FDA and USPTO records beyond the claim text.

FAQs About US Patent 8,859,623

Does US Patent 8,859,623 claim R-phenylephrine as a chemical compound?

No. The provided claims do not claim R-phenylephrine hydrochloride as a standalone compound. They claim a method using an ophthalmic composition containing the R enantiomer under specified purity, storage, stability, and use conditions.

Does a 2.5% phenylephrine ophthalmic product automatically infringe?

No. Concentration alone is insufficient. Claim 8 also depends on claim 1, which requires R-phenylephrine hydrochloride, an aqueous buffer, refrigerated storage, the specified chiral stability, and administration for pupil dilation.

Can a generic avoid the patent by using room-temperature storage?

Potentially. Room-temperature storage may avoid the express storage limitation, but the conclusion depends on the product’s actual handling, label, distribution records, and any other asserted patent claims.

Does an opaque 5 mL bottle create separate patent risk?

It can create exposure under claim 12 and claim 13, but only if the product also satisfies every limitation incorporated from claim 1 and claim 9. Packaging alone does not establish infringement.

Is a Paragraph IV certification required for this patent?

Only if the patent is properly listed for the relevant FDA-approved product and the applicant’s ANDA certification obligations apply. The claim text alone does not establish current Orange Book listing.

References

United States Patent and Trademark Office. (n.d.). Patent term calculator and patent term provisions. https://www.uspto.gov
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations, commonly known as the Orange Book. https://www.fda.gov
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application submissions: Patent certifications and notices. https://www.fda.gov
United States Patent and Trademark Office. (2014). U.S. Patent No. 8,859,623. Claims 1-13.

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Paragon Bioteck	PHENYLEPHRINE HYDROCHLORIDE	phenylephrine hydrochloride	SOLUTION/DROPS;OPHTHALMIC	203510-001	Mar 21, 2013	AT	RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				DILATION OF THE PUPIL	⤷ Start Trial
Paragon Bioteck	PHENYLEPHRINE HYDROCHLORIDE	phenylephrine hydrochloride	SOLUTION/DROPS;OPHTHALMIC	203510-002	Mar 21, 2013	AT	RX	Yes	Yes	⤷ Start Trial	⤷ Start Trial				DILATION OF THE PUPIL	⤷ 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
World Intellectual Property Organization (WIPO)	2015073696	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 8,859,623

Which drugs does patent 8,859,623 protect, and when does it expire?

Summary for Patent: 8,859,623