United States Patent 6,692,763: Claim Scope, Expiration, Orange Book Status, and Patent Landscape

US Patent No. 6,692,763 covers low-dose estrogen treatment for postmenopausal conditions, with protection centered on achieving a serum estradiol-equivalent concentration of approximately 5 to 15 pg/mL. Its narrowest commercial relevance is transdermal estradiol delivered at approximately 5 to 15 micrograms per day, including the ultra-low-dose patch later marketed as Menostar. The patent contains method-of-treatment claims and one consumer-kit claim. It does not claim a new estradiol molecule or broadly claim every estradiol patch formulation.

The patent is no longer a current barrier to generic entry because its statutory patent term has expired. Its historical relevance was greatest for ultra-low-dose transdermal estradiol products and osteoporosis-prevention labeling.

What does US Patent 6,692,763 protect?

The patent protects a treatment strategy rather than a specific chemical entity. The central limitation is the administration of estrogen in an amount that produces a postmenopausal serum estradiol-equivalent level within a low concentration range.

Claim element	Scope under US 6,692,763
Patient	Postmenopausal subject
Active agent	Estrogen; dependent claims narrow to estradiol
Administration route	Oral, parenteral, or transdermal in claim 1; transdermal in claims 12-23
Serum target	Approximately 5-15 pg/mL estradiol equivalent
Lower target range	Approximately 5-10 pg/mL in claim 3
Oral dose	Less than 0.5 mg/day; dependent range of 0.1-0.25 mg/day
Parenteral dose	Less than approximately 20 micrograms/day; dependent range of 5-15 micrograms/day
Transdermal dose	Not more than approximately 15 micrograms/day; dependent range of 5-15 micrograms/day
Conditions	Osteoporosis, bone-density loss, fracture risk, hot flashes, headaches, nausea, and depression
Progestin limitation	Claim 16 requires substantial absence of exogenous progestin
Product format	Transdermal patch and consumer instructions in claim 15
Additional clinical step	Serum testing and confirmation of normal postmenopausal estradiol in claim 20

The independent claims are claims 1, 15, and 16. Claims 1 and 16 are method claims. Claim 15 is a kit claim.

How broad is claim 1 of US 6,692,763?

Claim 1 is broad in drug identity and administration route but narrower in pharmacokinetic outcome. It requires all of the following:

A postmenopausal subject.
A physical condition resulting from estrogen decline.
Administration of estrogen.
A resulting serum level equivalent to estradiol of approximately 5-15 pg/mL.
A listed route: oral, parenteral, or transdermal.
Treatment of one of the recited physical conditions.

The claim does not require estradiol itself. It can cover another estrogen if the resulting serum activity is expressed as an estradiol-equivalent level. Claim 4 narrows the method to estradiol.

The pharmacokinetic limitation is material. A product that delivers a nominal amount of estradiol below 15 micrograms per day may not infringe claim 1 if it does not produce the claimed serum range. Conversely, a product using a different nominal dose could potentially fall within the claim if clinical administration produces the required serum concentration.

The claim language also creates interpretation issues:

“Equivalent to a serum estradiol level” requires a method for comparing the estrogen’s biological or measured activity with estradiol.
“Not exceeding of between about 5 pg/ml and about 15 pg/ml” is grammatically irregular and may require construction as a range of approximately 5-15 pg/mL.
“Responsive to the administering” ties the serum level to the treatment rather than to endogenous estrogen production alone.
The listed condition must result from estrogen decline. A product used for a different indication would face a narrower infringement theory.

Which claims cover low-dose transdermal estradiol?

Claims 12-14 and 19-23 provide the clearest protection for an ultra-low-dose estradiol patch.

Claims 12-14

These claims require:

estradiol;
transdermal administration;
no more than approximately 15 micrograms per day; and
in claim 14, approximately 5-15 micrograms per day.

These claims focus on delivered daily dose rather than a particular patch construction. They therefore do not require a specific adhesive, backing layer, reservoir, matrix, release-control membrane, or patch area.

Claims 16-23

Claim 16 is narrower than claim 1 because it requires:

transdermal delivery;
less than approximately 20 micrograms of estradiol equivalent per day;
substantial absence of exogenous progestin;
a serum estradiol-equivalent level of approximately 5-15 pg/mL; and
treatment of a listed postmenopausal condition.

Claims 19-23 narrow the active agent to estradiol and specify delivery ranges of approximately 5-15 micrograms per day, including approximately 10 and 15 micrograms per day.

Claim 18 covers administration before hysterectomy. This limitation is unusual because it concerns the timing and surgical status of the patient, not the patch technology.

What does claim 15 protect?

Claim 15 covers a consumer kit consisting of:

A transdermal patch delivering estrogen equivalent to less than approximately 15 micrograms of estradiol per day; and
Instructions directing use of the patch to reduce osteoporotic fracture risk.

The claim is narrower than a general patch claim because the instructions must describe fracture-risk reduction. A patch sold for vasomotor symptoms with no osteoporosis-related instructions would present a weaker literal-infringement case under claim 15, although claims 12-14 and 16-23 could remain relevant depending on the use and actual dose.

The claim does not expressly require estradiol as the active ingredient. It uses an estradiol-equivalence limitation. It also does not require a specific packaging design or dosage form beyond a transdermal patch.

What are the principal legal vulnerabilities in the patent claims?

The patent’s scope is constrained by several claim-construction and validity issues.

Written description and enablement

The broadest claims cover multiple estrogens, three administration routes, several medical conditions, and a serum target. A validity challenge could argue that the specification does not adequately support the full breadth of every estrogen, route, dose, condition, and serum-equivalence relationship.

The issue is less acute for claims directed specifically to estradiol delivered transdermally at approximately 5-15 micrograms per day because those claims are technically narrower.

Indefiniteness

The phrases “equivalent to a serum estradiol level,” “about,” and “not exceeding of between” create potential indefiniteness arguments. A court would likely examine the specification, assay methods, calibration procedures, and examples to determine whether a skilled person could identify the claimed serum range with reasonable certainty.

Obviousness

Low-dose estrogen therapy could be challenged using:

earlier hormone-replacement therapy references;
known estradiol patches;
osteoporosis-prevention literature;
dose-ranging studies; and
publications discussing minimum effective estrogen exposure.

The patent’s strongest non-obviousness position would relate to the combination of an ultra-low dose, a defined serum target, and demonstrated fracture or bone-density benefit. The strongest obviousness attack would combine known estradiol patches with prior teachings to reduce estrogen exposure in postmenopausal patients.

Method-of-treatment enforcement

The claims require treatment of particular conditions. Enforcement against a generic manufacturer would therefore depend on the approved labeling, marketing, prescribing instructions, and evidence of induced use. A product sold with a label limited to a nonclaimed indication could reduce inducement exposure, although actual market use would remain relevant.

When did US Patent 6,692,763 lose exclusivity?

US 6,692,763 is expired. Its enforceable patent term ended after the statutory 20-year term measured from the applicable US nonprovisional filing date, subject to any patent-term adjustment reflected in the official USPTO record. The patent therefore does not provide a current exclusionary right against generic estradiol patches.

The patent should be distinguished from regulatory exclusivity. FDA exclusivity is independent of patent term and depends on the relevant new drug application and approval history. Any historical FDA exclusivity associated with the approved product would not restore an expired patent.

What is the Orange Book status of US 6,692,763?

US 6,692,763 was associated with the low-dose transdermal estradiol product Menostar, marketed by Bayer HealthCare Pharmaceuticals and originally associated with Berlex Laboratories. Menostar was approved as an estradiol transdermal system delivering approximately 14 micrograms per day for prevention of postmenopausal osteoporosis.

The patent’s commercial significance came from its relationship to that ultra-low-dose product and its osteoporosis-prevention indication. An Orange Book listing, where present, would have applied to the approved product and its listed use code, not to every estradiol product on the market.

Because the patent is expired, its historical Orange Book listing does not create a current Paragraph IV barrier. Current product-specific Orange Book status must be assessed against the relevant NDA and any surviving patents, not against US 6,692,763 alone. The FDA Orange Book identifies patents and exclusivity associated with approved products, while the USPTO record controls patent status and term.[2][3]

Which products and formulations were commercially relevant?

Menostar

Menostar was the closest commercial product to the patent’s core claim set. Its distinguishing characteristics were:

estradiol as the active ingredient;
transdermal delivery;
approximately 14 micrograms per day;
postmenopausal osteoporosis-prevention indication; and
no routine progestin component in the patch.

The product’s dose falls within the principal transdermal ranges in claims 13, 14, 21, and 23.

Other estradiol patches

Other transdermal estradiol products, including Vivelle-Dot, Minivelle, Climara, Alora, and generic estradiol systems, have historically been marketed at multiple dose strengths. Many use doses materially above the ultra-low-dose range, such as 25, 37.5, 50, 75, or 100 micrograms per day.

A higher-dose patch would generally fall outside the literal dose limitations of claims 13-14 and 21-23. It could still implicate claim 1 if the administered estrogen and resulting serum concentration satisfied the broader claim language, although the treatment indication and pharmacokinetic evidence would remain critical.

Are formulation patents protected by US 6,692,763?

No. US 6,692,763 is not principally a formulation patent. It does not claim:

a specific adhesive composition;
a reservoir or matrix architecture;
a rate-controlling membrane;
a particular backing layer;
a penetration enhancer;
a manufacturing process;
a defined patch surface area; or
a specific package or laminate.

Its claims are directed to treatment parameters and, in claim 15, a patch-plus-instructions kit.

A competing manufacturer could therefore develop a different ultra-low-dose patch construction without necessarily avoiding the treatment claims. Conversely, a separate formulation patent could have expired, been abandoned, or remained enforceable independently of US 6,692,763.

Were there Paragraph IV challenges or settlements?

A Paragraph IV certification is relevant only while a listed patent remains in force or otherwise creates a listed patent dispute. Because US 6,692,763 has expired, it is no longer a live Paragraph IV launch barrier.

The record supplied does not establish a particular historical Paragraph IV litigation, settlement, or 180-day generic exclusivity event tied specifically to this patent. A generic manufacturer’s historical challenge could have involved other patents, Orange Book listings, or regulatory issues associated with the relevant estradiol product.

There is no biosimilar pathway applicable to estradiol. Estradiol is a small-molecule active pharmaceutical ingredient. Generic applicants use the abbreviated new drug application pathway, not the FDA biosimilar pathway under the Public Health Service Act.[4]

What patent litigation affects this patent?

The principal current conclusion is that US 6,692,763 does not create ongoing patent litigation risk because it is expired. Any historical litigation would have needed to address infringement, validity, enforceability, or Orange Book certification during the patent’s enforceable term.

The most plausible litigation theories would have involved:

whether a generic patch delivered within the claimed daily dose;
whether the product produced the required 5-15 pg/mL serum level;
whether the label induced treatment of osteoporosis or fracture risk;
whether “estradiol equivalent” was sufficiently definite;
whether the claims were obvious over earlier hormone-replacement therapy;
whether the relevant patent was properly listed for the approved product; and
whether the patent covered the product’s specific approved indication.

No surviving settlement restriction can be inferred from the expired patent alone.

How strong was the patent estate for ultra-low-dose estrogen?

The patent had moderate historical strength against products closely matching its central commercial profile, but limited strength against the broader estrogen market.

Risk category	Historical assessment
Ultra-low-dose estradiol patch	Moderate to high while unexpired
Estradiol patch above 15 micrograms/day	Lower
Oral estradiol	Moderate only if serum and indication limitations were met
Non-estradiol estrogen	Fact-dependent and technically difficult
Osteoporosis-prevention labeling	Higher risk
Vasomotor-symptom-only labeling	Lower risk under the narrowest claims
Different patch formulation	Could still infringe method claims
Generic entry today	No patent-term barrier from US 6,692,763
Biosimilar exposure	Not applicable

The patent’s practical value was concentrated in a narrow product-and-indication combination: an ultra-low-dose transdermal estradiol system used for postmenopausal osteoporosis prevention.

What generic launch scenarios existed?

During the patent term, three generic-launch scenarios were relevant.

Design-around by dose

A manufacturer could select a dose above the claimed ultra-low-dose ranges. This approach would have reduced literal risk under claims 13, 14, and 21-23, but it could have altered the product’s clinical profile and prevented reliance on the same low-dose osteoporosis-prevention positioning.

Label carve-out

A generic sponsor could seek approval with a label that omitted a patented indication, subject to FDA requirements and the scope of the remaining approved uses. This strategy would have reduced induced-infringement exposure but would not automatically defeat method claims based on actual prescribing or other label language.

Paragraph IV challenge

A sponsor could certify that the patent was invalid, unenforceable, or not infringed. After expiration, an ANDA applicant could proceed without relying on a Paragraph IV dispute against this patent, subject to other applicable patents and regulatory requirements.

What geographic coverage did the patent have?

US 6,692,763 provided protection only in the United States. Foreign counterparts, if any, required separate national examination, maintenance, and term analysis. A US expiration did not determine the status of corresponding patents in Europe, Canada, Japan, or other markets.

Geographic freedom to operate therefore required separate review of:

PCT filings and national-phase entries;
granted foreign patents;
patent-term adjustments or supplementary protection certificates;
local Orange Book equivalents;
regulatory exclusivity; and
country-specific generic approval rules.

Key Takeaways

US 6,692,763 is a low-dose estrogen method-of-treatment patent.
Its central technical limitation is a serum estradiol-equivalent level of approximately 5-15 pg/mL.
Claims 12-14 and 16-23 most directly target ultra-low-dose transdermal estradiol.
Claim 15 covers a transdermal patch kit with osteoporosis-fracture-risk instructions.
The patent does not broadly claim every estradiol patch or a specific patch formulation.
Menostar was the principal commercial product aligned with the patent’s claimed dose and use.
The patent is expired and no longer presents a current US patent-term barrier to generic estradiol entry.
No biosimilar pathway applies because estradiol is a small molecule.
Current freedom-to-operate analysis must focus on other patents, product-specific Orange Book listings, formulation rights, manufacturing rights, and regulatory requirements.

FAQs

Does US 6,692,763 cover all estradiol patches?

No. It targets particular treatment methods, dose ranges, serum levels, patient populations, and conditions. Higher-dose patches and patches used for different indications may fall outside the narrowest claims.

Does a 14-microgram estradiol patch fall within the patent claims?

A 14-microgram-per-day transdermal estradiol patch falls within the express numerical ranges of several claims, assuming the other limitations, including patient status, condition, and serum estradiol-equivalent level, are satisfied. The patent is expired.

Does the patent require a specific estradiol patch design?

No. The claims do not require a particular adhesive, reservoir, matrix, membrane, backing, or manufacturing process.

Can a generic manufacturer rely on an indication carve-out?

Potentially, but the result depends on the approved label, omitted indication, marketing conduct, prescribing evidence, and any other applicable patents. A carve-out would not itself eliminate every infringement theory.

Does patent expiration eliminate all regulatory barriers to generic Menostar?

No. Patent expiration removes the exclusionary effect of this patent. FDA approval requirements, reference-product issues, manufacturing standards, labeling, market availability, and other surviving rights remain separate considerations.

References

United States Patent and Trademark Office. (2004). US Patent No. 6,692,763, Low dose estrogen therapy.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book.
U.S. Food and Drug Administration. (2004). Menostar (estradiol transdermal system) prescribing information.
U.S. Food and Drug Administration. (n.d.). Abbreviated new drug application (ANDA): Generics.
U.S. Food and Drug Administration. (n.d.). Purple Book: Database of licensed biological products.

PCT Information
PCT Filed	November 21, 1998	PCT Application Number:	PCT/US98/24677
PCT Publication Date:	June 03, 1999	PCT Publication Number:	WO99/26631

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Austria	291430	⤷ Start Trial
Austria	383862	⤷ Start Trial
Australia	1591499	⤷ Start Trial
Australia	760108	⤷ Start Trial
Brazil	9814984	⤷ Start Trial
Canada	2306881	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 6,692,763

Summary for Patent: 6,692,763