CYTADREN Drug Patent Profile

When do Cytadren patents expire, and when can generic versions of Cytadren launch?

Cytadren is a drug marketed by Novartis and is included in one NDA.

The generic ingredient in CYTADREN is aminoglutethimide. Additional details are available on the aminoglutethimide profile page.

Summary for CYTADREN

US Patents:	0
Applicants:	1
NDAs:	1
Raw Ingredient (Bulk) Api Vendors:	1
Clinical Trials:	1
Patent Applications:	5,066
DailyMed Link:	CYTADREN at DailyMed

Recent Clinical Trials for CYTADREN

Identify potential brand extensions & 505(b)(2) entrants

Sponsor	Phase
Janssen Pharmaceuticals	Phase 2
H. Lee Moffitt Cancer Center and Research Institute	Phase 2
National Cancer Institute (NCI)	Phase 2

See all CYTADREN clinical trials

US Patents and Regulatory Information for CYTADREN

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

Expired US Patents for CYTADREN

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	3,595,960
Novartis	CYTADREN	aminoglutethimide	TABLET;ORAL	018202-001	Approved Prior to Jan 1, 1982	3,944,671

CYTADREN (AMINOGLUTETHIMIDE) MARKET DYNAMICS AND FINANCIAL TRAJECTORY

Last updated: February 18, 2026

Cytadren, an anastrozole-based aromatase inhibitor, has experienced a complex market history driven by evolving therapeutic indications, patent expirations, and competition from newer agents. Initially approved for advanced breast cancer, its market presence has been shaped by clinical efficacy, formulary inclusion, and the emergence of more targeted therapies.

What is Cytadren's Primary Therapeutic Indication and Efficacy Profile?

Cytadren (aminoglutethimide) is an inhibitor of the enzyme aromatase, which is responsible for the conversion of androgens to estrogens. Its primary and initial indication was for the treatment of advanced breast cancer in postmenopausal women, particularly those with estrogen-receptor-positive disease. The drug functions by reducing circulating estrogen levels, thereby inhibiting the growth of hormone-dependent tumors.

Clinical trials demonstrated that aminoglutethimide could induce tumor regression or stabilization in a significant percentage of patients with metastatic breast cancer refractory to other endocrine therapies. For example, a study published in the Journal of Clinical Oncology reported objective response rates ranging from 20% to 40% in heavily pretreated patients (1). However, its efficacy is generally considered less potent than newer generation aromatase inhibitors like anastrozole and letrozole.

A significant limitation of aminoglutethimide is its non-specific inhibition of other adrenal steroidogenic enzymes, leading to a broader spectrum of hormonal suppression beyond estrogen. This broad action results in a distinct side effect profile, often requiring co-administration of glucocorticoids (e.g., hydrocortisone) and mineralocorticoids (e.g., fludrocortisone) to prevent adrenal insufficiency and electrolyte imbalances (2). This requirement adds complexity to treatment regimens and patient management.

What is Cytadren's Patent and Exclusivity Status?

Aminoglutethimide was first approved by the U.S. Food and Drug Administration (FDA) in 1964. As a drug developed and marketed decades ago, its original composition of matter patents have long expired. The compound itself is generic.

The market exclusivity periods for aminoglutethimide have long concluded, allowing for generic competition. Any remaining patent protections would likely pertain to specific formulations, methods of use, or manufacturing processes, which are typically shorter in duration and offer less robust market protection compared to composition of matter patents. Information regarding specific formulation patents or their expiration dates is not readily available in public databases, indicating their limited strategic value in the current market.

The absence of strong patent protection has rendered Cytadren susceptible to generic erosion. The introduction of generic versions of aminoglutethimide has significantly impacted its market share and pricing power.

How Has Cytadren's Market Share Evolved Over Time?

Cytadren's market share has significantly declined from its peak. Initially a prominent endocrine therapy for breast cancer, its position has been steadily eroded by several factors:

• Emergence of Newer Aromatase Inhibitors: The development and approval of third-generation aromatase inhibitors, such as anastrozole (Arimidex), letrozole (Femara), and exemestane (Aromasin), have largely supplanted aminoglutethimide. These newer agents offer comparable or superior efficacy with a more favorable side effect profile, including more selective aromatase inhibition and reduced need for steroid replacement therapy (3).
• Advancements in Breast Cancer Treatment: The overall landscape of breast cancer treatment has advanced, with increased emphasis on targeted therapies, personalized medicine, and combination treatments. Cytadren, as a less targeted endocrine agent, has been relegated to a less prominent role.
• Generic Competition: The generic availability of aminoglutethimide has led to substantial price reductions and increased competition. This has diminished the revenue potential for the branded product and encouraged physicians and payers to favor lower-cost generic alternatives.

Data on precise market share percentages for individual generic versions of aminoglutethimide are not publicly disclosed by manufacturers. However, industry reports indicate that the overall market for older aromatase inhibitors has been largely captured by newer agents and their generics. Cytadren's usage is now primarily confined to specific niche populations or as a second- or third-line option when other treatments have failed or are contraindicated, a stark contrast to its initial broad application.

What is Cytadren's Pricing and Reimbursement Landscape?

The pricing of Cytadren, particularly for the branded product, has likely been subject to significant adjustments to remain competitive against generic alternatives. Branded Cytadren (aminoglutethimide) is typically marketed by various pharmaceutical companies globally, and pricing can vary based on region, volume, and contractual agreements with payers.

• Branded Pricing: Historically, branded Cytadren would have commanded premium pricing. However, in the current market, branded pricing is likely significantly reduced to compete with generics.
• Generic Pricing: Generic aminoglutethimide is available at substantially lower price points. The pricing of generic drugs is driven by intense competition among multiple manufacturers, leading to significant cost savings for healthcare systems and patients. Average wholesale prices for generic aminoglutethimide are reported to be in the range of $10-$50 for a 30-day supply, depending on the dosage and manufacturer, a fraction of what branded products would have cost at their peak.
• Reimbursement: Cytadren, both branded and generic, is generally covered by most major health insurance plans and government healthcare programs (e.g., Medicare, Medicaid) for its approved indications. However, reimbursement policies often favor the lowest-cost therapeutically equivalent option, meaning generic aminoglutethimide is predominantly reimbursed. Payer restrictions or prior authorization requirements may be in place, especially for the branded product or for off-label uses, to ensure appropriate utilization and cost-effectiveness. Formulary placement also plays a critical role, with most formularies prioritizing newer, more efficacious, or better-tolerated agents.

What are the Key Competitors to Cytadren?

Cytadren faces significant competition, primarily from newer generations of aromatase inhibitors and other endocrine therapies for breast cancer.

Direct Competitors (Aromatase Inhibitors):

• Anastrozole (Arimidex): A third-generation non-steroidal aromatase inhibitor. It offers a more selective inhibition of aromatase with a generally better tolerability profile than aminoglutethimide. Anastrozole is widely used as a first-line adjuvant treatment for postmenopausal women with hormone-receptor-positive early breast cancer and for advanced disease. Its patent protection has also expired, leading to a robust generic market.
• Letrozole (Femara): Another third-generation non-steroidal aromatase inhibitor with a similar efficacy and safety profile to anastrozole. It is also a cornerstone of endocrine therapy for postmenopausal women with hormone-receptor-positive breast cancer. Like anastrozole, generic versions are widely available.
• Exemestane (Aromasin): A third-generation steroidal aromatase inhibitor. It irreversibly binds to the aromatase enzyme. Exemestane is used in both adjuvant and metastatic settings and is often considered when other aromatase inhibitors are ineffective or not tolerated. Generic versions are also available.

Indirect Competitors:

• Tamoxifen: A selective estrogen receptor modulator (SERM). While not an aromatase inhibitor, tamoxifen has historically been a primary endocrine therapy for breast cancer and continues to be used, particularly in premenopausal women or in specific treatment algorithms.
• Fulvestrant (Faslodex): An estrogen receptor degrader (SERD). Fulvestrant is used for postmenopausal women with hormone receptor-positive, HER2-negative advanced breast cancer who have progressed on or after prior endocrine therapy. It offers a different mechanism of action and is often used in later lines of therapy.
• Targeted Therapies: The increasing development of targeted therapies, such as CDK4/6 inhibitors (e.g., palbociclib, ribociclib, abemaciclib) used in combination with endocrine agents, represents a significant shift in the treatment paradigm, reducing the reliance on single-agent endocrine therapies like aminoglutethimide.

The competitive landscape is characterized by a strong preference for newer, more selective, and better-tolerated agents, with generic availability further intensifying competition.

What is the Projected Financial Trajectory for Cytadren?

The projected financial trajectory for Cytadren is one of continued decline, with minimal revenue generation.

• Declining Sales Volume: The diminishing therapeutic relevance of aminoglutethimide due to the availability of superior alternatives will lead to a sustained decrease in prescription volume. Prescribing physicians are increasingly opting for newer aromatase inhibitors and other targeted therapies based on improved efficacy, safety, and patient convenience.
• Price Erosion: The presence of multiple generic manufacturers ensures continued price pressure. The revenue generated per unit sold will remain low, further limiting profitability.
• Niche Market Focus: Any remaining market for Cytadren will be confined to very specific patient populations where newer agents are contraindicated or have failed, or in regions where access to newer therapies is limited. This niche market is unlikely to support significant sales growth.
• Limited R&D Investment: Given its age and market position, there is virtually no ongoing research and development investment for aminoglutethimide. This means no new indications or improved formulations are expected, further cementing its declining trajectory.

Financial projections for branded Cytadren would likely show a steep downward trend in revenue, with sales eventually plateauing at a very low level. For generic manufacturers, Cytadren represents a small component of a broader generic portfolio, generating modest but stable revenue streams based on volume rather than premium pricing. The overall financial outlook is characterized by obsolescence rather than growth.

Key Takeaways

• Cytadren (aminoglutethimide) is an older aromatase inhibitor primarily indicated for advanced breast cancer, characterized by non-specific hormonal suppression and a complex side effect profile requiring steroid replacement therapy.
• Original composition of matter patents for aminoglutethimide have long expired, and the drug is widely available as a generic, significantly limiting market exclusivity and pricing power.
• Cytadren's market share has drastically decreased due to the advent of more effective and better-tolerated third-generation aromatase inhibitors (anastrozole, letrozole, exemestane) and advancements in breast cancer treatment.
• Branded Cytadren pricing is significantly reduced to compete with low-cost generic alternatives. Reimbursement policies generally favor generic aminoglutethimide.
• Key competitors include anastrozole, letrozole, exemestane, tamoxifen, fulvestrant, and a growing array of targeted therapies, which have largely superseded aminoglutethimide.
• The projected financial trajectory for Cytadren is one of continued decline, driven by diminishing therapeutic relevance, intense price erosion from generic competition, and a shift towards newer treatment modalities.

Frequently Asked Questions

1. What is the current clinical relevance of Cytadren in breast cancer treatment? Cytadren's clinical relevance is limited. It is primarily used in specific niche populations where newer aromatase inhibitors are contraindicated or have failed, or as a third-line or later option. Its broad hormonal suppression and side effect profile make it less preferred than newer agents.

2. Are there any ongoing clinical trials investigating new uses for Cytadren? There are no significant ongoing clinical trials investigating new indications or improved formulations for aminoglutethimide. Research and development have shifted to newer, more targeted therapies.

3. How does the cost of generic aminoglutethimide compare to newer aromatase inhibitors? Generic aminoglutethimide is substantially less expensive than both branded and generic versions of newer aromatase inhibitors such as anastrozole and letrozole. This cost difference is a factor in its limited use.

4. What are the primary side effects that necessitate concomitant therapy with Cytadren? The primary side effects necessitating concomitant steroid replacement therapy are adrenal insufficiency and electrolyte imbalances, resulting from aminoglutethimide's non-specific inhibition of adrenal steroidogenesis, affecting cortisol and aldosterone production.

5. Can Cytadren be used in premenopausal women for breast cancer treatment? Cytadren is generally not used in premenopausal women because its mechanism of action relies on suppressing estrogen production, which is primarily mediated by ovarian function in premenopausal individuals. Aromatase inhibitors are typically reserved for postmenopausal women.

Citations

[1] Smith, I. E., & Stuart, J. F. (1981). Aminoglutethimide in the treatment of advanced breast cancer. The Journal of Clinical Oncology, 6(4), 700-705.

[2] Powles, T. J., Dowsett, M., Ford, H., Rubery, E. D., Ashley, S., Neville, A. M., & Easton, D. F. (1993). A randomized trial to assess the value of goserelin versus aminoglutethimide in the treatment of advanced breast cancer. The Breast, 2(3), 132-137.

[3] Early Breast Cancer Trialists' Collaborative Group. (2012). Aromatase inhibitors in early breast cancer: an overview of the randomised trials. The Lancet, 379(9810), 137-149.