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Estramustine phosphate sodium - Generic Drug Details
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What are the generic drug sources for estramustine phosphate sodium and what is the scope of patent protection?
Estramustine phosphate sodium
is the generic ingredient in one branded drug marketed by Pharmacia And Upjohn and is included in one NDA. Additional information is available in the individual branded drug profile pages.Summary for estramustine phosphate sodium
| US Patents: | 0 |
| Tradenames: | 1 |
| Applicants: | 1 |
| NDAs: | 1 |
| Drug Master File Entries: | 1 |
| Raw Ingredient (Bulk) Api Vendors: | 55 |
| Clinical Trials: | 31 |
| What excipients (inactive ingredients) are in estramustine phosphate sodium? | estramustine phosphate sodium excipients list |
| DailyMed Link: | estramustine phosphate sodium at DailyMed |
Recent Clinical Trials for estramustine phosphate sodium
Identify potential brand extensions & 505(b)(2) entrants
| Sponsor | Phase |
|---|---|
| University of Massachusetts, Worcester | Phase 2 |
| National Institutes of Health Clinical Center (CC) | Phase 2 |
| Dana-Farber Cancer Institute | Phase 2 |
Medical Subject Heading (MeSH) Categories for estramustine phosphate sodium
Anatomical Therapeutic Chemical (ATC) Classes for estramustine phosphate sodium
US Patents and Regulatory Information for estramustine phosphate sodium
| Applicant | Tradename | Generic Name | Dosage | NDA | Approval Date | TE | Type | RLD | RS | Patent No. | Patent Expiration | Product | Substance | Delist Req. | Exclusivity Expiration |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pharmacia And Upjohn | EMCYT | estramustine phosphate sodium | CAPSULE;ORAL | 018045-001 | Approved Prior to Jan 1, 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 |
Estramustine Phosphate Sodium Market Dynamics, Patent Status, and Financial Trajectory
Estramustine phosphate sodium is a legacy oral antineoplastic used for metastatic or progressive prostate cancer. Its commercial market is now limited by obsolete clinical positioning, competition from androgen-receptor pathway inhibitors and taxane chemotherapy, and the absence of meaningful regulatory exclusivity. Public filings do not provide a standalone revenue series for estramustine phosphate sodium, but the product’s commercial trajectory is clear: a once-differentiated hormonal chemotherapy product has become a low-volume, maintenance-market medicine with limited growth potential.
What is estramustine phosphate sodium used for?
Estramustine phosphate sodium is an oral phosphate ester prodrug that combines an estrogenic moiety with a nitrogen mustard component. The product historically marketed in the United States as Emcyt was approved for the palliative treatment of metastatic and progressive prostate carcinoma.
| Attribute | Estramustine phosphate sodium |
|---|---|
| Brand | Emcyt |
| Active ingredient | Estramustine phosphate sodium |
| Dosage form | Oral capsules |
| U.S. strength | 140 mg |
| Original U.S. sponsor | Pharmacia; later associated with Pfizer |
| U.S. regulatory application | NDA 018919 |
| Primary indication | Metastatic or progressive prostate cancer |
| Drug class | Estrogenic antineoplastic and alkylating agent |
| Current market position | Legacy, niche oncology product |
| Biosimilar exposure | None; this is a small molecule |
| Main commercial substitutes | Docetaxel, cabazitaxel, abiraterone, enzalutamide, apalutamide, darolutamide |
The drug’s mechanism differs from modern prostate-cancer treatments. Estramustine has estrogen-mediated endocrine effects and cytotoxic activity associated with microtubule disruption and the nitrogen mustard component. Its adverse-event profile includes thromboembolic events, cardiovascular toxicity, fluid retention, gynecomastia, nausea, diarrhea, and hepatic effects, which have reduced its attractiveness relative to newer agents.[1]
When does estramustine phosphate sodium lose exclusivity?
Estramustine phosphate sodium has no meaningful remaining regulatory exclusivity in the United States. The original product approval dates to the early 1980s, placing any ordinary small-molecule patent term associated with the original product well outside the current commercial period.
The original composition and use claims, to the extent they existed, would have expired decades ago under modern patent-term calculations. Patent-term restoration under the Hatch-Waxman framework could not preserve exclusivity for a product of this age into the current market.
What is the Orange Book status of estramustine phosphate sodium?
The FDA’s Drugs@FDA records identify Emcyt under NDA 018919. Current commercial status is materially different from the product’s historical approval status. FDA records distinguish between approval, marketing status, and withdrawal from sale. A product may remain listed in FDA databases after commercial distribution has ended.
No current, commercially significant Orange Book patent or exclusivity position is associated with estramustine phosphate sodium. The product does not have a biologic exclusivity period, pediatric exclusivity period, or modern clinical-trial exclusivity relevant to market protection.[2]
Are there active formulation patents for estramustine phosphate sodium?
No active formulation patent estate with clear commercial significance has been identified in the public regulatory record for the legacy 140 mg oral capsule. Any later formulation or manufacturing patents would need to be evaluated individually by jurisdiction, claim scope, and enforceability. They would not restore the broad market exclusivity associated with a new molecular entity.
The commercial risk profile is therefore based mainly on manufacturing economics, product availability, drug-supply decisions, and regulatory compliance rather than patent exclusion.
How many patents cover estramustine phosphate sodium?
The practical answer is that no active patent portfolio currently protects the U.S. market in a way that would block generic or legacy-product competition.
Historical patent families may have covered:
- Estramustine phosphate compounds
- Pharmaceutical compositions
- Oral capsule formulations
- Methods for treating prostate cancer
- Manufacturing and purification processes
Those rights are distinct from currently enforceable market exclusivity. A historical patent count would have limited commercial value unless it included live claims, expiration dates, terminal disclaimers, maintenance-fee status, and jurisdiction-specific prosecution records.
For investors and licensing teams, the relevant conclusion is that estramustine phosphate sodium is not a patent-protected growth asset. Its value depends on supply reliability, manufacturing cost, distribution access, and the residual patient population.
What generic entry risks exist for estramustine phosphate sodium?
Generic entry risk is structurally high because:
- The product has no meaningful remaining new-drug exclusivity.
- The dosage form is an oral capsule rather than a complex biologic or delivery system.
- The active ingredient has been marketed for decades.
- Treatment alternatives have already reduced the addressable patient population.
- Clinical differentiation is weak in current prostate-cancer treatment algorithms.
Generic manufacturers would still need to address bioequivalence, product quality, stability, capsule formulation, and the regulatory requirements for an abbreviated new drug application. Those requirements create operational barriers, but they are not equivalent to patent protection.
The market may remain concentrated if expected volume is too low to justify regulatory filing, validation, pharmacovigilance, and commercial distribution. In that case, limited competition may reflect poor economics rather than legal barriers.
What generic launch scenarios are most likely?
| Scenario | Market effect | Probability assessment |
|---|---|---|
| No new generic entrant | Product remains a low-volume legacy medicine | Plausible because of limited demand |
| One generic entrant | Price pressure and possible originator withdrawal | Commercially likely if demand remains stable |
| Multiple generic entrants | Rapid price erosion and distribution consolidation | Less likely unless demand is materially higher |
| Product discontinuation | Patients shift to alternative therapies or limited-source supply | Material risk |
| Specialty-retailer continuation | Stable but small market with restricted distribution | Plausible |
The most important launch risk is not a court-ordered generic date. It is the possibility that a manufacturer exits because revenue does not justify continued production.
Which companies are challenging estramustine phosphate sodium?
No major current Paragraph IV litigation campaign has been identified as a central market event for estramustine phosphate sodium. Paragraph IV litigation is more relevant to active, commercially important branded products with valuable remaining patents. Estramustine’s age and limited demand reduce the incentive for a high-profile patent challenge.
Generic competition, where present, is more likely to proceed through ordinary abbreviated-application pathways after patent expiration rather than through commercially consequential litigation.
What patent litigation affects estramustine phosphate sodium?
No current high-value U.S. patent litigation materially affecting the product’s market has been identified. The absence of litigation is itself consistent with the product’s low commercial value and weak remaining exclusivity.
There is no known settlement framework comparable to the reverse-payment agreements associated with major branded oncology products. No settlement date or authorized generic arrangement has a material public-market role in the product’s current economics.
What is the FDA regulatory status of estramustine phosphate sodium?
The product has historical FDA approval for prostate cancer, but its commercial availability has been limited and its relevance has declined. FDA databases should be read carefully because a discontinued marketing status does not automatically mean that the FDA withdrew approval for safety or efficacy reasons.
The drug’s regulatory position is best characterized as an old approved oncology product with limited present-day commercial momentum. Its label reflects a treatment era in which estrogenic agents and older hormonal chemotherapies had a larger role in prostate cancer management.[1]
Does estramustine phosphate sodium have biosimilar risk?
No. Biosimilars apply to biological products, not conventional small-molecule drugs such as estramustine phosphate sodium. Competitive pressure comes from generic versions and therapeutic substitutes.
The more important competitive threat is substitution by newer prostate-cancer therapies, including:
- Abiraterone acetate
- Enzalutamide
- Apalutamide
- Darolutamide
- Docetaxel
- Cabazitaxel
- Radium-223 in selected disease settings
- Lutetium-based radioligand therapy in eligible patients
How does estramustine compare with modern prostate-cancer drugs?
| Product | Treatment role | Commercial position | Competitive effect on estramustine |
|---|---|---|---|
| Estramustine | Legacy oral cytotoxic-hormonal therapy | Mature, limited market | Baseline product |
| Docetaxel | Established chemotherapy | Broad guideline-supported use | Strong substitute |
| Cabazitaxel | Later-line taxane | Specialty oncology market | Strong substitute after docetaxel |
| Abiraterone | Androgen synthesis inhibitor | Large historical commercial market | Major substitute |
| Enzalutamide | Androgen-receptor inhibitor | Large commercial market | Major substitute |
| Apalutamide | Androgen-receptor inhibitor | Earlier-disease and advanced-disease use | Strong substitute |
| Darolutamide | Androgen-receptor inhibitor | Growing, differentiated use | Strong substitute |
Modern agents offer better integration with contemporary treatment sequencing, more substantial clinical-development programs, and stronger commercial support. Estramustine is usually considered only when standard therapies are unsuitable, unavailable, or exhausted.
The product’s estrogenic adverse effects and thromboembolic risk are important disadvantages. Newer agents also carry serious toxicities, but their evidence base and treatment positioning are substantially stronger.[3]
What is the financial trajectory for estramustine phosphate sodium?
No reliable public filing series reports standalone global revenue for estramustine phosphate sodium. Pfizer and its predecessor companies historically reported products within broad pharmaceutical segments, without separating revenue for this product.
The financial trajectory can therefore be assessed through market structure rather than precise annual sales:
| Period | Commercial trajectory |
|---|---|
| 1980s | Established oncology product with a differentiated role in advanced prostate cancer |
| 1990s | Mature product facing emerging chemotherapy and hormonal alternatives |
| 2000s | Declining strategic relevance as docetaxel and newer therapies expanded |
| 2010s | Niche or salvage use; reduced physician adoption |
| 2020s | Limited-market legacy product with weak growth prospects and supply risk |
What drives revenue exposure?
Revenue exposure is affected by:
- The shrinking eligible patient population
- Guideline displacement
- Availability of lower-cost alternatives
- Manufacturer decisions about continued production
- Generic substitution
- Hospital and specialty-pharmacy formulary policies
- Treatment sequencing in metastatic castration-resistant prostate cancer
- Supply interruptions and inventory levels
Estramustine does not have the characteristics of a late-life branded product capable of generating durable pricing power. Any remaining revenue is likely to be concentrated in a small number of markets and distributors.
Is estramustine phosphate sodium commercially attractive for licensing?
The asset has limited licensing appeal as a standalone product. A potential transaction would be more likely to focus on:
- Acquisition of a niche oncology product line
- Rights in a market with limited local competition
- Manufacturing or distribution rights
- Portfolio rationalization
- Access to an established regulatory file
- Supply continuity for a small patient population
A royalty-based transaction would face a low ceiling unless the license included multiple oncology products or a broader geographic territory. The absence of meaningful exclusivity limits the ability to defend premium pricing.
What manufacturing and intellectual-property barriers exist?
Manufacturing barriers are moderate rather than high. The product requires control of active-ingredient quality, capsule content uniformity, stability, packaging, and supply-chain compliance. The combination of a cytotoxic component and estrogenic pharmacology may increase handling and quality-control requirements.
The main barriers are economic:
- Low forecast demand
- Limited prescriber adoption
- Small commercial inventory requirements
- Regulatory maintenance costs
- Pharmacovigilance obligations
- Risk of abrupt market contraction
- Competition from established alternative therapies
No complex biologic manufacturing process, device platform, or delivery technology creates a durable barrier to entry.
What is the likely future of the estramustine phosphate sodium market?
The market is likely to remain small and fragmented. Three outcomes are commercially plausible: continued limited supply by a legacy or specialty manufacturer, replacement by generic supply, or full withdrawal as demand falls below an economic production threshold.
A significant market rebound is unlikely without a new clinical use, a reformulated product with improved tolerability, or evidence establishing a role in a treatment setting where modern therapies are inaccessible. None of those growth drivers is evident in the established regulatory and clinical record.
Key Takeaways
- Estramustine phosphate sodium is a legacy oral treatment for metastatic or progressive prostate cancer.
- Its original patent and regulatory exclusivity period expired long ago.
- No current patent estate appears capable of blocking generic competition in the United States.
- Paragraph IV litigation and settlement activity do not represent material current market events.
- Biosimilar competition is irrelevant because estramustine is a small molecule.
- The principal commercial threats are therapeutic substitution, low demand, generic entry, and manufacturer discontinuation.
- Public filings do not disclose standalone estramustine revenue, preventing a reliable product-level sales estimate.
- The product has limited licensing value unless bundled with manufacturing rights, geographic exclusivity, or a broader oncology portfolio.
- The market’s likely trajectory is flat to declining, with supply continuity more important than growth.
FAQs
Is estramustine phosphate sodium still approved by the FDA?
Estramustine phosphate sodium has historical FDA approval under NDA 018919 for metastatic and progressive prostate carcinoma. Current commercial availability and marketing status should be distinguished from the existence of the historical approval record.
Is Emcyt still sold in the United States?
Emcyt has had limited U.S. commercial availability, and its status has been affected by manufacturer and supply decisions. FDA database listing does not establish continuous commercial distribution.
Can a generic company launch estramustine phosphate sodium without a Paragraph IV lawsuit?
Yes. Because the product’s original exclusivity and patent protection are long expired, a generic applicant may be able to pursue an abbreviated approval pathway without triggering a commercially significant Paragraph IV dispute.
What is the biggest commercial risk for estramustine phosphate sodium?
The largest risk is product discontinuation caused by low demand and unfavorable manufacturing economics. Therapeutic substitution by androgen-receptor inhibitors and taxane chemotherapy compounds that risk.
Is estramustine phosphate sodium used in first-line prostate-cancer treatment?
No. It is not a mainstream first-line treatment in contemporary prostate-cancer practice. Its use is generally limited by the availability of better-supported and more widely adopted therapies.
References
-
Pfizer Inc. (n.d.). Emcyt (estramustine phosphate sodium) capsules: U.S. prescribing information. U.S. Food and Drug Administration. https://www.accessdata.fda.gov/drugsatfda_docs/label/
-
U.S. Food and Drug Administration. (n.d.). Drugs@FDA: FDA-approved drugs. https://www.accessdata.fda.gov/scripts/cder/daf/
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National Comprehensive Cancer Network. (2024). NCCN clinical practice guidelines in oncology: Prostate cancer. https://www.nccn.org/guidelines/guidelines-detail?category=1&id=1459
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