When will the AYGESTIN patents expire, and when will generic AYGESTIN be available?

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Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Duramed Res	AYGESTIN	norethindrone acetate	TABLET;ORAL	018405-001	Apr 21, 1982		DISCN	Yes	No	⤷ Start Trial	⤷ Start Trial				⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>TE	>Type	>RLD	>RS	>Patent No.	>Patent Expiration	>Product	>Substance	>Delist Req.	>Exclusivity Expiration

Last updated: August 1, 2026

Aygestin is the branded 5 mg norethindrone acetate tablet used for secondary amenorrhea, endometriosis, and abnormal uterine bleeding caused by hormonal imbalance. Its commercial profile is mature and largely genericized. The investment case is therefore tied to portfolio ownership, manufacturing economics, distribution, and women’s-health strategy rather than to a durable Aygestin patent moat.

What is Aygestin and how does it work?

Aygestin contains norethindrone acetate, a synthetic progestin. The drug is administered orally and is approved in the United States for:

Secondary amenorrhea
Endometriosis
Abnormal uterine bleeding caused by hormonal imbalance in the absence of organic pathology

The product is not approved as a contraceptive at the 5 mg Aygestin dosage. Norethindrone acetate is converted in the body to norethindrone, which produces progestational effects on the endometrium and suppresses estrogen-driven endometrial proliferation. The FDA label identifies dosage regimens that vary by indication, with treatment commonly administered for limited periods or in cyclic schedules. (U.S. Food and Drug Administration [FDA], 2023)

What is the active ingredient in Aygestin?

Product	Active ingredient	Strength	Dosage form	Main U.S. uses
Aygestin	Norethindrone acetate	5 mg	Oral tablet	Amenorrhea, endometriosis, abnormal uterine bleeding
Generic equivalents	Norethindrone acetate	5 mg	Oral tablet	Same or substantially equivalent indications

Aygestin should be distinguished from lower-dose norethindrone products marketed for contraception. The active moiety is related, but the products have different dosage strengths, labeling, and clinical uses.

What is the FDA regulatory status of Aygestin?

Aygestin is an FDA-approved prescription drug with a mature regulatory history. The product is associated with an original new drug application and has generic equivalents approved through abbreviated new drug applications.

Regulatory factor	Assessment
FDA status	Approved prescription drug
FDA pathway	Original NDA for the branded product; ANDAs for generic equivalents
Active ingredient	Norethindrone acetate
U.S. strength analyzed	5 mg
Biosimilar exposure	None
Generic exposure	High
Regulatory novelty	Low
Current commercial position	Mature branded/generic product

The principal regulatory risk is not clinical development failure. It is substitution by lower-priced generic products, changes in reimbursement, and possible manufacturer or supply-chain disruption.

What patents protect Aygestin?

Aygestin does not present a meaningful current composition-of-matter patent opportunity. Norethindrone acetate is an established small molecule, and the product has been marketed for decades. Any original compound or early formulation patents would have expired long ago.

Are Aygestin formulation patents still relevant?

The commercial value of formulation patents is limited unless they cover a differentiated product, such as:

Extended release
A new route of administration
A combination product
A clinically meaningful dosing advantage
A formulation with demonstrated superiority or reduced toxicity

The standard Aygestin 5 mg tablet does not have an evident current patent barrier that would prevent generic substitution. Patent protection should be assessed through the FDA Orange Book and relevant patent databases for the specific NDA and manufacturer. The Orange Book is the controlling source for patents listed by an NDA holder for FDA-approved products. (FDA, 2024a)

Are method-of-use patents important for Aygestin?

Method-of-use patents could theoretically cover a specific patient population, regimen, or indication. In practice, such patents would face limited commercial value for a mature oral progestin unless they provide a meaningful clinical distinction over existing generic use.

The approved indications are established and clinically familiar. A new method-of-use patent would need to support a differentiated commercial strategy, such as a defined endometriosis population or a dosing regimen with clear safety or efficacy benefits.

When does Aygestin lose exclusivity?

Aygestin’s practical exclusivity has already ended. The product is exposed to generic competition, and the relevant investment question is not when exclusivity expires but whether any remaining brand, supply, or channel advantages can produce sustainable margins.

Exclusivity category	Current assessment
New chemical entity exclusivity	Expired
Original patent exclusivity	Expired
Orphan-drug exclusivity	Not a core Aygestin protection
Pediatric exclusivity	No current commercial significance
Generic competition	Established
Biosimilar exclusivity	Not applicable

Generic products approved under section 505(j) of the Federal Food, Drug, and Cosmetic Act can rely on the reference product’s safety and efficacy findings, subject to bioequivalence and applicable regulatory requirements. (FDA, 2024b)

How many patents cover Aygestin?

The number of historically associated patents is less important than the number of enforceable, commercially relevant patents remaining today. For the standard norethindrone acetate 5 mg tablet, the practical answer is that there is no clear active patent estate creating a durable barrier to generic competition.

A diligence review should separate:

Expired composition patents.
Expired manufacturing patents.
Expired formulation patents.
Patents listed for the specific NDA.
Patents covering unrelated norethindrone products.
Patents covering new formulations or combination products rather than Aygestin itself.

Patent-count databases can overstate protection by including expired documents, foreign family members, abandoned applications, or patents covering different dosage forms.

What generic entry risks exist for Aygestin?

Generic entry risk is high because the product has the main characteristics associated with commodity pharmaceutical competition:

Long commercial history
Simple oral tablet formulation
Established active ingredient
No biologic manufacturing complexity
No refrigeration requirement in the standard product
Multiple potential generic manufacturers
Limited switching friction
Mature prescriber familiarity

Generic competition can reduce both price and prescription volume for the branded product. Pharmacy substitution is particularly important for oral tablets because patients and prescribers often have limited ability to prevent substitution when the generic is therapeutically equivalent.

What manufacturing and intellectual-property barriers exist?

Manufacturing barriers are modest. Norethindrone acetate tablets require standard solid-dose manufacturing capabilities, including blending, compression, coating or finishing where applicable, packaging, and quality testing.

Potential barriers include:

FDA inspection readiness
Reliable active pharmaceutical ingredient supply
Content uniformity and dissolution performance
Stability and packaging compliance
Quality-system maintenance
Ability to secure commercial-scale distribution

These barriers can create temporary supply advantages, but they do not equal patent protection. A manufacturer with a strong supply record may retain customers during shortages, while a manufacturer dependent on a single API source may face margin and availability pressure.

What is the commercial market for Aygestin?

Aygestin participates in several established women’s-health markets:

Abnormal uterine bleeding
Secondary amenorrhea
Endometriosis
Progestin therapy in selected hormonal disorders

The drug is generally prescribed for lower-volume, indication-specific use rather than chronic high-volume primary-care treatment. Endometriosis can support recurring treatment demand, but clinicians also use other hormonal therapies, including combined oral contraceptives, progestin-only products, gonadotropin-releasing hormone therapies, and newer oral agents.

The market is commercially fragmented. Revenue is likely distributed across branded products, authorized generics, standard generics, wholesalers, and retail or specialty channels. Public companies generally do not report Aygestin revenue as a separate product line. Any claim of product-level sales should therefore be supported by prescription audits, IQVIA data, Symphony Health data, or manufacturer disclosures.

How strong is the Aygestin patent estate?

The patent estate is weak from an investment perspective.

Patent-strength factor	Rating	Analysis
Composition-of-matter protection	Very weak	Legacy small-molecule protection is expired
Formulation protection	Weak	Standard tablet has limited apparent differentiation
Method-of-use protection	Weak to moderate	Possible narrow claims, but limited commercial leverage
Manufacturing protection	Weak	Conventional oral solid-dose process
Regulatory exclusivity	Weak	Generic approvals are established
Brand recognition	Moderate	Historical name recognition may support demand
Switching barriers	Low	Generic substitution is straightforward
Overall moat	Weak	Economics depend on execution and portfolio position

Brand recognition may provide some residual value in prescriber or patient familiarity, but it is unlikely to offset sustained generic price competition without a differentiated commercial channel or supply advantage.

Which companies are challenging Aygestin?

The relevant challengers are generic manufacturers rather than branded pharmaceutical innovators. Generic competition can include established U.S. suppliers and contract manufacturers operating through ANDA approvals, wholesaler relationships, and retail pharmacy distribution.

The competitive set may change over time because manufacturers can enter or exit based on pricing, API costs, FDA compliance, and market size. A definitive current list should be taken from the FDA Orange Book and Drugs@FDA records for the relevant reference product and strength. (FDA, 2024a; FDA, 2024c)

The most important competitive variables are:

Number of active ANDA suppliers
Wholesale acquisition cost
Retail availability
Back-order frequency
FDA warning letters or manufacturing restrictions
API sourcing concentration
Pharmacy substitution rates

What is the Orange Book status of Aygestin?

The Orange Book identifies approved drug products and, where applicable, patent and exclusivity information. For Aygestin, the commercial significance of Orange Book protection is limited because the product has long been exposed to generic competition.

The key diligence items are:

Orange Book question	Investment implication
Is the reference listed drug active?	Determines the regulatory reference product
Are patents listed?	Indicates potential ANDA certification issues
Are exclusivity codes present?	Determines whether regulatory blocking periods remain
How many ANDAs are approved?	Indicates competitive intensity
Are all approved strengths commercially supplied?	Indicates real rather than nominal competition

An approved ANDA does not guarantee active commercial supply. Some listed manufacturers may not market continuously, particularly in low-margin products.

Are there Paragraph IV challenges involving Aygestin?

Paragraph IV litigation is not the central investment issue for a mature norethindrone acetate tablet. Paragraph IV certifications arise when an ANDA applicant asserts that a listed patent is invalid, unenforceable, or will not be infringed. If no relevant unexpired Orange Book patent remains, ordinary generic approval and substitution economics matter more than patent litigation.

A diligence review should examine FDA patent-listing data and federal court records for any current case involving the specific Aygestin NDA, dosage form, and strength. Historical litigation involving other norethindrone products should not be attributed to Aygestin without matching the NDA and patent claims.

What patent litigation affects Aygestin?

There is no evident current litigation issue that creates a material standalone investment thesis for standard Aygestin 5 mg tablets. The more relevant legal risks are routine pharmaceutical-commercial matters:

Product liability claims
Manufacturing and quality disputes
Trademark ownership or brand-use disputes
Supply agreements
Distribution contracts
Promotional compliance
Generic substitution disputes

These issues are generally less valuable to an investor than verified information on current net pricing, volume, supplier concentration, and gross margin.

What licensing deals are connected to Aygestin?

Aygestin is not generally viewed as a licensing-driven growth asset. A licensing transaction involving the product would most likely concern:

Brand rights in a specific territory
Generic distribution rights
An authorized-generic arrangement
Women’s-health portfolio consolidation
Manufacturing or supply rights

The financial value of such a deal would depend on transfer price, territory, remaining brand demand, manufacturing cost, promotional obligations, and channel access. Without a disclosed transaction, Aygestin should not be assigned strategic licensing value comparable to a patented specialty drug.

What are the main investment scenarios for Aygestin?

Base case: stable mature-product cash flow

A portfolio owner continues supplying Aygestin or an equivalent product through established channels. Revenue remains stable or declines gradually, while margins reflect generic pricing and manufacturing costs. This is the most defensible base case.

Upside case: supply scarcity or portfolio optimization

An owner gains share through competitor shortages, manufacturing exits, improved wholesaler access, or consolidation of women’s-health products. The upside would likely be temporary unless the company secures durable cost or distribution advantages.

Downside case: accelerated commoditization

Additional generic suppliers, lower reimbursement, API inflation, or manufacturing problems reduce price and volume. Brand-only sales could contract faster than the broader norethindrone acetate market.

Strategic case: reformulation or lifecycle extension

A company could develop a differentiated formulation, combination product, or new delivery system. That would create a separate regulatory and patent asset, but it would no longer represent the current Aygestin tablet alone. The commercial case would depend on clinical differentiation and payer acceptance.

How does Aygestin compare with competing hormonal treatments?

Therapy	Commercial profile	Patent position	Main competitive advantage
Aygestin/norethindrone acetate	Mature oral progestin	Weak	Familiarity and low-cost access
Combined oral contraceptives	Large generic market	Generally mature	Contraception plus cycle control
Progestin-only contraceptives	Generic and branded products	Mixed	Contraceptive positioning
Levonorgestrel intrauterine systems	Device-based, branded/generic competition	Product-specific	Long duration and local delivery
GnRH antagonists	Specialty branded market	Stronger for newer products	Endometriosis symptom control and differentiated mechanisms
Depot progestins	Established injectable market	Mature	Longer dosing interval

Aygestin’s advantage is low complexity and broad clinician familiarity. Its disadvantage is the lack of exclusivity and limited differentiation.

What is the revenue exposure for an Aygestin owner?

Product-level revenue exposure should be evaluated through a five-part model:

Prescription volume by indication.
Net price after rebates and discounts.
Branded versus generic mix.
Manufacturing cost and API expense.
Share of revenue from the broader women’s-health portfolio.

Because Aygestin is rarely reported separately, investors should avoid treating total women’s-health revenue as Aygestin revenue. A material valuation conclusion requires verified product sales, contribution margin, and channel data.

Key Takeaways

Aygestin is a mature 5 mg norethindrone acetate tablet.
Its FDA-approved uses include secondary amenorrhea, endometriosis, and abnormal uterine bleeding.
Original patent and regulatory exclusivity are no longer meaningful commercial protections.
Generic substitution risk is high.
The standard tablet has limited apparent formulation or manufacturing differentiation.
There is no biosimilar risk because Aygestin is a small-molecule drug.
The investment case depends on supply reliability, distribution, pricing, and portfolio strategy.
Product-level revenue is generally not disclosed by public companies.
A new formulation or combination product could create a separate lifecycle-management opportunity, but it would require new clinical, regulatory, and patent analysis.
Aygestin is better viewed as a mature cash-flow or portfolio asset than as a standalone growth drug.

FAQs About Aygestin Investment and Patent Risk

Is Aygestin still under patent protection?

The standard Aygestin 5 mg tablet does not appear to have commercially meaningful original patent protection remaining. Current protection should be checked against the applicable FDA Orange Book listing.

Can generic companies automatically substitute norethindrone acetate for Aygestin?

Approved generic norethindrone acetate tablets may generally be substituted under applicable state pharmacy laws and payer policies, subject to the product’s therapeutic-equivalence designation and prescription requirements.

Is Aygestin a contraceptive investment opportunity?

Aygestin itself is not positioned primarily as a contraceptive. Its investment value comes from treatment of menstrual and endometriosis-related conditions, while contraceptive norethindrone products represent a related but distinct market.

Does Aygestin have biosimilar competition?

No. Biosimilars apply to biological products. Aygestin is an orally administered small-molecule drug and faces generic, not biosimilar, competition.

Could a new Aygestin formulation regain exclusivity?

A reformulated or combination product could qualify for new patents and, depending on the regulatory pathway, new regulatory protections. The new product would need clinically meaningful differentiation to support pricing above standard generic norethindrone acetate.

References

U.S. Food and Drug Administration. (2023). Aygestin (norethindrone acetate) tablets, prescribing information. DailyMed.
U.S. Food and Drug Administration. (2024a). Approved drug products with therapeutic equivalence evaluations: Orange Book. https://www.fda.gov/drugs/drug-approvals-and-databases/approved-drug-products-therapeutic-equivalence-evaluations-orange-book
U.S. Food and Drug Administration. (2024b). Abbreviated new drug application (ANDA) process. https://www.fda.gov/drugs/types-applications/abbreviated-new-drug-application-anda
U.S. Food and Drug Administration. (2024c). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/

US Patents:	0
Applicants:	1
NDAs:	1

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