Drugs in MeSH Category Menstruation-Inducing Agents

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Corcept Therap	KORLYM	mifepristone	TABLET;ORAL	202107-001	Feb 17, 2012	AB	RX	Yes	Yes	10,195,214
Corcept Therap	KORLYM	mifepristone	TABLET;ORAL	202107-001	Feb 17, 2012	AB	RX	Yes	Yes	10,780,097
Corcept Therap	KORLYM	mifepristone	TABLET;ORAL	202107-001	Feb 17, 2012	AB	RX	Yes	Yes	10,166,242

Menstruation-Inducing Agents Market Dynamics and Patent Landscape

Last updated: July 31, 2026

The NLM MeSH class "Menstruation-Inducing Agents" is a pharmacologic category rather than a single commercial market. Its principal modern products are mifepristone and misoprostol, used in medication abortion, miscarriage management and selected gynecologic indications. The commercial center of gravity is mifepristone, because its approved use depends on a regulated prescription product and a specific treatment regimen. Misoprostol is widely available as a low-cost generic and has limited remaining composition-of-matter patent protection.

The core patent risk has shifted from basic molecule patents to method-of-use claims, formulation claims, distribution controls, regulatory exclusivity and access restrictions. In the United States, generic entry has already occurred for mifepristone, while misoprostol is an established multisource generic. The main competitive variables are FDA approval status, pharmacy and telehealth distribution, state access rules, manufacturing capacity and litigation over FDA regulation.

What drugs are included in the Menstruation-Inducing Agents class?

The MeSH classification covers agents that induce menstrual bleeding or uterine evacuation. It does not define a single FDA therapeutic category or establish common patent ownership.

Active ingredient	Principal relevant use	U.S. commercial status	Patent position
Mifepristone	Medication abortion with misoprostol; medical management of miscarriage; Cushing syndrome at a different dose	Mifeprex, generic mifepristone; Korlym for Cushing syndrome	Core composition patents expired; regulatory, formulation and method-of-use issues remain
Misoprostol	Uterine evacuation with mifepristone; miscarriage management; cervical preparation and obstetric uses	Cytotec and multiple generics	Core composition protection expired; generic market is mature
Dinoprostone	Cervical ripening and labor induction	Prostaglandin products, including vaginal inserts and gels	Product and formulation patents are largely historical; current barriers are manufacturing and regulatory
Prostaglandin analogues and uterotonics	Selected gynecologic and obstetric uses	Mostly generic or hospital-distributed products	Protection depends on dosage form, delivery system and indication

Mifepristone and misoprostol should be analyzed together for abortion-related market assessments because the FDA-approved regimen uses both products. They should be analyzed separately for patent purposes because they have different owners, approval histories and generic structures.

What products currently drive the market?

Mifepristone

Mifepristone is a progesterone receptor antagonist. The FDA approved Mifeprex in 2000 for termination of intrauterine pregnancy through 7 weeks of gestation, later expanded to 10 weeks. FDA labeling states that the product is used with misoprostol and is supplied as a 200 mg tablet. FDA approved a generic version from GenBioPro in 2019. FDA later approved a supplemental application for medication abortion through 70 days of gestation and removed several dispensing restrictions, including the prior in-person dispensing requirement, subject to the applicable risk-management framework (FDA, 2019, 2021, 2023).

Mifepristone also is marketed as Korlym, a 300 mg product for hyperglycemia secondary to hypercortisolism in adults with endogenous Cushing syndrome. Korlym is commercially distinct from Mifeprex and has a separate patent and exclusivity history.

Misoprostol

Misoprostol is a prostaglandin E1 analogue. Cytotec was originally approved for reduction of nonsteroidal anti-inflammatory drug-induced gastric ulcers. Its use with mifepristone for medication abortion became the central commercial application in reproductive health, although the product label and the clinical use history have developed through different regulatory pathways.

Misoprostol is inexpensive, stable at room temperature and available from multiple manufacturers. It is used alone or with mifepristone in medication abortion and miscarriage care. Because of its mature generic status, the commercial value is concentrated in supply reliability, institutional contracts and distribution rather than patent exclusivity.

What patents protect mifepristone and misoprostol?

Mifepristone patent estate

The principal historic U.S. mifepristone composition patent was U.S. Patent No. 4,386,085, assigned to Roussel-Uclaf and related entities. That patent covered steroid compounds including mifepristone and expired decades ago. Later U.S. patents covered formulations, treatment regimens and related uses, but the principal molecule-level barrier is no longer active.

A frequently cited later patent is U.S. Patent No. 6,306,802, associated with the use of mifepristone in medical abortion. Its term extended into the early 2020s. Patent expiration did not prevent generic approval because the FDA approved GenBioPro's product through the ANDA pathway after the relevant exclusivity and patent hurdles had been addressed.

Mifepristone's current protection profile is therefore fragmented:

Protection category	Current commercial relevance
Composition of matter	No meaningful U.S. blocking protection
Medication-abortion regimen	Historic patents have expired or are no longer the primary barrier
200 mg tablet formulation	Potentially relevant only if an unexpired, listed claim covers the approved product
Cushing syndrome use	Separate Korlym estate with commercial significance
Manufacturing process	May create supplier or process advantages but generally does not block a compliant finished-dose competitor
Distribution controls	Regulatory requirements can affect access without creating patent exclusivity

Misoprostol patent estate

Misoprostol's original composition and product patents are expired. Cytotec is exposed to established generic competition. No broad, commercially meaningful patent monopoly covers the active ingredient for medication-abortion use in the United States.

Potentially relevant rights can still arise around:

• Combination products containing mifepristone and misoprostol.
• Fixed-dose or co-packaged regimens.
• Modified-release or site-specific delivery systems.
• Sublingual, buccal or vaginal formulations.
• Dosing schedules and treatment methods.
• Manufacturing processes and impurity controls.

These rights generally have narrower claim scope than a composition patent. They may support licensing, product differentiation or litigation, but they are less likely to remove generic misoprostol from the market.

When do mifepristone and misoprostol lose exclusivity?

Mifepristone and misoprostol have already lost core U.S. molecule exclusivity. The relevant commercial timeline is:

Year	Event
1980s	U.S. composition patents for mifepristone issue
1985	Misoprostol receives U.S. approval as Cytotec for ulcer prevention
2000	FDA approves Mifeprex for medication abortion
2016	FDA expands the Mifeprex regimen through 70 days of gestation and changes prescribing requirements
2019	FDA approves GenBioPro's generic mifepristone
2020-2023	FDA modifies dispensing requirements and permits certified pharmacies under the applicable program
2024	Supreme Court dismisses the challenge to FDA's mifepristone actions for lack of standing
Present	Market competition is primarily generic, regulatory and distribution-driven

The key distinction is between patent expiration and market accessibility. Expiration permits competition under the Hatch-Waxman framework. It does not guarantee nationwide dispensing because state laws, pharmacy policies, provider certification and litigation can constrain supply.

What is the Orange Book status of mifepristone and misoprostol?

The FDA Orange Book lists approved products, patent information submitted by sponsors and applicable exclusivity data. Orange Book analysis must distinguish among Mifeprex, generic mifepristone, Korlym, Cytotec and generic misoprostol because they have different application numbers and indications.

For medication abortion, the most important regulatory facts are:

• Mifeprex is an NDA product approved under NDA 020687.
• Generic mifepristone is approved through an ANDA and is therapeutically equivalent to the reference product for the approved conditions.
• Cytotec and generic misoprostol are separate products with older labeling histories.
• Korlym is a separate NDA product for Cushing syndrome and should not be treated as interchangeable with Mifeprex.
• Orange Book listings do not capture every possible patent affecting supply, including process patents, foreign patents, unlisted formulation claims or regulatory restrictions.

A Paragraph IV filing is most consequential when an ANDA applicant certifies that a listed patent is invalid, unenforceable or will not be infringed. Because generic mifepristone is already approved, the principal Paragraph IV event for the medication-abortion market has occurred. Future challenges are more likely to target newly listed formulation, combination or use patents than the original active ingredient.

Which companies are challenging or competing with branded mifepristone?

The principal competitive structure is:

Company or organization	Product or role	Competitive significance
Danco Laboratories	Mifeprex	Original U.S. medication-abortion sponsor and commercial supplier
GenBioPro	Generic mifepristone	First FDA-approved U.S. generic mifepristone supplier
Corcept Therapeutics	Korlym	Separate mifepristone product for Cushing syndrome
Misoprostol manufacturers	Generic misoprostol	Supply-side competition in combination and misoprostol-only regimens
Compounding pharmacies	Customized or compounded products where legally permitted	Potential alternative supply channel, subject to federal and state requirements

The market does not have a conventional branded-versus-generic structure in which one branded product controls all demand. Mifeprex retains brand recognition and an established distribution network, but generic mifepristone has materially reduced the value of legacy patent protection.

What patent litigation affects mifepristone?

The most significant recent U.S. litigation has concerned FDA approval and restrictions rather than a conventional patent infringement case.

In Alliance for Hippocratic Medicine v. FDA, plaintiffs challenged the 2000 approval of Mifeprex and subsequent FDA actions. The U.S. Supreme Court held in 2024 that the plaintiffs lacked standing, leaving FDA approval and the challenged regulatory actions in place (U.S. Supreme Court, 2024).

The case had several commercial implications:

1. It created potential nationwide disruption risk even though the dispute was not a patent invalidity action.
2. It highlighted the value of FDA approval and distribution controls as commercial assets.
3. It increased supply-chain and launch risk for both branded and generic suppliers.
4. It did not restore expired composition patents or create new market exclusivity.

Separate state-level disputes continue to affect access. Those disputes can change the addressable market without changing the patent term.

How strong is the patent estate for menstruation-inducing agents?

Mifepristone

Mifepristone has a weak legacy composition estate and a moderate regulatory-commercial position. Its strongest assets are FDA approval, established clinical use, manufacturing know-how, provider familiarity and distribution infrastructure. New entrants face regulatory and operational hurdles but not a broad active molecule patent.

Misoprostol

Misoprostol has a weak patent estate and high generic substitutability. The product is inexpensive, widely manufactured and used for multiple indications. Commercial defensibility depends on quality, supply reliability, institutional relationships and regulatory compliance.

New formulations

A new combination, delivery system or dosage form could create stronger protection if it produces a clinically meaningful advantage. The most defensible claims would likely relate to:

• Improved stability or shelf life.
• Reduced dosing burden.
• A fixed-dose combination.
• A controlled-release or site-specific formulation.
• A validated treatment protocol with a distinct clinical outcome.

Method-of-use claims face a narrower competitive moat because physicians and pharmacies may avoid infringement through alternative regimens, and generic labels can create complex induced-infringement questions.

What formulation patents protect abortion and miscarriage regimens?

Formulation patents are more relevant to future products than to existing generic mifepristone and misoprostol. Potential products include fixed-dose combination packs, orally disintegrating tablets, vaginal formulations and simplified treatment kits.

A formulation patent must be assessed against:

• The exact active ingredients and strengths.
• The release profile.
• Excipients and manufacturing parameters.
• The claimed treatment population.
• FDA-approved labeling.
• Whether the patent is listed in the Orange Book.
• Whether the claim covers the commercial product or only a laboratory formulation.

A co-packaged product may improve adherence and logistics, but packaging alone generally provides a narrower patent position than a new chemical entity. Sponsors must also consider whether the product's regulatory route supports Orange Book listing and a meaningful Hatch-Waxman enforcement strategy.

What generic launch risks exist?

Generic entry is legally possible but operationally uneven. The main risks are:

Risk	Effect on launch
State abortion restrictions	Limits the addressable market and pharmacy participation
FDA certification requirements	Adds operational controls and documentation
Litigation over FDA authority	Can disrupt supply despite patent expiration
Pharmacy and wholesaler policies	May restrict distribution beyond formal FDA requirements
API and finished-dose supply	Creates shortage or allocation risk
Product-specific labeling	Can affect substitution and prescribing
Foreign regulatory restrictions	Complicate cross-border sourcing and manufacturing

For misoprostol, generic launch risk is low from a patent perspective. For mifepristone, patent risk is also low at the molecule level, but regulatory and distribution risk is materially higher.

How does the patent landscape compare with competing reproductive-health drugs?

Product class	Patent strength	Generic competition	Principal market barrier
Mifepristone for medication abortion	Low to moderate	Established	FDA controls, state law and distribution
Misoprostol	Low	Extensive	Supply and institutional purchasing
Long-acting contraceptive implants	Moderate to high for device and formulation claims	Product-specific	Device patents and manufacturing
Hormonal intrauterine systems	Moderate to high	Increasing	Device, formulation and regulatory complexity
Dinoprostone delivery systems	Low to moderate	Variable by dosage form	Hospital procurement and formulation
Mifepristone for Cushing syndrome	Moderate	Limited relative to abortion indication	Indication-specific patents and market exclusivity

The closest commercial comparison is between mifepristone and misoprostol. Mifepristone carries greater regulatory and political exposure but has higher strategic value in the approved combination regimen. Misoprostol has greater generic penetration and lower unit economics.

What licensing deals and manufacturing barriers matter?

The original development and U.S. commercialization of mifepristone involved Roussel-Uclaf and later Danco Laboratories. The U.S. commercial model was shaped by licensing and distribution arrangements rather than a single vertically integrated originator structure. Danco has remained the principal Mifeprex sponsor in the United States.

Manufacturing barriers include:

• Qualified API suppliers.
• Compliance with current good manufacturing practice.
• Batch testing and impurity controls.
• Secure packaging and controlled distribution.
• Ability to maintain supply during litigation or policy changes.
• Regulatory documentation for generic substitution.

These barriers can support a supplier's negotiating position even when patent protection is weak. They do not, however, provide the same legal exclusivity as an active patent.

What is the revenue exposure to patent expiry?

Mifepristone revenue exposure is concentrated in two different markets:

1. Medication abortion, where competition is primarily between Mifeprex, generic mifepristone and misoprostol suppliers.
2. Cushing syndrome, where Korlym has historically had a more valuable specialty-pharmaceutical profile and a more significant product-specific patent strategy.

For medication abortion, legacy patent expiry has already shifted value away from exclusivity and toward volume, access and supply reliability. For Korlym, patent settlements, indication-specific claims and orphan-drug economics have greater relevance. Misoprostol has limited patent-linked revenue exposure because its active ingredient has long been generic.

Key Takeaways

• The MeSH class is a pharmacologic category, not a unified patent market.
• Mifepristone and misoprostol are the principal commercial products for medication abortion.
• Core U.S. composition patents for both active ingredients have expired.
• Generic mifepristone was FDA-approved in 2019; misoprostol has long had multisource generic competition.
• Current risks center on FDA regulation, state access laws, pharmacy distribution, manufacturing and supply continuity.
• Formulation, combination-product and method-of-use patents are the main potential sources of future exclusivity.
• Mifepristone for Cushing syndrome has a separate commercial and patent profile from Mifeprex.
• The 2024 Supreme Court decision preserved FDA's mifepristone approval and regulatory actions but did not create patent exclusivity.
• Patent strength is weak for misoprostol, weak at the molecule level for mifepristone and potentially stronger for new delivery systems or combination products.

FAQs

Is mifepristone still patent protected in the United States?

Mifepristone's core composition patents have expired. Any remaining relevant protection depends on specific formulation, method-of-use, combination-product or product-specific claims.

Can a generic company sell misoprostol for medication abortion?

Generic misoprostol is FDA-approved for its labeled indications and is widely used in reproductive-health care. Its use in a particular regimen depends on prescribing, labeling and applicable federal and state law.

Does the Mifeprex REMS create market exclusivity?

No. A REMS can impose dispensing and certification requirements, but it is not a patent and does not by itself prevent FDA approval of a therapeutically equivalent generic.

Are mifepristone and misoprostol interchangeable?

No. They are different active ingredients with different pharmacology and regulatory histories. They are often used together in an FDA-approved medication-abortion regimen, but one is not a direct substitute for the other.

Could a new mifepristone-misoprostol combination obtain patent protection?

Yes. A sponsor could seek patents covering a specific fixed-dose combination, delivery system, formulation, manufacturing process or treatment method. The commercial value would depend on claim scope, FDA approval and whether the claims are listed and enforceable against generic applicants.

References

1. Alliance for Hippocratic Medicine v. Food and Drug Administration, 602 U.S. 367 (2024).

2. Corcept Therapeutics, Inc. (2024). Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. U.S. Securities and Exchange Commission.

3. Danco Laboratories, LLC. (2024). Mifeprex prescribing information. U.S. Food and Drug Administration.

4. U.S. Food and Drug Administration. (2019). FDA approves first generic version of Mifeprex. https://www.fda.gov

5. U.S. Food and Drug Administration. (2021). FDA announces changes to Mifeprex dispensing requirements. https://www.fda.gov

6. U.S. Food and Drug Administration. (2023). Mifepristone REMS modification. https://www.fda.gov

7. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations. Orange Book. https://www.accessdata.fda.gov/scripts/cder/ob/

8. U.S. Patent No. 4,386,085. (1983). 19-nor steroids. United States Patent and Trademark Office.

9. U.S. Patent No. 6,306,802. (2001). Method for inducing labor or terminating pregnancy. United States Patent and Trademark Office.