US Patent 7,683,051: Bazedoxifene Acetate Form A Claims, Expiration, and Patent Landscape

US Patent 7,683,051 protects crystalline Form A of bazedoxifene acetate, compositions containing defined proportions of Form A, selected Form A/Form B mixtures, manufacturing processes, and several therapeutic uses. Its principal commercial value is the solid-state protection for bazedoxifene acetate used in Pfizer’s DUAVEE product. The patent issued March 23, 2010, from an application filed August 15, 2005, and has a projected ordinary patent-term expiration of August 15, 2025, absent a term adjustment or extension.[1]

The patent is a polymorph patent rather than a broad composition-of-matter patent covering bazedoxifene or bazedoxifene acetate in every physical form.

What does US Patent 7,683,051 protect?

The patent has four principal claim groups:

Claim group	Claims	Protected subject matter
Form A identity	1-8	Bazedoxifene acetate Form A defined by PXRD, infrared, and DSC characteristics
Solid compositions	9-68	Form A compositions, Form A/Form B mixtures, pharmaceutical carriers, and purity thresholds
Manufacturing processes	69-83	Hydrogenation, acetate formation, and low-temperature crystallization processes
Therapeutic uses and process-defined products	84-91	Cholesterol, bone loss, breast cancer, vasomotor symptoms, and products made by specified processes

The broadest independent product claim is claim 1. It requires a crystalline polymorph of bazedoxifene acetate with PXRD characteristic peaks at approximately 12.7° and 18.5° 2θ. The claim does not require every peak listed in dependent claims 2 and 3.

Claim 1 therefore establishes a two-peak identity test. Claims 2 through 8 add progressively more analytical constraints.

How is bazedoxifene acetate Form A defined analytically?

Form A is defined through three analytical techniques:

Powder X-ray diffraction

The core PXRD limitations are:

About 12.7° 2θ; and
About 18.5° 2θ.

Claim 2 adds peaks at approximately:

16.0°;
20.7°; and
22.3°.

Claim 3 requires at least five characteristic peaks selected from a 21-peak list. The list includes peaks from approximately 9.8° through 30.7° 2θ.

Claim 4 covers a PXRD pattern substantially as shown in Figure 1. This claim can be important in litigation because the figure may provide context for peak intensity, relative positioning, and the meaning of “about,” although the precise evidentiary weight depends on the patent specification and claim construction.

Infrared spectroscopy

Claims 5 and 6 define Form A through KBr infrared spectra. Claim 5 identifies one or more characteristic absorption peaks at approximately:

1511 cm⁻¹;
1467 cm⁻¹; and
1242 cm⁻¹.

Claim 6 covers an infrared spectrum substantially as shown in Figure 2.

Differential scanning calorimetry

Claims 7 and 8 require a DSC trace with a maximum at approximately 176°C or a trace substantially as shown in Figure 3.

These analytical limitations create multiple infringement pathways. A product may satisfy the product claims through PXRD even if the infrared or DSC characteristics are not asserted. Conversely, a purity or composition claim may be supported by a combination of PXRD and quantitative solid-state analysis.

How broad are claims 1 through 8?

Claim 1 is materially broader than the dependent analytical claims because it requires only two characteristic PXRD peaks. Claims 2 and 3 narrow the scope by requiring additional peaks. Claims 4, 6, and 8 use “substantially as shown” language, which may create disputes over acceptable analytical variation.

The principal litigation issues would likely include:

Whether the accused material has the same crystal form.
How much deviation is permitted by “about.”
Whether peak position, peak intensity, or both are required.
Whether sample preparation, instrument settings, hydration, particle size, or preferred orientation affect the comparison.
Whether a mixture containing Form A and another form falls within the claim.
Whether Form A converts to another form during manufacturing, storage, or testing.

A polymorph claim generally reaches the claimed crystal form itself, not merely a product that has the same active ingredient. A manufacturer using bazedoxifene acetate Form B, an amorphous form, a hydrate, or a different salt may avoid claims 1 through 8 if the alternative material does not satisfy the claimed analytical identity.

What compositions are protected by claims 9 through 68?

Claims 9 through 35 protect solid compositions containing Form A, with dependent claims imposing increasingly high Form A content. The thresholds run from at least 50% to at least 99.9% of total bazedoxifene acetate.

Claims 46 through 67 use “consisting essentially of” and begin at 95% Form A. These claims are narrower in composition but potentially stronger against a commercial product manufactured to contain highly purified Form A.

The thresholds are cumulative in practical scope:

Form A content	Claim coverage
At least 50%	Claim 10
At least 70%	Claim 11
At least 80%	Claim 12
At least 90%	Claim 13
At least 95%	Claim 14 and claim 46 series
At least 97%	Claim 15 and claim 47
At least 98.0% to 99.9%	Claims 16-35 and 48-67

The incremental purity claims do not necessarily create independent commercial barriers. If a product contains 99.5% Form A, it would generally fall within the lower-threshold claims as well as the 99.5% claim, assuming the remaining limitations are met.

Claim 45 covers Form A with a pharmaceutically acceptable carrier. This is the principal pharmaceutical-composition claim and is more relevant to finished tablets than claims directed solely to the isolated crystal.

What Form A and Form B mixtures are covered?

Claims 36 through 44 cover compositions containing both Form A and Form B. The specified ranges include:

70% to 90% Form A and 10% to 30% Form B;
75% to 85% Form A and 15% to 25% Form B;
78% to 92% Form A and 18% to 22% Form B;
Approximately 80% Form A and 20% Form B.

Claims 41 through 44 restate similar ranges based on total bazedoxifene acetate in the composition.

These claims are unusual because they protect a defined polymorph mixture rather than requiring high-purity Form A. They could capture a manufacturing process that intentionally or incidentally produces an approximately 80:20 Form A/Form B mixture. Their practical scope depends on whether the commercial dosage form contains both forms in the claimed ratio and whether the ratio is measured before or after tableting.

A product with 80% Form A and 20% Form B may face both the mixture claims and the broader composition claims, provided it satisfies the Form A limitations incorporated through the dependency structure.

What manufacturing processes are protected?

Hydrogenation and acetate formation

Claim 69 covers a process comprising:

Reacting hexamethyleneimino benzyloxyindole with a hydrogenating reagent;
Using a solvent and, optionally, a hydrogenation catalyst;
Forming a reaction mixture containing bazedoxifene free base; and
Treating the reaction mixture with acetic acid to form bazedoxifene acetate Form A.

Dependent claims narrow the process to:

An alcohol solvent;
Ethanol;
Ethyl acetate;
Hydrogen gas;
Palladium on carbon;
An antioxidant;
Ascorbic acid;
Temperatures of approximately 25°C or lower;
Holding the mixture at approximately -20°C to 20°C for at least two hours;
Holding at approximately 20°C or 0°C for at least two hours.

These process claims are narrower than the product claims because they require specific steps and, in some cases, specific reagents or conditions. They may still be important where a generic manufacturer uses substantially the same route and produces Form A.

Low-temperature crystallization

Claim 81 covers crystallizing bazedoxifene acetate from a solution containing an alcohol while maintaining the solution below approximately 20°C. Claims 82 and 83 narrow the temperature to below approximately 10°C and specify ethanol.

This creates a separate process route that does not require the full hydrogenation sequence. A manufacturer using ethanol crystallization below 10°C could face claim 82 even if the upstream synthesis differs.

What therapeutic uses are covered?

Claims 84 through 88 cover methods using Form A to:

Lower cholesterol;
Inhibit bone loss;
Treat breast cancer;
Treat vasomotor disturbances in postmenopausal women; and
Treat hot flushes.

The FDA-approved US product DUAVEE contains conjugated estrogens and bazedoxifene and is indicated for moderate-to-severe vasomotor symptoms associated with menopause and prevention of postmenopausal osteoporosis in women with a uterus.[2]

The vasomotor and bone-loss claims therefore have the closest relationship to the approved product. The cholesterol and breast-cancer claims are not the central approved-use pathways for DUAVEE.

Claim 68 covers a solid composition containing Form A and one or more steroidal estrogens selected from mestranol and ethinyl estradiol. DUAVEE uses conjugated estrogens, not mestranol or ethinyl estradiol. On the claim language supplied, claim 68 does not directly recite the DUAVEE estrogen component.

When does US Patent 7,683,051 lose exclusivity?

The patent’s ordinary 20-year term runs from the relevant nonprovisional filing date of August 15, 2005, producing a projected expiration date of August 15, 2025.[1] The patent issued after the 1995 transition to modern patent-term rules, so the term is generally measured from the earliest effective nonprovisional filing date rather than the issue date.

The commercial risk assessment should distinguish:

Exclusivity type	Relevance
Patent term	Projected ordinary expiration: August 15, 2025
FDA new-drug exclusivity	Separate from patent protection and tied to the applicable NDA
Orange Book listing	Determines whether a listed patent must be addressed in an ANDA
Paragraph IV litigation	Can delay approval through a 30-month stay
Patent-term adjustment or extension	Could alter the ordinary expiration date if granted

The supplied record does not establish a patent-term adjustment or patent-term extension for this patent. The controlling expiration and legal status should be taken from USPTO Patent Center and the FDA Orange Book record.[3][4]

What is the Orange Book status of US 7,683,051?

DUAVEE is FDA-approved under NDA 022247. FDA Orange Book patent listings, if maintained for the product, are evaluated against the approved drug substance, formulation, or method of use rather than against every claim in the patent.[3]

A polymorph patent can be listed when it claims the drug substance in a form used by the approved product. Claims 1 through 8 and claims 9, 45, and 46 through 67 are the most plausible listing candidates because they concern Form A and pharmaceutical compositions. Process claims generally face greater listing constraints because Orange Book listing rules focus on patents that claim the drug substance, product, or approved method of use.

The patent’s relevance to an ANDA would depend on the reference product’s reliance on Form A and the generic applicant’s certification. A generic applicant could:

Certify that it will not market until expiration;
File a Paragraph III certification;
File a Paragraph IV certification alleging invalidity, unenforceability, or non-infringement; or
Attempt to formulate a product using a non-infringing bazedoxifene solid form.

Which companies are challenging bazedoxifene exclusivity?

Bazedoxifene is a small molecule, so biosimilar competition is not applicable. The relevant competitors are generic manufacturers filing ANDAs for DUAVEE or seeking approval for a bazedoxifene-containing product.

Publicly relevant competitive categories include:

Competitor category	Likely pathway
Generic DUAVEE manufacturers	ANDA referencing NDA 022247
Bazedoxifene acetate API suppliers	DMF/API supply; not necessarily FDA-approved finished products
Non-US bazedoxifene products	National or centralized non-US approvals, outside the US ANDA system
Alternative SERM products	Compete therapeutically but do not directly challenge this patent

A Paragraph IV challenge would require an ANDA applicant to address each listed patent separately. A successful non-infringement position could focus on using Form B, an amorphous form, a different salt, or a formulation in which Form A is absent or below the claimed threshold. A validity challenge could focus on anticipation, obviousness, indefiniteness of the analytical limitations, written description, enablement, or improper product-by-process scope.

How strong is the patent estate?

The patent estate is strongest against a manufacturer using the same commercial crystal form and weakest against a manufacturer that can reliably avoid Form A.

Risk factor	Assessment
Product-form protection	Strong if the accused product is Form A
Analytical proof	High technical specificity, with multiple characterization methods
Composition coverage	Broad concentration ladder from 50% through 99.9%
Process coverage	Moderate to strong where the specified hydrogenation or crystallization route is used
Method-of-use coverage	Narrower and dependent on the approved indication
Design-around potential	Meaningful if another stable polymorph or amorphous form is viable
Biosimilar exposure	None
Orange Book impact	Potentially material for an ANDA referencing DUAVEE

The analytical claims offer a practical infringement framework. PXRD is likely the primary screening tool, while infrared and DSC can corroborate identity. The composition claims increase risk where a generic product is made with highly purified Form A. The Form A/Form B mixture claims reduce the ability to avoid the patent merely by allowing controlled polymorphic impurity.

What generic launch scenarios exist?

Launch after patent expiration

This is the lowest-risk pathway if the patent has no effective extension and no other blocking patents remain. FDA approval timing, exclusivity, manufacturing readiness, and other Orange Book listings would still control the actual launch date.

Paragraph IV launch

A generic applicant could challenge the patent before expiry. The principal arguments would likely be:

The product is not Form A;
The PXRD peaks do not fall within the claim;
The composition contains less Form A than required;
The accused process does not use the claimed steps;
The claims are invalid for obviousness or indefiniteness;
The patent is unenforceable because of inequitable conduct, if supported by evidence.

A Paragraph IV filing can trigger patent litigation and a statutory 30-month approval stay under the Hatch-Waxman Act.[5]

Form B or amorphous-form design-around

A non-Form-A product could reduce direct exposure to claims 1 through 68. The design-around must account for conversion during milling, granulation, compression, storage, and dissolution testing. A nominally different starting form that converts into Form A during manufacture or storage could remain commercially exposed.

What licensing deals and litigation affect the patent?

Wyeth, the original applicant and owner associated with the bazedoxifene program, became part of Pfizer in 2009. Pfizer commercialized DUAVEE in the United States.[2]

The supplied information does not establish a license, settlement agreement, or final US litigation judgment specific to Patent 7,683,051. No such event should be treated as a confirmed constraint on the patent’s scope without a corresponding court docket, FDA patent record, SEC filing, or settlement document.

Key Takeaways

US Patent 7,683,051 is primarily a polymorph patent covering bazedoxifene acetate Form A.
Claim 1 uses two PXRD peaks, at approximately 12.7° and 18.5° 2θ, as the core identity limitations.
Dependent claims add PXRD, infrared, and DSC characteristics.
Claims 9 through 67 cover solid compositions containing specified amounts of Form A, including purity levels from 50% to 99.9%.
Claims 36 through 44 cover defined Form A/Form B mixtures, including an approximately 80:20 mixture.
Claims 69 through 83 protect selected hydrogenation, acetate formation, and low-temperature crystallization processes.
Claims 84 through 88 cover therapeutic uses, with the closest commercial relevance to postmenopausal vasomotor symptoms and bone-loss prevention.
The ordinary projected patent expiration is August 15, 2025, subject to any applicable patent-term adjustment or extension.
Biosimilar risk is irrelevant because bazedoxifene is a small molecule.
Generic risk depends heavily on whether the reference or proposed product contains Form A and whether the product is listed against DUAVEE in the Orange Book.
The most credible design-around is a stable, non-Form-A bazedoxifene acetate form that remains unchanged through manufacturing and storage.

FAQs

Does US Patent 7,683,051 cover bazedoxifene free base?

No. The claims supplied focus on crystalline bazedoxifene acetate Form A, compositions containing that form, processes producing it, and therapeutic methods using it. They do not broadly claim bazedoxifene free base.

Can a generic avoid the patent by using Form B?

Potentially. A product containing only Form B could avoid the Form A product claims, but it would not avoid claims 36 through 44 if the product contains Form A and Form B in a claimed ratio. Process claims and other Orange Book patents would also require separate analysis.

Does claim 68 cover DUAVEE?

Not on its face. Claim 68 recites mestranol or ethinyl estradiol. DUAVEE contains conjugated estrogens and bazedoxifene, so the claim language supplied does not directly identify the approved DUAVEE combination.

Is bazedoxifene subject to biosimilar competition?

No. Bazedoxifene is a chemically synthesized small molecule. US competition proceeds through the ANDA pathway, not the biosimilar pathway under the Public Health Service Act.

What laboratory tests are most important in a Form A infringement analysis?

PXRD is the primary test because claims 1 through 4 are built around diffraction peaks. Infrared spectroscopy and DSC provide additional evidence under claims 5 through 8. Testing should account for sample preparation, instrument calibration, polymorphic conversion, and mixture composition.

References

United States Patent No. 7,683,051, Bazedoxifene acetate polymorphs. U.S. Patent and Trademark Office. (2010).
U.S. Food and Drug Administration. (2013). DUAVEE prescribing information, NDA 022247. FDA.
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. FDA.
U.S. Patent and Trademark Office. (n.d.). Patent Center: U.S. Patent No. 7,683,051. USPTO.
Drug Price Competition and Patent Term Restoration Act of 1984, 21 U.S.C. § 355(j).

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Wyeth Pharms	DUAVEE	bazedoxifene acetate; estrogens, conjugated	TABLET;ORAL	022247-001	Oct 3, 2013		RX	Yes	Yes	7,683,051	⤷ Start Trial	Y	Y		PREVENTION OF POSTMENOPAUSAL OSTEOPOROSIS	⤷ Start Trial
Wyeth Pharms	DUAVEE	bazedoxifene acetate; estrogens, conjugated	TABLET;ORAL	022247-001	Oct 3, 2013		RX	Yes	Yes	7,683,051	⤷ Start Trial	Y	Y		TREATMENT OF MODERATE TO SEVERE VASOMOTOR SYMPTOMS ASSOCIATED WITH MENOPAUSE	⤷ 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
Argentina	048527	⤷ Start Trial
Australia	2005233133	⤷ Start Trial
Brazil	PI0509191	⤷ Start Trial
Canada	2561010	⤷ Start Trial
China	1938272	⤷ Start Trial
Costa Rica	8615	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 7,683,051

Which drugs does patent 7,683,051 protect, and when does it expire?

Summary for Patent: 7,683,051