Last updated: September 2, 2026

Aminoglutethimide is a mature, largely discontinued endocrine drug with minimal current commercial value. Its historical market depended on two uses: suppression of adrenal steroid production in Cushing syndrome and endocrine treatment of advanced breast cancer. The drug lost commercial relevance as safer and more selective agents entered both markets. No meaningful active U.S. patent or exclusivity barrier supports a branded relaunch, and public financial filings do not report product-level revenue for aminoglutethimide.

What is aminoglutethimide and how does it work?

Aminoglutethimide is an oral steroidogenesis inhibitor formerly marketed in the United States as Cytadren. It inhibits cholesterol conversion to pregnenolone and suppresses several adrenal steroid pathways. It also inhibits aromatase, reducing conversion of androgens to estrogens.

The drug was used in:

Cushing syndrome caused by excess cortisol production.
Advanced or metastatic breast cancer in postmenopausal women.
Less commonly, other hormone-dependent malignancies under specialist supervision.

Its pharmacology created both its therapeutic value and its commercial limitations. Aminoglutethimide is a relatively nonselective endocrine inhibitor and induces hepatic drug-metabolizing enzymes. Patients may develop adrenal insufficiency, rash, nausea, dizziness, lethargy, hypothyroidism, and clinically significant drug interactions. The FDA label required corticosteroid replacement and careful endocrine monitoring in Cushing syndrome treatment [1].

When did aminoglutethimide lose exclusivity?

Aminoglutethimide lost meaningful U.S. market exclusivity decades ago. The drug was approved in the United States long before the modern Hatch-Waxman exclusivity framework became commercially important. No current FDA new chemical entity exclusivity, orphan-drug exclusivity, or pediatric exclusivity protects the product.

Exclusivity category	Aminoglutethimide status
U.S. new chemical entity exclusivity	Expired
U.S. orphan-drug exclusivity	None identified
Pediatric exclusivity	None identified
Active branded patent protection	No commercially relevant protection identified
Generic entry barrier	Primarily manufacturing and demand economics
Current U.S. commercial position	Discontinued or unavailable through ordinary retail channels

The economic life of aminoglutethimide ended through therapeutic substitution and declining demand rather than through a single patent event. In breast cancer, tamoxifen and later-generation aromatase inhibitors displaced aminoglutethimide. In Cushing syndrome, ketoconazole, metyrapone, mitotane, pasireotide, osilodrostat, and surgery became more important alternatives [2,3].

What patents protect aminoglutethimide?

No commercially significant active U.S. patent estate is associated with the aminoglutethimide active ingredient, the historical Cytadren product, or its conventional 250-mg tablet formulation.

Active ingredient and composition patents

Aminoglutethimide was discovered and commercialized many decades ago. Any original compound or composition patents would have expired under ordinary U.S. patent terms. The compound is therefore available for generic manufacture from a patent perspective.

Formulation patents

The historical product was an immediate-release oral tablet. There is no widely recognized active U.S. formulation patent covering Cytadren or a proprietary extended-release delivery system. The absence of a differentiated formulation limits the opportunity to create a protected follow-on product.

Method-of-use patents

Historical treatment methods for Cushing syndrome and advanced breast cancer are generally too old to support current exclusivity. No important live U.S. method-of-use patent is broadly associated with aminoglutethimide.

Manufacturing and process barriers

The principal barriers are operational rather than legal:

Low and irregular demand.
Limited supplier interest in active pharmaceutical ingredient production.
Need for quality controls around a potent endocrine-active compound.
Regulatory costs that may exceed attainable sales.
Limited clinical demand outside specialist endocrine practice.
Competition from better-supported products.

These factors can restrict supply even when no patent blocks entry. A technically open market can still function as a de facto single-source or no-source market if manufacturers cannot earn an acceptable return.

What is the FDA regulatory status of aminoglutethimide?

The FDA-approved U.S. product was Cytadren tablets, historically supplied as 250 mg aminoglutethimide. Its labeled indications included advanced breast cancer and Cushing syndrome [1].

The product is no longer a mainstream U.S. commercial therapy. FDA availability data and commercial drug databases have treated Cytadren as discontinued or unavailable in the United States. Discontinuation does not necessarily mean the FDA withdrew the drug for safety reasons. In mature products, the manufacturer may discontinue production for commercial reasons while the underlying approval remains a historical regulatory record.

FDA-related issue	Status
Active branded U.S. marketing position	No meaningful current position
FDA-approved historical indication	Advanced breast cancer; Cushing syndrome
Current regulatory value	Limited
Orange Book relevance	No meaningful active exclusivity listing
ANDA opportunity	Legally possible, commercially weak
Shortage or supply risk	High if specialist demand depends on limited suppliers

The FDA label is clinically important because it documents the drug’s adverse-effect profile and monitoring requirements. It also explains why aminoglutethimide has not retained a broad market despite its steroidogenesis-inhibiting activity.

How did aminoglutethimide’s oncology market decline?

Aminoglutethimide’s breast cancer market contracted as oncology treatment moved toward more selective and tolerable endocrine therapies.

Historically, aminoglutethimide was used in postmenopausal women with advanced disease because estrogen deprivation could slow hormone-sensitive tumors. Its aromatase inhibition was clinically relevant, but the drug was less selective than modern aromatase inhibitors.

The competitive sequence was unfavorable:

Tamoxifen established a more usable endocrine treatment option.
Anastrozole, letrozole, and exemestane provided more selective aromatase inhibition.
Improved chemotherapy, targeted therapy, and biomarker-based treatment reduced reliance on older endocrine agents.
Generic competition compressed the price of older drugs without restoring volume.
Aminoglutethimide became a historical or niche option rather than a standard breast cancer product.

The drug’s oncology economics were therefore damaged by both clinical substitution and pricing pressure. Even a low-cost generic could not compete effectively where physicians preferred better-characterized and better-tolerated alternatives.

How did the Cushing syndrome market change?

Cushing syndrome preserved the strongest clinical rationale for aminoglutethimide, but it did not preserve a large commercial market.

The drug can reduce cortisol production, but treatment requires specialist management. Corticosteroid replacement may be needed because adrenal suppression can become excessive. Enzyme induction creates interaction risks, and the adverse-effect burden limits routine use.

The modern Cushing syndrome market includes:

Ketoconazole, which inhibits steroidogenesis but carries hepatotoxicity concerns.
Metyrapone, which directly inhibits cortisol synthesis.
Mitotane, particularly in adrenal-origin disease.
Pasireotide, a pituitary-directed therapy.
Osilodrostat, a newer steroidogenesis inhibitor.
Surgery and radiation, depending on the underlying cause.

Osilodrostat is especially important competitively because it was developed specifically for hypercortisolism and supported by contemporary clinical development and regulatory investment. Aminoglutethimide lacks comparable commercial infrastructure.

What is the financial trajectory of aminoglutethimide?

Aminoglutethimide followed a typical late-life generic-drug trajectory:

Period	Commercial condition	Financial effect
Initial commercialization	Branded endocrine and oncology product	Specialty revenue opportunity
Generic era	Multiple low-price alternatives and limited differentiation	Margin compression
Late branded life	Narrow specialist use and declining prescribing	Falling sales
Post-discontinuation period	Limited or irregular supply	Minimal recognized product revenue
Current position	No material branded franchise	No visible growth platform

Public company filings do not provide a reliable, standalone revenue series for aminoglutethimide. Historical manufacturers generally reported it within broader pharmaceutical portfolios, while later generic suppliers did not identify the product as a material revenue category.

The financial trajectory can still be assessed through market structure:

Volume declined as standard-of-care therapies changed.
Price declined after generic entry.
Manufacturing scale deteriorated because demand became too small.
Regulatory maintenance costs became harder to justify.
No protected formulation or new indication created a second product life.
Commercial value shifted from brand equity to occasional supply availability.

Aminoglutethimide is therefore an example of a drug with residual clinical utility but negligible franchise value. Any revenue today would be expected to come from small-volume specialty supply rather than a conventional branded pharmaceutical business.

Which companies are challenging or replacing aminoglutethimide?

There is no major current Paragraph IV campaign focused on aminoglutethimide. Its patent position is too old and commercially unimportant to support a high-value litigation contest.

The more relevant competitive challenge comes from replacement products:

Competitor	Primary market	Competitive advantage
Metyrapone	Cushing syndrome	Direct cortisol-synthesis inhibition and specialist use
Ketoconazole	Cushing syndrome	Established steroidogenesis inhibition
Osilodrostat	Cushing syndrome	Modern, indication-specific development and approval
Mitotane	Adrenocortical disease	Established role in adrenal malignancy
Anastrozole	Breast cancer	Selective aromatase inhibition
Letrozole	Breast cancer	Selective aromatase inhibition
Exemestane	Breast cancer	Steroidal aromatase inhibition
Tamoxifen	Breast cancer	Established endocrine therapy and broad historical use

For breast cancer, the principal displacement came from the aromatase inhibitor class. For Cushing syndrome, the principal displacement came from newer steroidogenesis inhibitors and more targeted therapies.

What Paragraph IV and generic launch risks exist?

A Paragraph IV challenge has little practical relevance because no economically important listed branded product appears to maintain a current exclusivity position.

A hypothetical generic launch would face low legal risk but high commercial risk:

The reference product has limited or no active commercial pull.
Prescribers have migrated to alternatives.
Reimbursement economics may be weak.
Minimum manufacturing volumes may be difficult to sustain.
Distribution through specialty pharmacies may be fragmented.
The product may require physician education to reestablish use.
Hospitals and endocrinologists may prefer currently supported products.

The most plausible launch model would be a limited-distribution generic serving patients who cannot tolerate or access competing steroidogenesis inhibitors. That would create a niche supply business, not a large generic franchise.

How strong is the aminoglutethimide patent estate?

The patent estate is weak from a current commercial perspective.

Patent-strength factor	Assessment
Compound protection	Expired
Core composition protection	Expired
Formulation protection	No material active protection identified
Method-of-use protection	No material active protection identified
Patent litigation leverage	Very low
Regulatory exclusivity	None of commercial significance
Freedom to operate	Broad, subject to ordinary regulatory requirements
Commercial defensibility	Low

A new sponsor could potentially pursue a reformulated product or a new indication, but that strategy would require fresh clinical, regulatory, and commercial investment. The historical safety profile and crowded endocrine-treatment landscape would make a relaunch difficult to justify without a clearly differentiated formulation or patient population.

What licensing deals affect aminoglutethimide?

No major current licensing transaction is associated with aminoglutethimide. Its historical commercialization involved conventional manufacturer and distributor arrangements rather than a visible modern licensing platform.

The absence of licensing activity reflects the product’s economics. A licensee would obtain little strategic value from an unprotected molecule with declining demand unless it had a specific supply, geographic, or specialty-care rationale.

Geographic availability may vary. Older endocrine drugs can remain accessible in selected countries through local manufacturers or hospital channels even after disappearing from the U.S. market. That availability does not imply a durable global franchise. It usually reflects local prescribing practices, registration status, and supplier economics.

Key Takeaways

Aminoglutethimide is a historical endocrine drug with residual specialist utility.
Its U.S. branded market was built around Cytadren and has largely ended.
Core compound, formulation, and method-of-use protections are expired or commercially irrelevant.
No material FDA exclusivity or active Orange Book barrier supports a major generic litigation strategy.
Breast cancer use declined because selective aromatase inhibitors and other endocrine therapies replaced it.
Cushing syndrome remains the more relevant clinical setting, but newer agents have stronger regulatory and commercial support.
Product-level revenue data are not publicly reported, but the market trajectory is clearly one of volume decline, price compression, and eventual discontinuation.
Future commercial opportunity is limited to specialty supply, selected geographies, or a differentiated reformulation.
Manufacturing availability, not patent protection, is the main barrier to market participation.

Frequently Asked Questions

Is aminoglutethimide still available in the United States?

Aminoglutethimide is not a routine U.S. retail product. Historical Cytadren marketing ended, and access may depend on limited specialty or compounded supply.

Was aminoglutethimide withdrawn for safety reasons?

Commercial discontinuation does not establish a safety withdrawal. The drug has important adverse effects and monitoring requirements, but its market decline primarily reflected obsolescence and competition.

Can a generic company still launch aminoglutethimide?

A generic launch is legally possible in principle because the core intellectual property is old. The principal obstacle is limited and uncertain demand rather than patent infringement risk.

Is aminoglutethimide used for adrenal cancer?

It has historical relevance in steroid-producing endocrine disease, but mitotane and other disease-specific treatments are more established in adrenocortical carcinoma.

Could aminoglutethimide be repurposed for a new indication?

A repurposing strategy could create new protection only through a qualifying formulation, method, or clinical-development pathway. The commercial case would depend on demonstrating an advantage over modern steroidogenesis inhibitors.

References

U.S. Food and Drug Administration. (2000). Cytadren (aminoglutethimide) tablets: Prescribing information. FDA archival labeling.
National Cancer Institute. (n.d.). Breast cancer treatment: Health professional version. National Institutes of Health.
Fleseriu, M., Biller, B. M. K., Findling, J. W., Molitch, M. E., Schteingart, D. E., Gross, C., & Society Working Group. (2016). Consensus on diagnosis and management of Cushing’s disease: A guideline update. The Lancet Diabetes & Endocrinology, 4(10), 847-861.
U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs database. https://www.accessdata.fda.gov/scripts/cder/daf/
U.S. Food and Drug Administration. (n.d.). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/ <|endoftext|>

US Patents:	0
Tradenames:	1
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	111
Clinical Trials:	6
DailyMed Link:	aminoglutethimide at DailyMed

Sponsor	Phase
Columbia University	Phase 2
Federal University of São Paulo	Phase 4
Fundação de Amparo à Pesquisa do Estado de São Paulo	Phase 4

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Novartis	CYTADREN	aminoglutethimide	TABLET;ORAL	018202-001	Approved Prior to Jan 1, 1982		DISCN	No	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

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	Patent No.	Patent Expiration
Novartis	CYTADREN	aminoglutethimide	TABLET;ORAL	018202-001	Approved Prior to Jan 1, 1982	⤷ Start Trial	⤷ Start Trial
Novartis	CYTADREN	aminoglutethimide	TABLET;ORAL	018202-001	Approved Prior to Jan 1, 1982	⤷ Start Trial	⤷ Start Trial
>Applicant	>Tradename	>Generic Name	>Dosage	>NDA	>Approval Date	>Patent No.	>Patent Expiration

Aminoglutethimide - Generic Drug Details

What are the generic drug sources for aminoglutethimide and what is the scope of freedom to operate?

Summary for aminoglutethimide

Recent Clinical Trials for aminoglutethimide

Medical Subject Heading (MeSH) Categories for aminoglutethimide

Anatomical Therapeutic Chemical (ATC) Classes for aminoglutethimide

US Patents and Regulatory Information for aminoglutethimide

Expired US Patents for aminoglutethimide

Aminoglutethimide Market Dynamics, Patent Position, and Financial Trajectory