US Patent 5,914,334: Tazarotene Gel Claims, Expiration, and Patent Landscape

US Patent 5,914,334 protects a specific topical tazarotene gel platform, not tazarotene as a molecule. Its strongest coverage is directed to the combined use of Polysorbate 40, Poloxamer 407, and hexylene glycol within narrow concentration limits. The patent also claims a manufacturing process and functional gel characteristics involving solubility, stability, and drug release.

The patent issued on June 22, 1999, and its 20-year term has expired. It no longer creates a US patent barrier to generic tazarotene products. Its historical importance remains relevant for freedom-to-operate analysis because it illustrates the formulation architecture used for branded Tazorac gel products.

What drug and formulation does US Patent 5,914,334 cover?

The active ingredient is tazarotene, chemically identified in the claims as:

Ethyl 6-[2-(4,4-dimethylthiochroman-6-yl)ethynyl]nicotinate.

Tazarotene is a topical retinoid used for acne and plaque psoriasis. The patent claims a stable gel in which the active ingredient is solubilized and released through a vehicle system containing Polysorbate 40, Poloxamer 407, and hexylene glycol.

The claims also identify several conventional formulation ingredients:

Ingredient	Claimed role or significance
Water	Aqueous carrier in claims 1 and 3
Edetate disodium	Chelating agent
Ascorbic acid	Antioxidant or stabilizer
Carbomer 934P	Gelling and viscosity agent
Poloxamer 407	Solubilizer and vehicle component
Polyethylene glycol	Co-solvent
Polysorbate 40	Surfactant and solubilizer
Hexylene glycol	Co-solvent and penetration-related vehicle
Butylated hydroxytoluene	Antioxidant
Butylated hydroxyanisole	Antioxidant
Benzyl alcohol	Preservative and solvent
Tromethamine	Neutralizing and pH-adjusting agent

The claims do not cover every tazarotene gel. They require a particular combination of excipients, concentration limits, and, for some claims, functional performance.

How many independent claims does US Patent 5,914,334 contain?

The patent has five independent claims: claims 1, 3, 5, 6, and 7.

Claim	Claim type	Main subject matter
1	Composition	Stable aqueous gel for acne and psoriasis with a specified excipient package
2	Dependent composition	Claim 1 with specified preferred concentrations
3	Manufacturing method	Four-part mixing and homogenization process
4	Dependent method claim	Claim 3 with specified preferred concentrations
5	Composition	Tazarotene gel with vehicles controlling drug release
6	Composition	Tazarotene gel with vehicles controlling solubility
7	Composition	Tazarotene gel controlling both solubility and release
8	Dependent composition	Claim 7 with specified preferred concentrations

The broadest practical composition claims are claims 5, 6, and 7 because they do not expressly require the full list of ingredients appearing in claim 1. They do, however, require the claimed vehicle combination and functional limitations.

What are the concentration limits in the patent?

The central numerical limitations are:

Excipient	Maximum amount in independent claims	Preferred amount in dependent claims
Polysorbate 40	Up to about 0.4% by weight	About 0.32% by weight
Poloxamer 407	Up to about 0.4% by weight	About 0.18% by weight
Hexylene glycol	Up to about 2% by weight	About 2% by weight

The dependent claims narrow the formulation to the preferred concentrations of approximately 0.32% Polysorbate 40, 0.18% Poloxamer 407, and 2% hexylene glycol.

The phrase “up to about” creates a range extending from zero or a very low amount to the stated upper limit, subject to ordinary claim-construction principles. The dependent claims are narrower because they require the specified target concentrations.

What does claim 1 protect?

Claim 1 requires all of the following:

A stable gel formulation.
Topical treatment of both acne and psoriasis.
An effective amount of tazarotene.
A carrier containing water.
Edetate disodium.
Ascorbic acid.
Carbomer 934P.
Poloxamer 407.
Polyethylene glycol.
Polysorbate 40.
Hexylene glycol.
Butylated hydroxytoluene.
Butylated hydroxyanisole.
Benzyl alcohol.
Tromethamine.
Polysorbate 40 at no more than about 0.4% by weight.
Poloxamer 407 at no more than about 0.4% by weight.
Hexylene glycol at no more than about 2% by weight.

A competing product that omits one required ingredient may avoid literal infringement of claim 1, although it could still implicate claims 5, 6, or 7 if it uses the three claimed vehicles and satisfies the relevant functional limitations.

What do claims 5, 6, and 7 protect?

Claim 5: drug-release control

Claim 5 requires:

Tazarotene;
a stable gel;
Polysorbate 40, Poloxamer 407, and hexylene glycol;
vehicle amounts and combinations that control release of tazarotene to the skin.

This claim does not expressly require the full aqueous excipient package of claim 1. It also does not expressly require water, Carbomer 934P, antioxidants, benzyl alcohol, or tromethamine.

Claim 6: solubility control

Claim 6 is directed to a tazarotene gel in which the three vehicles control the solubility of tazarotene. A formulation may fall within this claim even if its principal distinction from the branded formulation is a different gel base, provided the accused product uses the claimed vehicle combination and meets the functional limitation.

Claim 7: combined solubility and release control

Claim 7 is the broadest functional composition claim in the patent because it requires the vehicle combination to control both:

the solubility of tazarotene in the gel; and
release of tazarotene to the skin.

Claim 8 narrows claim 7 to the preferred concentrations.

The practical weakness of claims 5 through 7 is that “control solubility” and “control release” may require technical evidence. A product does not necessarily infringe merely because it contains the three named excipients. The patent owner would likely need to establish that the formulation and the excipient combination perform the claimed control functions.

What does the manufacturing method claim cover?

Claim 3 covers a multipart manufacturing process:

Dispersing Carbomer 934P in water with edetate disodium and ascorbic acid to form Part I.
Mixing water and Poloxamer 407 to form Part II.
Adding Part II to Part I and homogenizing.
Heating polyethylene glycol, Polysorbate 40, hexylene glycol, butylated hydroxytoluene, and butylated hydroxyanisole.
Cooling that mixture and adding benzyl alcohol and tazarotene to form Part III.
Mixing water and tromethamine to form Part IV.
Adding Part III to Parts I and II, followed by Part IV.
Mixing until homogeneous.
Maintaining the claimed excipient limits.

A manufacturer can avoid literal infringement of claim 3 by using a materially different sequence, different premixes, different heating or cooling steps, or a different neutralization process. Avoiding the process claim does not automatically avoid the composition claims.

Claim 4 is unusual because it states “the formulation according to claim 3,” even though claim 3 is a process claim. The likely substantive intent is to narrow the process-produced formulation to the preferred excipient concentrations. Claim interpretation would depend on the patent’s specification and prosecution history.

What is the scope of the “stable gel” limitation?

“Stable” is likely directed to physical and chemical stability during storage, including:

maintenance of tazarotene concentration;
prevention of precipitation or crystallization;
preservation of gel homogeneity;
acceptable viscosity;
color and appearance retention; and
compatibility of the active ingredient with the vehicle system.

A formulation can be a gel without satisfying the patent’s stability requirement. Stability may be demonstrated through accelerated and long-term testing, assay data, impurity profiles, appearance testing, and rheological measurements.

The claim language does not state a single numerical shelf-life threshold. The specification, examples, and prosecution history would therefore be important in determining how the term is construed.

How does the “nonaqueous vehicles” language affect claim construction?

Claims 5, 6, and 7 describe the vehicles as “nonaqueous vehicles,” while claims 1 and 3 expressly include water. This creates a potential internal construction issue.

The most commercially sensible interpretation is that Polysorbate 40, Poloxamer 407, and hexylene glycol are the nonaqueous or non-water vehicle components, while the overall formulation may still contain water. Reading claims 5 through 7 as requiring an entirely anhydrous product would conflict with the disclosed gel technology and could exclude the formulations described in the patent.

The misspelling “nonagueous” in the supplied claim text is a typographical error and does not materially change the intended meaning.

When did US Patent 5,914,334 lose exclusivity?

The patent’s term expired in 2017, based on the 20-year patent-term framework applicable to its filing date. The exact expiration calculation depends on the recorded application filing date, priority claims, terminal disclaimers, and any patent-term adjustment.

Because the patent issued in 1999 and was based on a pre-1995 priority framework only if an earlier application was involved, the controlling term must be calculated from the relevant US nonprovisional filing date under 35 U.S.C. § 154. Public patent records identify the patent as expired rather than active. [1][2]

The expiration eliminates ordinary US infringement liability for conduct occurring after expiration. It does not erase historical infringement claims that accrued while the patent was enforceable, subject to applicable limitations periods and other defenses.

What was the FDA and Orange Book status of the patent?

Tazarotene was approved as a topical prescription retinoid, including gel and cream dosage forms, for acne and plaque psoriasis indications. The branded product was marketed as Tazorac.

The Orange Book analysis for tazarotene must distinguish between:

active-ingredient patents;
formulation patents;
method-of-use patents;
pediatric exclusivity;
regulatory exclusivity; and
patents listed against a particular NDA and dosage form.

US Patent 5,914,334 was a formulation patent. Its value depended on whether it was listed against the relevant Tazorac product and whether a generic applicant had to address it in an ANDA certification. Once the patent expired, it ceased to provide a forward-looking Orange Book patent barrier. FDA approval of generic tazarotene products is governed by the ANDA pathway, not a biosimilar pathway. [3][4]

Were Paragraph IV challenges relevant?

Paragraph IV challenges would have been relevant while the patent was listed and unexpired. An ANDA applicant could certify that the patent was invalid, unenforceable, or would not be infringed by the proposed generic product.

A Paragraph IV certification could lead to:

a patent-infringement action within 45 days;
a 30-month stay of FDA approval in qualifying circumstances;
settlement negotiations;
a first-filer position for a generic applicant; or
approval after patent expiration if the patent issue was resolved.

For an expired formulation patent, a new Paragraph IV challenge generally has no practical forward-looking value because the patent no longer blocks approval or commercial launch. Historical certification and litigation records may still matter for antitrust, settlement, or damages analysis.

Which companies challenged tazarotene exclusivity?

The commercially relevant competitive group consisted of:

Company type	Product or role
Allergan and predecessor commercial entities	Branded Tazorac products and related intellectual property
Generic topical-drug manufacturers	ANDA products containing tazarotene gel or cream
Contract manufacturers	Potential suppliers of bulk tazarotene, gel intermediates, or finished dosage forms
Dermatology-focused marketers	Generic or authorized-generic distribution channels

A complete company-by-company Paragraph IV and settlement chronology cannot be established from the claim text alone. The patent itself does not identify all ANDA applicants, litigation defendants, or settlement parties.

What is the patent strength of US Patent 5,914,334?

Historical strength

The patent had meaningful historical strength because it claimed a formulation problem that was narrower than the tazarotene molecule but potentially difficult to design around without changing product performance. The combination of solubilizers, gel-forming components, antioxidants, and concentration limits could support a credible formulation patent position.

Current strength

Its current enforceability is zero because the US patent term has expired. It has no blocking value against new generic products.

Claim-by-claim strength

Claim group	Historical breadth	Design-around potential
Claims 1 and 2	Narrow due to full excipient list	High
Claims 3 and 4	Narrow process sequence	High to moderate
Claim 5	Broader functional release claim	Moderate
Claim 6	Broader functional solubility claim	Moderate
Claims 7 and 8	Combined functional limitation	Moderate
Entire patent today	No enforceable term	Complete as a forward-looking barrier

What manufacturing and formulation barriers remain after patent expiration?

Patent expiration does not remove technical barriers. A generic developer still must address:

tazarotene solubility;
precipitation control;
gel viscosity;
preservative effectiveness;
antioxidant compatibility;
microbial limits;
tube or pump compatibility;
dose uniformity;
in vitro release;
product stability;
irritation and tolerability;
scale-up reproducibility; and
FDA bioequivalence expectations for a topical product.

These are regulatory and development barriers, not patent exclusivity barriers. A manufacturer can use a different vehicle system and still face substantial formulation-development work.

How does this patent compare with molecule and method-of-use patents?

US Patent 5,914,334 is materially narrower than a composition-of-matter patent covering tazarotene itself. A molecule patent can block use of the active ingredient across multiple formulations and indications. This patent covers only defined gel formulations and a related manufacturing process.

It is also narrower than a broad method-of-treatment patent covering topical tazarotene for acne or psoriasis. A method patent may be infringed by treating patients according to the claimed regimen even when the formulation differs. The 5,914,334 patent instead concentrates on vehicle composition, excipient levels, stability, solubility, release, and processing.

What is the generic launch risk for tazarotene products?

For US commercial planning, the patent-specific generic launch risk is low because the patent has expired. Generic launch risk instead depends on:

FDA approval status;
availability of tazarotene active pharmaceutical ingredient;
topical bioequivalence requirements;
formulation development;
manufacturing economics;
competing generic approvals;
state substitution rules; and
reimbursement and pricing pressure.

There is no biosimilar issue. Tazarotene is a chemically synthesized small molecule, so competing products proceed through the generic-drug framework rather than the Public Health Service Act biosimilar pathway.

Key Takeaways

US Patent 5,914,334 covers tazarotene gel formulations and a manufacturing process.
Its central vehicle combination is Polysorbate 40, Poloxamer 407, and hexylene glycol.
The principal numerical limits are about 0.4% Polysorbate 40, about 0.4% Poloxamer 407, and about 2% hexylene glycol.
Claims 1 and 3 are narrow because they require a detailed excipient package or process sequence.
Claims 5 through 7 are broader but depend on functional limitations involving solubility and drug release.
The patent does not broadly claim tazarotene as an active ingredient.
The US patent term expired in 2017.
It no longer blocks generic tazarotene development or launch.
Tazarotene products are subject to the ANDA pathway, not biosimilar regulation.
Remaining commercial barriers are primarily formulation, manufacturing, FDA approval, and market-access issues.

FAQs About US Patent 5,914,334

Does US Patent 5,914,334 cover all tazarotene products?

No. It covers specified tazarotene gel formulations, a defined vehicle combination, functional solubility or release characteristics, and a manufacturing sequence. It does not broadly cover every tazarotene formulation.

Can a generic use a different gel-forming agent?

Historically, a different gel-forming agent could help avoid claims requiring Carbomer 934P, particularly claims 1 through 4. Claims 5 through 7 require the claimed vehicle combination and functional characteristics, but do not expressly require Carbomer 934P.

Does the patent cover tazarotene cream?

Not expressly. The claims are directed to a gel formulation. A cream containing tazarotene would require separate analysis under the literal language of each claim and any other relevant patent.

Is tazarotene subject to biosimilar competition?

No. Tazarotene is a small-molecule drug. Generic tazarotene products are approved through the ANDA pathway rather than the biosimilar pathway.

Does patent expiration eliminate FDA requirements for a generic tazarotene gel?

No. Expiration removes the patent barrier but does not eliminate FDA requirements concerning pharmaceutical equivalence, bioequivalence, stability, manufacturing quality, labeling, and product approval.

References

United States Patent and Trademark Office. (1999). U.S. Patent No. 5,914,334, Stable gel formulation containing tazarotene.
United States Code. (2023). 35 U.S.C. § 154: Contents and term of patent; provisional rights.
U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2024). Approved drug products: Tazarotene topical products and labeling information.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	215836	⤷ Start Trial
Austria	336263	⤷ Start Trial
Australia	2821895	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 5,914,334

Summary for Patent: 5,914,334