# United States Patent 11,504,334: Drospirenone Formulation Claims, Exclusivity, Litigation Risk, and Generic Entry

US Patent 11,504,334 protects selected oral pharmaceutical compositions containing micronized drospirenone, the active ingredient in Slynd. The patent does not claim drospirenone itself. Its principal coverage is a combination of particle size, estrogen-free composition, dissolution behavior, and fasting pharmacokinetic performance. The patent is strongest against products that reproduce the Slynd formulation and its release profile, but its functional claim limitations create potential infringement and validity disputes.

The patent’s nominal expiration date is December 18, 2035, subject to any patent-term adjustment, terminal disclaimer, or regulatory patent-term extension reflected in official records. Slynd received FDA approval in 2019 as a 4-mg drospirenone-only oral contraceptive. [1][2]

What does US Patent 11,504,334 protect?

The patent protects a pharmaceutical composition containing particles of drospirenone with a diameter below 10 micrometers, one or more pharmaceutically acceptable excipients, and no estrogen. The composition must also satisfy both pharmacokinetic and dissolution requirements.

Core limitation	Requirement in claim 1
Active ingredient	6β,7β:15β,16β-dimethylene-3-oxo-17α-pregn-4-ene-21,17-carbolactone, commonly known as drospirenone
Particle size	Particles have a diameter less than 10 μm
Composition	One or more pharmaceutically acceptable excipients
Estrogen	Composition does not comprise estrogen
Fasting Tmax	Mean Tmax from 2.2 to 6 hours
Fasting Cmax	Mean Cmax below 30 ng/mL
Early dissolution	No more than 50% dissolved within 30 minutes
Dosage form	Not required by claim 1; dependent claims cover tablets and capsules

The claim is a composition claim, but several limitations describe the behavior of the finished product in human pharmacokinetic testing and in vitro dissolution testing. A competing product would generally need to satisfy every limitation of an asserted claim to be found literally infringing.

How broad is the independent claim?

Claim 1 is narrower than a conventional active-ingredient or formulation claim because it requires a defined combination of structural and performance attributes.

The particle-size limitation requires the presence of drospirenone particles below 10 μm. The claim does not expressly state whether “diameter” means average diameter, median diameter, D90, or that every particle must fall below 10 μm. That issue could affect both infringement testing and validity analysis.

The no-estrogen limitation excludes combined oral contraceptive products containing ethinyl estradiol or another estrogen. The claim is directed to a progestin-only product.

The PK limitations require a fasting mean Tmax between 2.2 and 6 hours and a fasting mean Cmax below 30 ng/mL. These are population-level limitations, not necessarily single-patient requirements. The patent does not appear, from the quoted claims, to define the number of subjects, sampling schedule, statistical treatment, or acceptable variability.

The dissolution limitation is also material. No more than 50% of the initially present drospirenone may dissolve within 30 minutes under a USP XXIII Paddle Method test. The quoted claim does not specify the paddle rotation speed, dissolution medium, volume, temperature, pH, apparatus configuration, or sampling correction. Those parameters can become significant in an infringement or validity dispute.

What dependent claims add to the patent estate?

The dependent claims create multiple fallback positions around the core formulation.

What excipients are covered?

Claims 2 through 11 cover common oral-tablet excipient classes:

Excipient class	Examples identified in the claims
Fillers	Lactose, microcrystalline cellulose, starch, pregelatinized starch, calcium phosphate, calcium carbonate, mannitol, sorbitol
Lubricants	Magnesium stearate, calcium stearate, talc, stearic acid, mineral oil, sodium lauryl sulfate
Binders	Starch, gums, gelatin, microcrystalline cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, povidone
Glidants	Silicon dioxide, magnesium trisilicate, powdered cellulose, starch, talc, tribasic calcium phosphate

These claims cover broad functional categories and long lists of conventional excipients. Their commercial value is highest when combined with the active-ingredient, particle-size, dissolution, and PK limitations inherited from claim 1.

What dosage forms and coatings are protected?

Claim 12 covers tablets and capsules. Claim 13 adds a coating, and claim 14 identifies hydroxypropylmethyl cellulose, hydroxypropyl cellulose, and ethyl cellulose as coating materials.

The coating claims do not independently protect every coated drospirenone tablet. They depend on the requirements of claim 1, including the particle-size, estrogen-exclusion, PK, and dissolution limitations.

What dosage strengths are covered?

Claims 16 through 19 cover drospirenone quantities from 2 mg to 6 mg, with narrower claims directed to:

3.0 mg to 4.5 mg;
3.5 mg; and
4.0 mg.

The 4.0-mg claims align directly with the FDA-approved Slynd strength. Claims 25 through 30 combine the 3.0-mg-to-4.5-mg range with selected dissolution, PK, or Cmax limitations.

What pharmacokinetic and dissolution profiles are claimed?

The patent claims a relatively controlled exposure profile rather than rapid dissolution.

Parameter	Broad claim requirement	Narrower dependent requirements
Mean Tmax, fasting	2.2 to 6 hours	No narrower Tmax range stated
Mean Cmax, fasting	Less than 30 ng/mL	15 to less than 30 ng/mL
AUC0 h-tlast	Not required in claim 1	At least 300 or 350 ng·h/mL
Dissolution at 30 minutes	No more than 50%	Same threshold
Dissolution at 4 hours	Not required in claim 1	At least 50% or 55%
Dose	Not required in claim 1	2 to 6 mg; 3.0 to 4.5 mg; 3.5 mg; 4.0 mg

The combination produces a delayed or controlled dissolution profile: relatively limited release during the first 30 minutes, followed by at least 50% or 55% dissolution by four hours in the narrower claims. This is different from a conventional immediate-release claim defined only by rapid dissolution.

The AUC claims are important because they prevent a potential design-around based on slowing dissolution so substantially that exposure falls below the claimed therapeutic range. Claims 21 and 22 require an AUC0 h-tlast of at least 300 or 350 ng·h/mL.

When does US Patent 11,504,334 lose exclusivity?

The patent’s nominal term is expected to run through December 18, 2035, based on the earliest claimed priority date publicly associated with the formulation family. [1] The enforceable expiration date should be determined from the USPTO patent record, including any patent-term adjustment and terminal disclaimer.

Milestone	Date or status
Earliest reported priority	December 18, 2015
US patent grant	November 22, 2022
Patent number	US 11,504,334 B2
Nominal 20-year term endpoint	December 18, 2035
FDA product associated with the formulation	Slynd, drospirenone 4 mg
Regulatory pathway	NDA approval
Biosimilar exclusivity	Not applicable

Patent expiration is separate from FDA regulatory exclusivity. Slynd is a small-molecule drug, so biosimilar rules do not apply. Generic applicants would use an ANDA, potentially with a Paragraph IV certification against listed patents.

What is the FDA and Orange Book status of Slynd?

The FDA approved Slynd, a drospirenone-only oral contraceptive, in 2019 under NDA 209909. The approved product contains 4 mg of drospirenone in an oral tablet and does not contain estrogen. [2]

The Orange Book is the relevant source for determining whether US Patent 11,504,334 is currently listed against the approved product and whether any use code or delisting event applies. The listing status can change through FDA updates, patent-holder submissions, litigation outcomes, or regulatory corrections. [3]

A listed formulation patent can require an ANDA applicant to certify that the patent is invalid, unenforceable, or will not be infringed. A Paragraph IV notice may trigger Hatch-Waxman litigation and a potential 30-month stay of approval under the statutory framework. [4]

Which companies are challenging US Patent 11,504,334?

No publicly established Paragraph IV challenger or final judgment against US Patent 11,504,334 is identified in the claim information provided. The absence of a reported challenge in the available record does not establish that the patent is unchallenged for its entire term.

The relevant competitive parties are:

Party	Role
Patent owner or formulation-family rights holder	Must be confirmed from the current USPTO assignment record
Exeltis or affiliated entities	Associated with Slynd commercialization and women’s-health products
FDA	Approved Slynd and maintains Orange Book records
ANDA applicants	Potential generic challengers
Generic manufacturers	Potential entrants after patent resolution or expiry

Patent ownership should be distinguished from product commercialization. The entity marketing Slynd, the NDA holder, the patent owner, and any licensee may be different legal entities.

What Paragraph IV risks exist for generic drospirenone?

A generic applicant could pursue several strategies.

Formulation replication

A 4-mg drospirenone tablet using sub-10-μm particles, conventional excipients, no estrogen, and a comparable dissolution profile would face the highest literal infringement risk. If the product also produces a fasting mean Cmax between 15 and 30 ng/mL, the narrower claims become relevant.

Dissolution design-around

A manufacturer could target more than 50% dissolution within 30 minutes or less than 50% dissolution after four hours. Each approach carries technical and regulatory risk. A materially faster product may fail bioequivalence or alter the approved release profile. A slower product may reduce exposure or fail the AUC requirements.

Particle-size design-around

Using drospirenone particles at or above 10 μm could avoid the express particle-size limitation. This design-around may affect dissolution, bioavailability, manufacturing uniformity, and bioequivalence.

PK design-around

A product could produce a mean Tmax outside the claimed range or a mean Cmax at or above 30 ng/mL. That strategy is difficult to control because PK results depend on formulation, food status, subject population, sampling design, and statistical analysis.

Estrogen-containing product

A product containing estrogen would not satisfy the “does not comprise estrogen” limitation. It would, however, be a different product category and would face separate regulatory and patent considerations.

How strong is the patent estate?

The patent is commercially meaningful but technically attackable.

Strengths

The claims align with a marketed 4-mg drospirenone-only product.
Claim 1 combines particle size, dissolution, and human PK limitations.
Dependent claims cover common dosage strengths and standard excipients.
The claimed profile may be difficult to avoid while maintaining bioequivalence.
The expected remaining term extends into 2035.

Vulnerabilities

The claim uses functional PK limitations that may be sensitive to study design.
“Diameter less than 10 μm” may require construction of the measurement method.
The quoted claims do not define key USP Paddle Method parameters.
Broad excipient lists may face written-description or obviousness challenges if the specification does not support the full genus.
Prior-art formulation work involving micronized drospirenone, controlled dissolution, and oral contraceptive tablets could be relevant.

The strongest claims are likely the combinations directed to 4 mg, 3.0 mg to 4.5 mg, sub-10-μm particles, delayed early dissolution, and the specified fasting PK profile. The excipient-only limitations add breadth but may contribute less independent exclusionary value because many listed excipients are routine.

What other patents affect the drospirenone landscape?

The relevant landscape has at least four layers:

Composition-of-matter patents for drospirenone and related steroid compounds.
Earlier combined oral contraceptive patents covering drospirenone with estrogen.
Formulation patents covering micronization, dissolution, bioavailability, and oral dosage forms.
Method-of-use patents covering contraception, premenstrual dysphoric disorder, acne, or related indications.

Older Bayer-originated drospirenone patents and combination-product patents are materially different from US 11,504,334 because this patent is directed to an estrogen-free formulation. Expired or expiring composition and combination patents may remove some barriers while leaving formulation patents enforceable.

Geographic protection is limited by jurisdiction. US 11,504,334 has no direct effect on generic entry in Europe, Canada, Japan, or other markets. Foreign family members must be reviewed separately for filing date, grant status, claim scope, opposition history, and term.

What manufacturing and IP barriers remain after patent expiry?

Patent expiry would not eliminate all entry barriers. A generic manufacturer would still need to demonstrate:

pharmaceutical-grade drospirenone sourcing;
particle-size control and batch uniformity;
reproducible dissolution;
bioequivalence under fasting conditions;
tablet compression and coating performance;
stability through the proposed shelf life;
compliance with FDA current good manufacturing practices; and
an ANDA that addresses all Orange Book-listed patents and exclusivity.

The formulation is therefore protected by both legal rights and execution requirements. Those manufacturing barriers are commercial, not substitutes for patent protection.

What licensing deals affect Slynd commercialization?

Slynd commercialization has involved Exeltis and affiliated women’s-health entities. Public product materials identify Exeltis USA in connection with Slynd. [2] A commercial license, distribution arrangement, or co-promotion agreement does not by itself establish ownership of US 11,504,334. Patent assignments and exclusive rights must be confirmed through USPTO assignment records and transaction filings.

No settlement agreement, authorized generic arrangement, or public license specifically resolving a Paragraph IV dispute involving US 11,504,334 is established by the quoted claims.

Key Takeaways

US 11,504,334 is a formulation patent, not a patent on drospirenone itself.
Claim 1 requires sub-10-μm drospirenone particles, no estrogen, specified fasting PK, and limited 30-minute dissolution.
Dependent claims cover 4-mg tablets, common excipients, coatings, AUC thresholds, and four-hour dissolution.
The expected nominal expiration date is December 18, 2035, subject to official term adjustments.
Slynd is an FDA-approved 4-mg drospirenone-only oral contraceptive.
A generic reproducing Slynd’s particle size and release profile would face meaningful Paragraph IV and infringement risk.
The principal legal vulnerabilities are claim construction, test-method definition, enablement, written description, obviousness, and reproducibility of the PK limitations.
Biosimilar risk does not apply because drospirenone is a small-molecule active ingredient.
No publicly established Paragraph IV litigation or settlement involving this patent is identified in the supplied record.

FAQs About US Patent 11,504,334

Is US Patent 11,504,334 a patent on Slynd?

It appears directed to the formulation characteristics associated with Slynd, including 4-mg drospirenone tablets, but it is not a composition-of-matter patent on drospirenone.

Can a generic use the same 4-mg drospirenone dose?

Yes. The dose alone is not the entire claim. A generic would need to assess the particle-size, dissolution, PK, estrogen, and other inherited limitations.

Does the patent cover drospirenone combined with estrogen?

No. Claim 1 expressly requires that the pharmaceutical composition not comprise estrogen.

Is US Patent 11,504,334 relevant to biosimilar litigation?

No. Biosimilars apply to biological products. Drospirenone products follow the small-molecule generic framework, principally through ANDA and Hatch-Waxman procedures.

What is the most important design-around opportunity?

The principal technical opportunities are changing the drospirenone particle-size distribution, altering the early dissolution profile, or producing a materially different fasting PK profile. Each approach must still satisfy FDA bioequivalence and product-quality requirements.

References

United States Patent and Trademark Office. (2022). US Patent No. 11,504,334, pharmaceutical composition comprising drospirenone. https://patents.google.com/patent/US11504334B2/en
U.S. Food and Drug Administration. (2019). Slynd: Drospirenone tablets, prescribing information and approval records. https://www.accessdata.fda.gov/
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.). Abbreviated new drug application approvals and patent certifications. https://www.fda.gov/drugs/abbreviated-new-drug-application-anda/abbreviated-new-drug-application-anda-forms-and-instructions

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	⤷ Start Trial	⤷ Start Trial	Y				⤷ Start Trial
Exeltis Usa Inc	SLYND	drospirenone	TABLET;ORAL	211367-001	May 23, 2019		RX	Yes	Yes	⤷ Start Trial	⤷ 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
European Patent Office	2588114	⤷ Start Trial	CA 2020 00023	Denmark	⤷ Start Trial
European Patent Office	2588114	⤷ Start Trial	2020C/518	Belgium	⤷ Start Trial
European Patent Office	2588114	⤷ Start Trial	19/2020	Austria	⤷ Start Trial
European Patent Office	2588114	⤷ Start Trial	C202030026	Spain	⤷ Start Trial
>Country	>Patent Number	>Estimated Expiration	>Supplementary Protection Certificate	>SPC Country	>SPC Expiration

Details for Patent: 11,504,334

Which drugs does patent 11,504,334 protect, and when does it expire?

Summary for Patent: 11,504,334