Details for Patent: 11,951,213

Which drugs does patent 11,951,213 protect, and when does it expire?

Patent 11,951,213 protects DROSPIRENONE and SLYND and is included in two NDAs.

This patent has sixty-nine patent family members in thirty-one countries.

Summary for Patent: 11,951,213

Title:	Synthetic progestogens and pharmaceutical compositions comprising the same
Abstract:	Described herein are synthetic progestogens, such as 6β,7β:15β,16β-Dimethylene-3-oxo-17α-pregn-4-ene-21,17-carbolactone, as well as pharmaceutical compositions comprising the same. Also described are methods of use.
Inventor(s):	Philippe Perrin, Jose Luis Velada, Dominique Drouin
Assignee:	Laboratorios Leon Farma SA
Application Number:	US18/365,877
Patent Litigation and PTAB cases:	See patent lawsuits and PTAB cases for patent 11,951,213
Patent Claim Types: see list of patent claims	Use; Composition; Formulation;

US Patent 11,951,213: Claim Scope, Drospirenone Exclusivity, and Patent Landscape

US Patent No. 11,951,213 protects a specific drospirenone-only contraceptive regimen: 4 mg, or a broader 2-6 mg range, administered orally for 24 consecutive days followed by four days without dosing. The patent also covers contraceptive protection when up to two non-consecutive doses are delayed by as much as 24 hours. Its narrower claims target a controlled dissolution profile, suppression of progesterone, ovulation inhibition, reduced unscheduled bleeding, and the 4 mg commercial dose.

The patent is directed to drospirenone, the active ingredient in Slynd, marketed by Exeltis USA, Inc. Slynd contains 4 mg of drospirenone and uses a 24 active-tablet/4 placebo-tablet regimen.[1]

What drug and contraceptive regimen does US Patent 11,951,213 protect?

The chemical compound identified in the claims is drospirenone, also known by its systematic steroid name:

6β,7β:15β,16β-Dimethylene-3-oxo-17α-pregn-4-ene-21,17-carbolactone.

The patent protects a drospirenone-only oral contraceptive method with these core elements:

Limitation	Required scope
Patient	Female patient
Active ingredient	Drospirenone
Estrogen	Excluded
Dose	2-6 mg per daily dose
Commercially targeted dose	4.0 mg
Schedule	24 daily doses followed by 4 days without administration
Coverage period	28 days
Missed-dose flexibility	Up to two non-consecutive scheduled doses may be delayed up to 24 hours
Therapeutic result	Effective contraception
Additional claimed results	Ovulation inhibition and specified progesterone levels
Formulation feature	Controlled in vitro dissolution profile under USP XXIII Paddle Method

The independent claim is a method-of-treatment claim rather than a simple composition claim. A product containing drospirenone does not infringe claim 1 merely because it has the claimed ingredient and dose. The claimed administration schedule and contraceptive result must also be present.

How do claims 1 through 14 divide the patent scope?

Claim 1: Core 24/4 drospirenone regimen

Claim 1 is the principal method claim. It requires:

1. A female patient.
2. Oral administration.
3. A pharmaceutical composition containing 2-6 mg of drospirenone.
4. No estrogen in the composition.
5. Twenty-four scheduled daily doses within a 24-day period.
6. Four days without administration.
7. Effective contraception over the 28-day period.
8. Tolerance for up to two non-consecutive doses delayed by up to 24 hours.

This is a commercially significant claim because it maps closely to the Slynd dosing schedule and label instructions. The claim is broader than a claim limited to 4 mg, but narrower than a claim covering any drospirenone contraceptive regimen.

A competing product using 4 mg drospirenone with a 24/4 regimen would face the highest literal infringement exposure under claim 1 if its labeling instructs patients to use the same schedule and provides the same missed-dose flexibility.

Claims 2 and 12: Controlled dissolution formulation

Claim 2 adds a dissolution limitation:

• No more than 50% of the initially present drospirenone dissolves within 30 minutes.
• At least 50% dissolves between three and four hours.
• The test uses the USP XXIII Paddle Method.

Claim 12 further requires that at least 55% dissolve within four hours.

These claims do not cover every 4 mg drospirenone tablet. They require a particular release profile. The patent therefore separates the regimen protection from formulation-specific protection.

The dissolution claims may be important in an ANDA dispute because the relevant evidence would include:

• Drug-release testing.
• Batch-specific dissolution data.
• The reference listed drug's release profile.
• Excipients and manufacturing parameters.
• The proposed generic's formulation and specifications.
• Whether the testing method is applied as required by the claim.

A generic applicant could attempt to design around claims 2 and 12 by using a materially different release profile while retaining the 24/4 regimen. That strategy would not, by itself, avoid claim 1.

Claims 3 and 4: Progesterone suppression

Claim 3 requires progesterone below 5.04 ng/mL throughout the 28-day period. Claim 4 narrows the threshold to 3 ng/mL or lower.

These claims create a biological-performance limitation. They are narrower and more difficult to enforce than claim 1 because infringement may depend on clinical or pharmacodynamic evidence in the treated patient population.

Issues likely to arise include:

• The timing and number of progesterone measurements.
• The assay used.
• Whether "during the entire 28-day period" requires continuous measurement or representative measurements.
• Patient adherence.
• Baseline hormonal status.
• Interpatient variation.
• Whether the result is inherent in the regimen or must be demonstrated for the accused product.

The claims may provide additional protection against a formulation that uses the same nominal dose but produces materially different exposure or hormonal suppression.

Claims 5 through 8: Delayed and catch-up doses

Claims 5-8 cover one or two delayed, non-consecutive scheduled doses. They require that the relevant dose be delayed by up to 24 hours and that the patient receive two doses within 24 hours from the scheduled administration time.

These claims are commercially important because missed-dose instructions are a central feature of a contraceptive label. Claims 5 and 6 address one delayed dose. Claims 7 and 8 address two delayed, non-consecutive doses.

The claims do not appear to cover:

• Two consecutive missed doses.
• Delays longer than 24 hours.
• An indefinite failure to take the dose.
• Any dosing schedule outside the 24/4 regimen of claim 1.
• A composition containing estrogen.

The "non-consecutive" limitation creates a potential design-around and claim-construction issue. A regimen involving two consecutive late doses would not literally satisfy claims 1, 7, or 8 as written, although the remaining limitations could still create risk under other claims or legal theories.

Claims 9 through 11: Ovulation and bleeding outcomes

Claim 9 requires ovulation inhibition.

Claims 10 and 11 apply the dissolution profile from claim 2 and add an improved bleeding profile compared with a progestogen-only composition without that profile. Claim 11 identifies reduced unscheduled spotting and/or bleeding as the improvement.

These claims are narrower than claim 1 and introduce comparative clinical-performance requirements. To establish infringement, a patent owner would likely need to show:

• The accused formulation has the claimed dissolution profile.
• The patient is treated under the claimed 24/4 regimen.
• The bleeding profile is improved against the relevant comparator.
• The improvement is linked to the dissolution profile rather than unrelated patient or study factors.

Claims 13 and 14: 4 mg commercial dose

Claim 13 requires 4.0 mg of drospirenone. Claim 14 requires 3.5-4.5 mg.

These claims are the most directly aligned with Slynd's marketed dose. Claim 13 is narrower than claim 14 but potentially easier to apply to a product labeled specifically as containing 4 mg.

What is the likely infringement exposure for a generic drospirenone product?

A generic product would face different risks depending on its label and formulation.

Generic design	Claim 1 risk	Claims 2/12 risk	Missed-dose claims	Overall exposure
4 mg drospirenone, 24/4 schedule, same missed-dose instructions	High	Depends on dissolution	High	High
4 mg drospirenone, 24/4 schedule, altered dissolution profile	High	Potentially reduced	High	High
4 mg drospirenone, different dosing schedule	Potentially reduced	Depends on use	Reduced	Product-specific
Drospirenone-only tablet with no estrogen but no contraceptive indication	Reduced label-based risk	Formulation dependent	Reduced	Still subject to induced-use analysis
Drospirenone plus estrogen	Outside the literal "does not comprise estrogen" limitation	Usually outside these claims	Outside core scope	Lower under these claims
Dose below 2 mg or above 6 mg	Outside claim 1	Other claims may differ	Outside core scope	Lower under these claims
Two consecutive delayed doses	Outside the express non-consecutive limitation	Other limitations remain	Reduced for claims 7-8	Partial design-around

A skinny-label strategy could remove certain method-of-use instructions, such as delayed-dose protection or bleeding-profile language. It would not automatically eliminate risk if the remaining label still instructs the 24/4 drospirenone regimen covered by claim 1.

For method claims, induced infringement can become important. A manufacturer may face exposure if its labeling, promotional material, patient instructions, or other conduct encourages the patented administration method. The fact that patients perform the dosing does not eliminate potential manufacturer liability.

What formulation is protected by the patent?

The patent does not claim a generic controlled-release tablet in abstract terms. It claims a drospirenone composition having a defined dissolution pattern under a specified test.

The practical formulation target is a tablet in which drospirenone is not released too quickly. The required profile has two principal features:

Time point	Required dissolution result
30 minutes	No more than 50% dissolved
3-4 hours	At least 50% dissolved
By 4 hours under claim 12	At least 55% dissolved

This profile may implicate:

• Particle size.
• Solid-state form.
• Wetting characteristics.
• Tablet hardness.
• Disintegrants and binders.
• Coating or matrix technology.
• Manufacturing compression conditions.
• Excipients affecting dissolution.

The claims are not limited to a particular excipient list in the text supplied. That gives the formulation claims functional breadth, but it also creates potential validity and proof issues. The patent owner would need to establish that the accused product satisfies the numerical release criteria under the required method.

How strong is the patent estate for Slynd and drospirenone-only contraception?

US Patent 11,951,213 is strongest when viewed as one layer of protection around a branded 4 mg drospirenone-only product.

Strengths

• It targets the commercially used 24/4 regimen.
• It covers the marketed 4 mg dose through claims 13 and 14.
• It addresses delayed doses, an important patient-use feature.
• It combines composition, regimen, and clinical-result limitations.
• It includes a formulation profile that may be difficult to replicate accidentally.
• It can create litigation leverage even if a generic attempts to modify its label.

Limitations

• The independent claim is a method claim, not a broad composition claim.
• Claim 1 requires the absence of estrogen.
• Claim 1 requires the 24/4 schedule.
• The delayed doses must be non-consecutive and no more than 24 hours late.
• Claims 2, 10, 11, and 12 depend on a specific dissolution profile.
• Claims 3 and 4 depend on progesterone measurements.
• Claims 10 and 11 require a comparative bleeding benefit.
• The patent does not prevent all drospirenone products, all progestin-only contraceptives, or all alternative dosing schedules.

The estate is therefore commercially meaningful but concentrated. It is strongest against a conventional generic intended to reproduce Slynd's 4 mg, 24/4 product and labeling.

What is the Orange Book status of US Patent 11,951,213?

Slynd is approved under FDA NDA 214154 as a drospirenone-only oral contraceptive.[1] The FDA Orange Book can list patents associated with an approved drug product, including formulation and method-of-use patents.[2]

A patent's existence does not establish that it is listed in the Orange Book. Listing depends on the NDA holder's submission and FDA acceptance under the applicable Orange Book regulations. The critical commercial questions are:

• Whether US 11,951,213 is listed against NDA 214154.
• Whether the listing is for drug substance, drug product, or method of use.
• Whether the listing covers the approved 4 mg tablet.
• Whether a generic applicant must make a Paragraph IV certification.
• Whether the listed patent remains active when an ANDA is filed.

If listed, an ANDA applicant asserting that the patent is invalid, unenforceable, or not infringed could trigger the Hatch-Waxman litigation framework. A timely Paragraph IV notice may produce a 30-month stay of approval under the statutory conditions.[3]

When does US Patent 11,951,213 lose exclusivity?

The patent's enforceable term is generally based on 20 years from the earliest effective nonprovisional filing date, subject to patent-term adjustment, terminal disclaimers, and any applicable patent-term extension.[4]

The issue date alone does not determine expiration. US Patent 11,951,213 was issued in 2024, but its expiration date must be calculated from the patent's priority and filing history rather than from the issue date. Patent-term adjustment can extend the base term, while a terminal disclaimer can limit it to the term of another patent.

Regulatory exclusivity is separate from patent exclusivity. Slynd received FDA approval in 2019. Any new chemical entity exclusivity associated with that approval would have run separately from patent protection and would not replace the patent analysis.[1]

Are Paragraph IV challenges and generic entry likely?

A generic applicant seeking approval for 4 mg drospirenone tablets could challenge the patent through a Paragraph IV certification if the patent is listed against the reference drug.

The most likely challenge positions would include:

1. Noninfringement because the generic label omits delayed-dose or bleeding-profile instructions.
2. Noninfringement because the product does not meet the claimed dissolution profile.
3. Invalidity based on anticipation or obviousness.
4. Indefiniteness of functional or comparative limitations.
5. Lack of written description or enablement for the full claimed numerical ranges.
6. Lack of infringement because the method is not practiced as labeled.
7. Invalidity or noninfringement based on the "non-consecutive" delayed-dose limitation.

The principal generic launch scenarios are:

Scenario	Commercial effect
No Paragraph IV challenge	Launch delayed until patent expiry or other resolution
Paragraph IV with litigation	Potential 30-month approval stay
Settlement with delayed entry	Entry date governed by agreement and regulatory review
Successful invalidity or noninfringement decision	Earlier launch possible
Skinny-label approval	Entry limited to non-patented uses and instructions
Formulation design-around	May avoid dissolution claims but not necessarily claim 1

No settlement agreement, licensing transaction, or litigation outcome is established by the claim text itself. Those matters must be evaluated from FDA records, court dockets, and SEC or company disclosures rather than inferred from the patent claims.

Does biosimilar risk apply to Slynd?

No. Slynd contains drospirenone, a chemically synthesized small-molecule active ingredient. The relevant competitive pathway is an ANDA for a generic drug, not a biosimilar application under the Biologics Price Competition and Innovation Act.

The principal entry barriers are:

• Orange Book-listed patents.
• Bioequivalence requirements.
• Formulation similarity.
• Labeling and method-of-use issues.
• Paragraph IV litigation.
• Manufacturing and dissolution specifications.

There is no conventional biosimilar interchangeability analysis for drospirenone.

How does this patent compare with competing contraceptive patent estates?

Product category	Typical active ingredient	Main protection type	Relevance to US 11,951,213
Slynd	Drospirenone	24/4 regimen, formulation, method of use	Directly covered
Norethindrone progestin-only pills	Norethindrone	Product and regimen patents vary	Outside drospirenone-specific claims
Combined oral contraceptives	Estrogen plus progestin	Combination, formulation, use patents	Generally outside claim 1 because estrogen is excluded
Long-acting implants	Etonogestrel or levonorgestrel	Device and delivery patents	Outside oral-dose claims
Injectable contraceptives	Medroxyprogesterone acetate	Formulation and administration patents	Outside the claimed oral regimen
Drospirenone combination products	Drospirenone plus estrogen	Combination-product patents	Potentially outside the no-estrogen limitation

The patent is not a general contraceptive patent. Its competitive relevance is concentrated in oral drospirenone-only products that copy the approved Slynd regimen.

What manufacturing and geographic barriers does the patent create?

The patent is enforceable only in the jurisdictions where corresponding rights exist. US 11,951,213 does not independently block manufacture or sale outside the United States.

For US commercial entry, a competing manufacturer may need to address:

• The active ingredient's quality and regulatory specifications.
• Tablet dissolution performance.
• Bioequivalence to the reference product.
• The 24/4 regimen in labeling.
• Manufacturing-process consistency.
• Patent certifications and litigation.
• Importation into the United States.

Manufacturing outside the United States does not eliminate US infringement risk if the product is imported, offered for sale, sold, or used in the United States. Process and formulation changes may reduce risk under claims 2 and 12, but they do not necessarily avoid the broader regimen claim.

Key Takeaways

• US Patent 11,951,213 is a drospirenone-only contraceptive method patent closely aligned with Slynd.
• Claim 1 covers 2-6 mg drospirenone, a 24/4 schedule, no estrogen, and protection despite up to two non-consecutive doses delayed by 24 hours.
• Claims 13 and 14 target the commercial 4 mg dose.
• Claims 2 and 12 protect a controlled dissolution profile rather than every drospirenone tablet.
• Claims 3 and 4 add progesterone thresholds below 5.04 ng/mL and 3 ng/mL.
• Claims 10 and 11 address improved bleeding and reduced unscheduled spotting or bleeding.
• The patent is strongest against a generic copying the 4 mg Slynd formulation, label, and 24/4 regimen.
• A formulation design-around may reduce risk under the dissolution claims but will not automatically avoid claim 1.
• Generic entry would likely proceed through the ANDA pathway, with Paragraph IV certification if the patent is listed in the Orange Book.
• Biosimilar law is not relevant because drospirenone is a small-molecule drug.
• Patent expiration must be calculated from the patent family’s effective filing history, with adjustments for patent-term adjustment, terminal disclaimers, and any applicable extension.

FAQs About US Patent 11,951,213

Is US Patent 11,951,213 a composition patent?

No. The supplied claims are primarily method-of-treatment claims. They require administering a drospirenone composition under a specified contraceptive schedule.

Does the patent cover all drospirenone birth-control products?

No. It is limited by dose, oral administration, the 24/4 schedule, absence of estrogen, and effective contraception. Products using estrogen, other dosing schedules, or different doses may fall outside claim 1.

Can a generic avoid the patent by changing the dissolution profile?

Changing the dissolution profile may reduce exposure under claims 2, 10, 11, and 12. It does not necessarily avoid claim 1, which does not expressly require the claimed dissolution profile.

Does a delayed dose have to be non-consecutive?

Yes. Claims 1 and 5-8 expressly address non-consecutive delayed doses. Two consecutive delayed doses present a different claim-analysis issue.

Is a Paragraph IV challenge required for every drospirenone generic?

Only if the relevant patent is listed in the Orange Book and the generic applicant makes a certification addressing that listing. A patent's existence alone does not establish a Paragraph IV obligation.

References

1. U.S. Food and Drug Administration. (2019). Slynd (drospirenone) tablets prescribing information. NDA 214154.

2. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book.

3. 21 U.S.C. § 355(j).

4. 35 U.S.C. §§ 154, 156, 253.

5. United States Patent and Trademark Office. (2024). U.S. Patent No. 11,951,213.

Drugs Protected by US Patent 11,951,213

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Patented / Exclusive Use	Submissiondate
Exeltis Usa Inc	DROSPIRENONE	drospirenone	TABLET, CHEWABLE;ORAL	216285-001	Jun 29, 2022		DISCN	Yes	No	11,951,213					PREVENTION OF PREGNANCY IN FEMALES OF REPRODUCTIVE AGE
Exeltis Usa Inc	SLYND	drospirenone	TABLET;ORAL	211367-001	May 23, 2019		RX	Yes	Yes	11,951,213					PREVENTION OF PREGNANCY IN FEMALES OF REPRODUCTIVE AGE

International Family Members for US Patent 11,951,213

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
European Patent Office	2588114		CA 2020 00023	Denmark
European Patent Office	2588114		2020C/518	Belgium
European Patent Office	2588114		19/2020	Austria
European Patent Office	2588114		C202030026	Spain
European Patent Office	2588114		301123	Netherlands
European Patent Office	2588114		PA2021523	Lithuania
European Patent Office	2588114		LUC00227	Luxembourg