List of Excipients in Branded Drug ETHACRYNIC ACID

Generic Drugs Containing ETHACRYNIC ACID

Company	Ingredient	NDC	Excipient
West-Ward Pharmaceuticals Corp	ethacrynic acid	0054-0415	LACTOSE MONOHYDRATE
West-Ward Pharmaceuticals Corp	ethacrynic acid	0054-0415	MAGNESIUM STEARATE
West-Ward Pharmaceuticals Corp	ethacrynic acid	0054-0415	SILICON DIOXIDE

What are the Most Frequently-Used Excipients in ETHACRYNIC ACID?

# Of NDCs	Excipient
7	CALCIUM STEARATE
1	CELLULOSE, MICROCRYSTALLINE
1	CROSPOVIDONE

Ethacrynic Acid Excipient Strategy and Commercial Opportunities

Last updated: August 16, 2026

Ethacrynic acid is an off-patent loop diuretic with limited competition, a differentiated non-sulfonamide structure, and formulation challenges driven by low aqueous solubility, dose-related gastrointestinal effects, and ototoxicity risk. The strongest commercial opportunities are not basic tablet generics alone. They are improved oral formulations, sodium-free or low-sodium presentations, hospital-ready liquid or injectable products, and 505(b)(2) products supported by bioavailability or tolerability improvements.

What is the FDA status of ethacrynic acid?

Ethacrynic acid is an FDA-approved loop diuretic marketed orally as Edecrin tablets at 25 mg. It is used to treat edema associated with congestive heart failure, hepatic disease, renal disease, and other conditions requiring potent diuresis. Unlike furosemide, bumetanide, and torsemide, ethacrynic acid does not contain a sulfonamide group. That distinction makes it clinically relevant for some patients with serious sulfonamide hypersensitivity concerns.[1]

Attribute	Ethacrynic acid
Active ingredient	Ethacrynic acid
Therapeutic class	Loop diuretic
Principal dosage form	Immediate-release oral tablet
Reference strength	25 mg
FDA route	Oral
Brand	Edecrin
Key differentiation	Non-sulfonamide loop diuretic
Main formulation issue	Low water solubility and dose-related tolerability
Main commercial market	Hospital, cardiology, nephrology, and specialty pharmacy
Regulatory pathways for new products	ANDA or 505(b)(2), depending on product design

FDA labeling identifies ethacrynic acid as a potent diuretic with risks including dehydration, electrolyte depletion, hypotension, gastrointestinal reactions, and ototoxicity. The product label recommends lower initial doses in some populations and warns against rapid intravenous administration of ethacrynate sodium because of ototoxicity risk.[1]

What excipients are used in ethacrynic acid tablets?

The commercial tablet uses conventional oral solid-dose excipients. Public product labeling identifies excipient classes including lactose, corn starch, povidone, magnesium stearate, and sodium starch glycolate.[2] Exact excipient composition can vary by manufacturer, label version, and manufacturing site.

The formulation logic is conventional:

Excipient class	Likely function	Commercial relevance
Lactose	Diluent and tablet mass builder	Creates a potential route for lactose-free positioning
Corn starch	Diluent and disintegrant	Supports low-cost immediate release
Povidone	Binder	Controls granule strength and manufacturability
Sodium starch glycolate	Superdisintegrant	Supports tablet breakup and dissolution
Magnesium stearate	Lubricant	Reduces tooling and ejection problems

The current excipient platform is suitable for an inexpensive immediate-release tablet, but it leaves room for differentiated products. The most defensible improvements would address dissolution, excipient sensitivity, dose flexibility, and hospital administration rather than simply substitute one standard filler for another.

Which excipient strategies have the strongest commercial potential?

1. Lactose-free immediate-release tablets

A lactose-free product could target patients with lactose intolerance, hospitals seeking simplified formulary choices, and manufacturers that want to reduce dependence on dairy-derived excipients. Mannitol, microcrystalline cellulose, dibasic calcium phosphate, or partially pregelatinized starch could replace lactose, subject to compatibility and dissolution testing.

The opportunity is commercially credible but limited. Lactose-free positioning alone is unlikely to justify a large premium because multiple low-cost excipient combinations can produce equivalent tablets. Patent value would depend on a narrow, non-obvious combination tied to a measurable performance benefit, such as improved dissolution after storage or reduced tablet weight.

2. Direct-compression formulations

Ethacrynic acid tablets could be redesigned for direct compression using microcrystalline cellulose, silicified microcrystalline cellulose, spray-dried mannitol, or co-processed excipients. Direct compression could reduce granulation steps, solvent exposure, and manufacturing cost.

The technical risks are content uniformity, poor flow at a low 25 mg dose, lubricant sensitivity, and dissolution variability. A formulation patent would need more than a standard direct-compression composition. Useful claim features could include:

• Defined particle-size distribution of ethacrynic acid
• Specific drug-to-filler ratio
• Controlled tablet hardness and disintegration
• Dissolution performance across pH conditions
• Stability under high humidity
• Reduced degradation during compression or storage

3. Amorphous or particle-engineered ethacrynic acid

Ethacrynic acid has limited water solubility. Particle-size reduction, spray drying, hot-melt processing, or amorphous solid dispersion technology could increase dissolution and reduce variability in absorption.

Potential excipients include hydroxypropyl cellulose, hydroxypropyl methylcellulose, copovidone, povidone, and polymeric precipitation inhibitors. The primary risk is physical instability. An amorphous system can recrystallize during storage, especially under heat and humidity.

A commercially viable formulation would need to demonstrate a clinically meaningful benefit. Dissolution improvement alone may not be sufficient. More valuable outcomes would include:

• Lower pharmacokinetic variability
• Faster onset of diuresis
• Reduced food effect
• Smaller tablet size
• Lower dose requirement
• Better performance in patients with impaired gastrointestinal absorption

The patent estate for such a product could be stronger than a conventional excipient substitution if the formulation produces unexpected stability or exposure results.

4. Lipid-based or self-emulsifying systems

Lipid-based systems could improve apparent solubility and support liquid-filled capsules, oral solutions, or soft-gel products. Candidate components include medium-chain triglycerides, mono- and diglycerides, polysorbates, polyethylene glycol, and other pharmaceutically accepted surfactants.

This approach has a higher development burden than an immediate-release tablet. Ethacrynic acid’s acidic character, chemical stability, capsule compatibility, and taste must be evaluated. A lipid system could be attractive for patients unable to swallow tablets, but the product must establish reliable dose delivery and storage stability.

5. Taste-masked liquid formulations

A liquid formulation could expand use in pediatrics, geriatric care, feeding-tube administration, and hospital settings. The principal challenges are low solubility, acidic taste, chemical stability, and preservative selection.

Possible platforms include:

• A buffered oral suspension
• A cosolvent-based solution
• A complexed formulation using cyclodextrin
• A nanoparticulate suspension
• A powder for reconstitution

Cyclodextrin-based systems may improve apparent solubility, but the excipient level, renal clearance, and regulatory acceptability must be addressed. A suspension may be easier to develop than a clear solution, but it requires robust redispersibility, dose uniformity, sedimentation control, and container compatibility.

What formulations are protected by ethacrynic acid patents?

The original ethacrynic acid composition and early pharmaceutical patents date to the 1960s. Those foundational rights have expired. FDA’s Orange Book does not provide a meaningful current patent barrier for the basic 25 mg ethacrynic acid tablet.[3]

The relevant modern IP opportunities are formulation-specific:

Potential IP area	Patent strength	Main vulnerability
New salt or crystalline form	Medium	Prior-art and obviousness challenges
Amorphous dispersion	Medium to high	Recrystallization and routine formulation arguments
Nanoparticle formulation	Medium	Enablement and predictable-solubility arguments
Taste-masked liquid	Medium	Crowded excipient and suspension prior art
Ready-to-use injectable	Medium to high	Sterility, stability, and clinical comparability burden
Device-assisted administration	Medium	Limited market size
Simple lactose replacement	Low	Routine substitution argument
Standard tablet excipient swap	Low	Weak differentiation

A new formulation patent is more valuable when it claims a defined product profile rather than a broad list of excipients. Dissolution, particle size, impurity limits, stability, and pharmacokinetic data should support the claims.

When does ethacrynic acid lose exclusivity?

Ethacrynic acid lost its basic small-molecule exclusivity decades ago. The original product is not protected by a modern primary compound patent. Current market entry is therefore governed mainly by regulatory approval, manufacturing economics, supply reliability, and clinical differentiation.

Exclusivity type	Status
Original composition patent	Expired
Basic oral tablet protection	Expired
Current NCE exclusivity	None
Current pediatric exclusivity	None identified
Current orphan exclusivity	None identified
Current Orange Book patent barrier	No material barrier identified
Potential new formulation protection	Available only through new patentable technology

An ANDA applicant could pursue a conventional generic if an appropriate reference product and current FDA requirements are satisfied. A product with a materially different dosage form, formulation, route, or clinical rationale may require a 505(b)(2) application rather than an ANDA.[4]

What Paragraph IV challenges and generic entry risks exist?

A conventional ethacrynic acid tablet would present a low patent litigation risk because the foundational patents have expired and there is no apparent modern patent thicket surrounding the active ingredient. The primary risks are regulatory and commercial:

1. Reference-product availability and bioequivalence requirements.
2. Small market size and limited manufacturing scale.
3. Potential difficulty securing active pharmaceutical ingredient supply.
4. Low price ceilings caused by generic competition.
5. Pharmacovigilance exposure related to ototoxicity and electrolyte abnormalities.
6. Limited ability to differentiate a conventional tablet.

A Paragraph IV certification would become relevant only if an applicant targeted a product covered by a currently listed formulation or method-of-use patent. For the basic ethacrynic acid tablet, the more likely pathway is certification that no relevant patent blocks approval, rather than a high-value Paragraph IV challenge.

What FDA regulatory pathway fits new ethacrynic acid products?

ANDA pathway

An ANDA is the most economical route for a product that matches the reference product in active ingredient, dosage form, strength, route, and relevant performance characteristics. A standard 25 mg immediate-release tablet with conventional excipients would generally be evaluated as a generic product.

The ANDA opportunity is commercially constrained because the product has a narrow market and limited ability to command premium pricing.

505(b)(2) pathway

A 505(b)(2) application is more suitable for:

• Oral liquids
• New injectable presentations
• Sustained-release or modified-release products
• Bioavailability-enhanced formulations
• New salts or complexes
• Products with a clinically supported administration advantage
• Formulations intended for feeding-tube or dysphagia use

A 505(b)(2) strategy can generate market exclusivity for qualifying new clinical or formulation innovation, although the duration and scope depend on the approved product and supporting studies. It does not recreate the broad exclusivity of the original compound patent.

Hospital injectable opportunity

Historically, ethacrynate sodium has been used for parenteral administration. A modern ready-to-use or pharmacy-friendly injectable could address preparation burden, shortage risk, and dosing errors. The formulation must control pH, osmolality, chemical degradation, particulate matter, container interaction, and sterility.

Commercially attractive presentations could include:

• A premixed infusion bag
• A ready-to-dilute vial
• A dual-chamber vial
• A lyophilized vial with a dedicated diluent
• A preservative-free single-dose presentation

The principal limitation is market size. A sterile injectable may be economically viable only if it captures institutional purchasing, shortage-driven demand, or an underserved clinical niche.

How strong is the ethacrynic acid patent estate?

The underlying patent estate is weak because the compound is old and the basic oral product is long off-patent. A new sponsor would need to create a separate product estate around formulation, manufacture, packaging, or administration.

A defensible portfolio could contain:

• Composition claims covering a defined solid dispersion
• Process claims for particle engineering or granulation
• Stability claims based on impurity control
• Dosage-form claims for liquid or injectable products
• Use claims tied to a defined patient population
• Packaging claims for moisture-sensitive formulations
• Combination claims, where clinically and legally supportable

Method-of-use claims may have limited value because the principal indications are established and broad. A narrower use claim could be relevant for patients requiring a non-sulfonamide loop diuretic, but patentability and written-description issues would require careful development.

Which companies could compete with a new ethacrynic acid product?

Competition would come from three groups:

Competitor group	Examples	Competitive effect
Loop-diuretic generics	Furosemide, bumetanide, torsemide manufacturers	Strong price and formulary pressure
Branded reference product	Edecrin marketer	Establishes regulatory and clinical benchmark
Specialty generic developers	Companies focused on shortages or low-volume injectables	Potential hospital-channel competition

Furosemide remains the dominant commercial comparator because of its low cost and extensive clinical use. Torsemide competes on oral bioavailability and longer duration. Bumetanide competes on potency and dose efficiency. Ethacrynic acid retains a niche based on its non-sulfonamide structure and use in selected patients.

What licensing and partnering opportunities exist?

Ethacrynic acid is more likely to attract a formulation-development partnership than a conventional licensing deal for the active ingredient. Potential deal structures include:

• Licensing a bioavailability-enhanced oral formulation
• Contract development of a sterile injectable
• Regional commercialization rights for hospital products
• API supply agreements with dual sourcing
• Co-development with a specialty generic company
• Acquisition of a 505(b)(2) formulation platform

A partner would likely prioritize a product with one of four commercial attributes: clinical differentiation, shortage protection, hospital purchasing relevance, or a formulation patent with meaningful remaining term.

What revenue exposure supports development?

The market is niche. The largest revenue opportunity is unlikely to come from an ordinary 25 mg tablet sold into retail pharmacies. A stronger commercial model would combine:

1. A low-cost oral generic for baseline volume.
2. A premium lactose-free or swallow-friendly tablet.
3. A liquid product for institutional and special-population use.
4. A ready-to-use injectable for hospitals.
5. A formulation patent supporting price protection.

The opportunity is most attractive for a company with an existing hospital sales force, sterile manufacturing capacity, or a specialty-generic portfolio. It is less attractive for a new entrant that must build manufacturing, regulatory, and commercial infrastructure for a single low-volume product.

What are the main manufacturing and IP barriers?

Manufacturing barriers are manageable for tablets but materially higher for liquids and sterile products.

Oral solid dose barriers

• Low-dose content uniformity
• API particle-size control
• Dissolution reproducibility
• Moisture sensitivity
• Tablet compression behavior
• Supplier qualification for a low-volume API

Liquid barriers

• Solubility and precipitation
• Taste masking
• pH control
• Preservative effectiveness
• Container compatibility
• Dose uniformity after storage

Sterile product barriers

• Aseptic processing or terminal sterilization
• Particulate control
• Container closure integrity
• Dilution stability
• Light and temperature sensitivity
• Hospital preparation instructions

The strongest IP position would combine a differentiated dosage form with manufacturing know-how that is difficult to replicate. A simple excipient substitution would provide limited protection.

Key Takeaways

• Ethacrynic acid is an old, off-patent loop diuretic with no meaningful compound-level exclusivity.
• The basic 25 mg tablet is a low-risk ANDA opportunity but has limited pricing power.
• The non-sulfonamide structure provides a persistent clinical niche, particularly for selected patients with sulfonamide-related concerns.
• The highest-value excipient opportunities are lactose-free tablets, dissolution-enhanced solid dispersions, taste-masked liquids, and hospital-ready sterile products.
• A 505(b)(2) strategy is more commercially defensible than a conventional generic when the formulation provides a clear administration or exposure advantage.
• Formulation patents can be valuable, but simple filler substitution or routine tablet optimization is vulnerable to obviousness challenges.
• Commercial returns are more likely in hospital products, shortage-sensitive presentations, or differentiated specialty formulations than in an undifferentiated tablet.

FAQs

Can ethacrynic acid be formulated as an oral solution?

Yes. The principal development issues are solubility, acidic taste, chemical stability, precipitation after dilution, preservative selection, and dose uniformity. A suspension may be more practical than a clear solution.

Is a lactose-free ethacrynic acid tablet commercially attractive?

It can support a targeted product position, but lactose removal alone is unlikely to support substantial price premiums or strong patent protection. The product should pair lactose-free status with improved dissolution, smaller tablet size, or better storage performance.

Could a new ethacrynic acid injectable receive 505(b)(2) approval?

Yes, if the proposed injectable differs meaningfully from the reference product and relies partly on existing safety and efficacy information. The development package would still need to address formulation quality, sterility, stability, dosing, and labeling.

Are biosimilar risks relevant to ethacrynic acid?

No. Ethacrynic acid is a small-molecule drug, so biosimilar competition does not apply. Competition would come from generic and 505(b)(2) products.

What is the best commercial formulation for ethacrynic acid?

A hospital-ready injectable or a clinically differentiated oral formulation has greater strategic value than a conventional tablet. The best platform depends on whether the sponsor prioritizes hospital revenue, specialty pharmacy access, or low-cost generic volume.

References

1. U.S. Food and Drug Administration. (2023). Edecrin (ethacrynic acid) tablets: Prescribing information.
2. National Library of Medicine. (2024). DailyMed: Edecrin, ethacrynic acid tablet labeling.
3. U.S. Food and Drug Administration. (2024). Approved drug products with therapeutic equivalence evaluations, 44th edition.
4. U.S. Food and Drug Administration. (2024). Applications covered by section 505(b)(2).
5. U.S. Food and Drug Administration. (2024). Waiver of in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms.