United States Patent 11,529,308: Scope, Claim Construction, Exclusivity and Patent Landscape for the Segesterone Acetate Vaginal Ring

United States Patent No. 11,529,308 protects a specific reusable contraceptive vaginal ring architecture containing segesterone acetate and ethinyl estradiol. Its principal value is not a broad claim to the active ingredients. The patent combines a dual-core silicone ring design, defined curing chemistry, adhesive loading, drug quantities, release rates, and long-term ethinyl estradiol recovery.

The claim is narrow in structure but potentially material for generic or follow-on products that replicate the Annovera-type ring. A competing product that uses the same two-channel ring, silicone chemistry, drug loading, release profile, and storage-performance characteristics could face a substantial infringement risk. A product using a different core arrangement, polymer system, adhesive strategy, or drug-release design may avoid literal infringement even if it delivers the same hormones.

What drug and product does United States Patent 11,529,308 cover?

US 11,529,308 covers a reusable vaginal ring system for preventing pregnancy that releases:

Component	Claimed amount or performance
Segesterone acetate	Approximately 103 mg
Ethinyl estradiol	Approximately 17.4 mg
Segesterone acetate release	Approximately 0.15 mg/day
Ethinyl estradiol release	Approximately 0.013 mg/day
Use period	Up to 13 cycles of 21 days each
Storage condition	18 months at 25°C and 60% relative humidity
Ethinyl estradiol recovery	Approximately 80% to 90%

The claimed system corresponds closely to the technical profile of Annovera, a reusable vaginal contraceptive ring containing segesterone acetate and ethinyl estradiol. Annovera was approved by the U.S. Food and Drug Administration in 2018 under NDA 210186.[2]

The patent does not claim segesterone acetate or ethinyl estradiol as chemical compounds. It claims their incorporation into a defined drug-device combination.

What are the independent claim limitations in US 11,529,308?

Claim 1 is the controlling claim. It requires all of the following elements:

A reusable vaginal ring for contraception.
A silicone elastomer ring body.
Platinum concentration of approximately 3 ppm to approximately 10 ppm before curing.
Hydride-to-vinyl ratio of approximately 1:1 to approximately 1.3:1 before curing.
A first cylindrical channel adapted to receive a first cylindrical core.
A second cylindrical channel adapted to receive a second cylindrical core.
Medical adhesive securing the cores in the channels.
A first core containing:
- Two condensation-cure silicone elastomers;
- Dibutyltin dilaurate;
- A viscosity agent.
A second core containing:
- A third condensation-cure silicone elastomer;
- Dibutyltin dilaurate.
Substantially complete adhesive communication between the circumferential surfaces of the cores and channel walls.
Approximately 103 mg of segesterone acetate.
Approximately 17.4 mg of ethinyl estradiol.
The hormones contained within the cores.
The specified average daily release rates.
Release for up to 13 21-day cycles.
Recovery of approximately 80% to 90% of ethinyl estradiol after the stated storage period.

Each limitation matters. A generic applicant cannot avoid the patent merely by changing the trade name, external dimensions, or manufacturing site if the accused product still includes the claimed technical elements.

How does claim 1 divide between device, formulation, manufacturing and performance limitations?

The claim has four distinct technical layers.

Ring architecture

The ring body has two separate cylindrical channels. Each channel receives a cylindrical drug-containing core. The design is different from a single homogeneous drug-loaded elastomer ring or a ring with a continuous annular drug matrix.

Polymer and catalyst chemistry

The ring body is defined by platinum concentration and hydride/vinyl ratio before curing. The cores use condensation-cure silicone elastomers and dibutyltin dilaurate. These limitations target manufacturing composition and curing conditions rather than only the finished product's physical appearance.

The platinum concentration and hydride/vinyl ratio are particularly important in freedom-to-operate analysis. A manufacturer may use a visibly identical ring while attempting to avoid the claim through a different catalyst concentration or crosslinking ratio. That strategy would require analytical testing because the limitations concern composition before curing.

Adhesive interface

The cores are not merely positioned inside the channels. The claim requires adhesive communication between substantially all of the relevant circumferential surfaces and the channel walls. Dependent claims 4 and 5 expand this requirement to all of the circumferential surfaces and faces.

The adhesive limitations can create both infringement risk and design-around opportunities. A ring using mechanical retention, an overmolded core, partial adhesive contact, or a different channel geometry may present a noninfringement position.

Drug loading and release performance

The claim specifies both total drug content and average release rates. It also requires a long-term recovery result for ethinyl estradiol after storage.

These features make the claim a hybrid composition, device and performance claim. A product could contain the same two hormones but fall outside the claim if it has materially different loading, daily release, storage recovery, or use duration.

What do dependent claims 2 through 6 add?

Claim	Added limitation	Commercial significance
2	Total adhesive in both channels of approximately 160 mg to 220 mg	Narrows adhesive loading range
3	First channel contains approximately 90 mg to 130 mg adhesive; second contains approximately 30 mg to 90 mg	Adds channel-specific adhesive distribution
4	All of each circumferential surface is in adhesive communication with the corresponding wall	Tightens the interface requirement
5	Approximately all of the circumferential faces also communicate with the channel walls	Covers end-face or face-adjacent adhesion
6	One core contains segesterone acetate; the other contains both segesterone acetate and ethinyl estradiol	Claims a particular drug allocation between cores

Claim 6 is commercially important because it limits the patent to a particular distribution of active ingredients. A ring in which one core contains only segesterone acetate and the other contains both hormones may satisfy the claim. A ring in which both cores contain identical hormone mixtures may not satisfy claim 6, although it could still be assessed against claim 1.

Claims 2 through 5 provide narrower fallback positions if a court rejects or limits some interpretation of claim 1. Claim 6 may be especially relevant to product teardown and formulation comparison.

What does “approximately” mean in this patent?

The claims use “approximately” for drug amounts, catalyst concentration, hydride/vinyl ratio, release rates, adhesive quantities and recovery percentages.

“Approximately” does not create an unlimited range. Its scope would generally depend on the intrinsic evidence, including the specification, examples, analytical precision, manufacturing tolerances and prosecution history. The relevant inquiry is whether a product falls within the ordinary technical meaning of the term in the context of this patent.

For an accused ring, the following measurements would likely be material:

Platinum concentration before curing;
Hydride-to-vinyl ratio;
Total and channel-specific adhesive mass;
Core dimensions and composition;
Segesterone acetate and ethinyl estradiol loading;
Daily release over the intended use period;
Residual ethinyl estradiol after stability storage;
Whether the core surfaces are substantially continuously adhered to the channel walls.

A product outside a nominal numerical value may still create risk if the difference is within manufacturing tolerance or is treated as an equivalent technical result. Conversely, a substantial formulation change can support a noninfringement position.

What patent rights does US 11,529,308 provide?

US 11,529,308 is an issued utility patent. Its claims can be asserted against making, using, selling, offering for sale or importing a ring system that meets the claim limitations under 35 U.S.C. § 271.

The patent does not automatically block every contraceptive ring, every product containing segesterone acetate, or every product containing ethinyl estradiol. It is product-specific and architecture-specific.

The principal infringement theories are:

Theory	Relevance
Literal infringement	Each claim limitation is present in the accused ring
Doctrine of equivalents	A materially different element performs substantially the same function in substantially the same way to obtain substantially the same result
Indirect infringement	A supplier or manufacturer contributes to or induces conduct that infringes
Method-of-use infringement	Less central here because the asserted claims are system claims rather than treatment-method claims

The storage-recovery limitation may be litigated as a product characteristic or as a limitation that must be demonstrated through testing. A generic applicant could challenge whether the limitation is sufficiently definite, whether it is inherent in the product, and whether the claimed result is met across the scope of the claim.

When does US 11,529,308 expire?

US 11,529,308 issued on December 20, 2022. Its ordinary term is generally calculated as 20 years from the earliest effective nonprovisional U.S. filing date in the relevant family, subject to patent-term adjustment, terminal disclaimers and any applicable patent-term extension.

The issue date alone does not establish the expiration date. The authoritative term calculation requires the patent's continuity data, earliest effective filing date, terminal-disclaimer status and USPTO patent-term adjustment record.[1]

The maintenance-fee schedule based on the issue date is:

Maintenance-fee stage	Approximate due date
3.5 years after issue	June 20, 2026
7.5 years after issue	June 20, 2030
11.5 years after issue	June 20, 2034

Failure to pay required maintenance fees can cause expiration before the statutory term, subject to statutory reinstatement procedures.

Is US 11,529,308 listed in the FDA Orange Book?

Orange Book status must be determined from the current FDA publication for NDA 210186. FDA-listed patent status can change through patent listing, delisting, expiration, correction or regulatory updates.[3]

For an NDA product such as Annovera, the relevant patent questions are:

Whether US 11,529,308 is listed for NDA 210186;
Whether the listing identifies the patent as covering the drug substance, drug product or method of use;
Whether the patent is identified with a use code;
Whether the patent's claims cover the approved reusable ring;
Whether the listed patent remains unexpired and enforceable.

A device-combination patent can create Orange Book relevance when the claimed ring is part of the approved drug product. Its listing does not establish validity or infringement. The Orange Book is an FDA listing mechanism, not a judicial determination of patent scope.[3]

What FDA exclusivity applies to Annovera?

Annovera received FDA approval on August 10, 2018. Regulatory exclusivity and patent exclusivity are separate.

Protection	General effect
New chemical entity exclusivity	Can delay submission of an ANDA for the qualifying active ingredient for five years, subject to statutory exceptions
Three-year clinical-investigation exclusivity	Can restrict approval of certain applications relying on the approved product's clinical investigations
Patent protection	Can delay approval or create litigation risk based on listed patents
Pediatric exclusivity	Adds six months only if granted after qualifying pediatric requirements
Orphan exclusivity	Not the primary protection for contraceptive use

The relevant FDA exclusivity dates should be confirmed in the current Orange Book and NDA regulatory history. Patent expiry will likely be more important for commercial launch timing than the original NCE period because the product's principal patent estate extends beyond the 2018 approval date.

Which companies own, commercialize or may challenge the product?

The commercial and development history involves multiple entities.

Entity	Role
Population Council	Developer and patent-originating organization associated with the segesterone acetate vaginal ring technology
TherapeuticsMD	Original U.S. commercial sponsor and NDA holder associated with Annovera
Mayne Pharma	Acquired U.S. commercial rights and has been associated with U.S. commercialization
Generic manufacturers	Potential ANDA applicants requiring a Paragraph IV, Section viii or Paragraph III strategy depending on the listed patent claims

No broad generic market has developed for a reusable segesterone acetate/ethinyl estradiol ring comparable to the established etonogestrel/ethinyl estradiol ring market. A potential ANDA challenger would face both patent and technical-development barriers.

What Paragraph IV risks exist for a generic Annovera ring?

An ANDA applicant could use several certification strategies:

Paragraph III certification

The applicant accepts that a listed patent remains valid and enforceable and proposes approval after patent expiration. This avoids immediate patent litigation but delays launch.

Paragraph IV certification

The applicant asserts that the listed patent is invalid, unenforceable or will not be infringed. The NDA holder may bring a Hatch-Waxman infringement action within 45 days, potentially triggering a 30-month stay of approval under the statutory framework.[4]

Section viii statement

A section viii statement could be relevant to a method-of-use patent that is not necessary for the proposed label. It is less useful against a patent claiming the physical vaginal ring itself.

For US 11,529,308, a Paragraph IV position would most likely focus on:

Noninfringement based on a different channel or core configuration;
Different silicone curing chemistry;
Different catalyst system;
Absence of substantially complete adhesive contact;
Different drug allocation;
Release rates outside the claim;
Failure to meet the storage-recovery limitation;
Invalidity based on anticipation or obviousness;
Indefiniteness of “approximately” or “approximately all”;
Written-description or enablement challenges to the combined limitations.

What design-around strategies could avoid the patent?

Potential design-around categories include:

Design-around category	Possible technical change
Ring body	Use a different elastomer or a different crosslinked silicone system
Core configuration	Use one core, more than two cores, or a non-cylindrical core
Channel design	Use an annular drug matrix, external drug reservoir or non-cylindrical channel
Adhesion	Use mechanical retention, overmolding or partial adhesion
Catalyst chemistry	Change platinum concentration, hydride/vinyl ratio or curing mechanism
Core chemistry	Use addition-cure rather than condensation-cure elastomers
Drug distribution	Place each hormone in a separate core or use a different allocation
Drug loading	Change the total loading while maintaining therapeutic exposure through another design
Release profile	Use a different release rate or shorter reuse period
Packaging and stability	Use a formulation that does not produce the claimed recovery range

Design-around analysis must assess the entire patent family, not only claim 1. A change that avoids US 11,529,308 may still fall within another formulation, manufacturing, dosage-form or method-of-use patent.

How strong is the patent estate around the segesterone acetate ring?

US 11,529,308 has meaningful commercial relevance but a narrower claim footprint than a basic active-ingredient patent.

Strength factors

The claim covers the complete drug-device system rather than an abstract use.
It includes detailed structural and manufacturing limitations that may map closely to the commercial ring.
It covers long-duration reuse, a central product attribute.
The claimed performance parameters can make a competing product difficult to distinguish if it uses the same development platform.
Dependent claims provide narrower positions concerning adhesive mass, adhesive coverage and drug allocation.

Vulnerability factors

The claim contains many cumulative limitations.
A challenger can avoid literal infringement through one material architecture or formulation change.
“Approximately” and “approximately all” may invite claim-construction disputes.
The storage-recovery limitation may raise proof and definiteness issues.
Prior art involving silicone vaginal rings, steroid reservoirs, adhesive bonding and controlled release could support obviousness arguments.
The claim does not independently protect the chemical entities or all contraceptive uses of the hormones.

The patent is strongest against a substantially copied Annovera-style ring. It is weaker against a redesigned ring using a different drug-reservoir architecture.

What litigation or settlement activity affects US 11,529,308?

A complete litigation assessment requires a current review of PACER, the USPTO Patent Center, FDA Paragraph IV notices and the Orange Book. The patent itself does not establish whether a Paragraph IV notice has been served, whether a complaint was filed, or whether a settlement agreement exists.

For transaction and launch-risk analysis, the relevant records are:

District court complaints naming the NDA holder, patent owner or licensee.
Paragraph IV notices and any statutory 45-day litigation response.
ANDA litigation docket activity.
Patent-term adjustment and terminal-disclaimer records.
FDA approval status of any abbreviated or 505(b)(2) application.
Settlement agreements and any Federal Trade Commission review.
License or commercialization agreements governing the patent family.

No conclusion about a settlement or active Paragraph IV challenge should be drawn from the patent number alone.

How does the patent compare with competing contraceptive ring patents?

Product	Hormones	Reuse period	Patent-risk relationship
Annovera	Segesterone acetate and ethinyl estradiol	Up to 13 cycles	Directly relevant
NuvaRing and generic equivalents	Etonogestrel and ethinyl estradiol	Typically one cycle	Different active progestin and product architecture
Ornibel and related products	Etonogestrel and ethinyl estradiol	Typically one cycle	Generally outside the active-ingredient limitation
Other investigational rings	Varies	Varies	Risk depends on dual-core silicone and formulation design

The strongest commercial overlap is with a reusable segesterone acetate/ethinyl estradiol ring. Conventional etonogestrel rings compete therapeutically but are less likely to infringe claim 1 because they do not contain segesterone acetate.

What revenue exposure does the patent create?

The patent protects a product with limited direct substitutes in the reusable hormonal ring segment. Its economic value depends on:

Annovera net sales and prescription volume;
The duration of remaining patent and regulatory exclusivity;
The number and strength of related patents;
Whether a generic can use a different ring architecture;
Manufacturing cost and availability of specialized silicone cores;
FDA acceptance of bioequivalence and in vitro release data;
The commercial discount required for a generic or follow-on product.

A successful Paragraph IV launch could reduce price and expand access, but a technically distinct ring might require a 505(b)(2) application rather than a conventional ANDA. That pathway could increase development time and regulatory cost.

Key Takeaways

US 11,529,308 is a combination patent for a reusable segesterone acetate/ethinyl estradiol vaginal ring.
Claim 1 requires a dual-channel silicone ring, two adhesive-fixed cylindrical cores, specified curing chemistry, drug loading, release rates and storage recovery.
The patent does not broadly claim segesterone acetate, ethinyl estradiol or all hormonal vaginal rings.
Claims 2 through 6 strengthen protection around adhesive quantity, surface coverage and drug allocation.
The patent presents its highest infringement risk to a substantially copied Annovera-type ring.
A competing product may pursue a design-around using a different core architecture, curing system, adhesive interface or drug-release profile.
FDA exclusivity and patent exclusivity are separate. The Orange Book and USPTO records control current listing and term analysis.
A Paragraph IV challenge would likely center on cumulative claim limitations, obviousness, indefiniteness, storage-performance proof and noninfringement.
The commercial patent risk cannot be assessed from US 11,529,308 alone. The full patent family, Orange Book listings and any later-filed continuation patents must be reviewed.

FAQs

Does US 11,529,308 cover all segesterone acetate contraceptive products?

No. It covers a defined reusable vaginal ring system with specified silicone, core, adhesive, drug-loading and release characteristics.

Can a generic avoid US 11,529,308 by changing only the amount of ethinyl estradiol?

Possibly, but not automatically. The product would need to fall outside the claim's drug amount or an associated limitation, and it would still need to avoid other patents in the product's patent family.

Is a single-core segesterone acetate ring likely to infringe claim 1?

A single-core ring would have a strong noninfringement position against the express two-channel, two-core limitations of claim 1. Other patents could still apply.

Does claim 6 require the hormones to be distributed between separate cores?

Yes. Claim 6 requires one core to contain segesterone acetate and the other core to contain both segesterone acetate and ethinyl estradiol.

Is a different silicone supplier enough to avoid infringement?

No. Supplier identity is not a claim limitation. The relevant issue is whether the finished ring and its pre-cure composition meet the claimed structural and chemical parameters.

References

United States Patent and Trademark Office. (2022). United States Patent No. 11,529,308, vaginal ring system. https://patents.google.com/patent/US11529308B2/en
U.S. Food and Drug Administration. (2018). FDA approves new vaginal ring for one year of birth control. https://www.fda.gov/news-events/press-announcements/fda-approves-new-vaginal-ring-one-year-birth-control
U.S. Food and Drug Administration. (n.d.). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/
U.S. Food and Drug Administration. (n.d.). Hatch-Waxman amendments and abbreviated new drug applications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/abbreviated-new-drug-application-anda-resources

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Mayne Pharma	ANNOVERA	ethinyl estradiol; segesterone acetate	RING;VAGINAL	209627-001	Aug 10, 2018		RX	Yes	Yes	11,529,308	⤷ Start Trial	Y				⤷ 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	120976	⤷ Start Trial
Australia	2020294780	⤷ Start Trial
Brazil	112021025853	⤷ Start Trial
Canada	3141077	⤷ Start Trial
Chile	2021003410	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 11,529,308

Which drugs does patent 11,529,308 protect, and when does it expire?

Summary for Patent: 11,529,308