Ethosuximide - Generic Drug Details

What are the generic sources for ethosuximide and what is the scope of patent protection?

Ethosuximide is the generic ingredient in two branded drugs marketed by Bionpharma, Epic Pharma Llc, Heritage Pharms Inc, Onesource Specialty, Puracap Pharm Llc, Parke Davis, Chartwell Rx, Pharm Assoc, Teva Pharms, and Parke-davis, and is included in ten NDAs. Additional information is available in the individual branded drug profile pages.

There is one drug master file entry for ethosuximide. Nine suppliers are listed for this compound.

Summary for ethosuximide

US Patents:	0
Tradenames:	2
Applicants:	10
NDAs:	10
Drug Master File Entries:	1
Finished Product Suppliers / Packagers:	9
Raw Ingredient (Bulk) Api Vendors:	94
Clinical Trials:	12
Drug Prices:	Drug price trends for ethosuximide
What excipients (inactive ingredients) are in ethosuximide?	ethosuximide excipients list
DailyMed Link:	ethosuximide at DailyMed

See drug prices for ethosuximide

Recent Clinical Trials for ethosuximide

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

Sponsor	Phase
Johns Hopkins University	Phase 3
Tanta University	Phase 3
Zhejiang University	Early Phase 1

See all ethosuximide clinical trials

Pharmacology for ethosuximide

Drug Class	Anti-epileptic Agent
Physiological Effect	Decreased Central Nervous System Disorganized Electrical Activity

Medical Subject Heading (MeSH) Categories for ethosuximide

Anticonvulsants

Anatomical Therapeutic Chemical (ATC) Classes for ethosuximide

N03AD	Succinimide derivatives
N03A	ANTIEPILEPTICS
N03	ANTIEPILEPTICS
N	Nervous system

US Patents and Regulatory Information for ethosuximide

Applicant	Tradename	Generic Name	Dosage	NDA	Approval Date	TE	Type	RLD	RS	Patent No.	Patent Expiration	Product	Substance	Delist Req.	Exclusivity Expiration
Parke Davis	ZARONTIN	ethosuximide	CAPSULE;ORAL	012380-001	Approved Prior to Jan 1, 1982	AB	RX	Yes	Yes
Epic Pharma Llc	ETHOSUXIMIDE	ethosuximide	CAPSULE;ORAL	040686-001	May 28, 2008	AB	RX	No	No
Teva Pharms	ETHOSUXIMIDE	ethosuximide	SYRUP;ORAL	081306-001	Jul 30, 1993		DISCN	No	No
Heritage Pharms Inc	ETHOSUXIMIDE	ethosuximide	CAPSULE;ORAL	200892-001	Sep 25, 2012	AB	RX	No	No
Bionpharma	ETHOSUXIMIDE	ethosuximide	CAPSULE;ORAL	040430-001	Oct 28, 2002	AB	RX	No	No

Market Dynamics and Financial Trajectory for Ethosuximide

Last updated: July 28, 2025

Introduction

Ethosuximide, a succinimide derivative, is a well-established antiepileptic drug primarily indicated for absence seizures. Since its introduction in the 1960s, ethosuximide has maintained a niche yet critical role within neurological therapeutics. With evolving market dynamics driven by advances in epilepsy management, emerging competitors, and genomic medicine, understanding the drug's current economic position and future trajectory is vital for stakeholders in the pharmaceutical industry.

Pharmacological Profile and Clinical Utility

Ethosuximide's mechanism involves blocking T-type calcium channels within the thalamic neurons, reducing hypersynchronous neuronal firing characteristic of absence seizures (1). Its efficacy, safety profile, and longstanding clinical use have cemented its status as a first-line therapy for absence seizures, especially in pediatric populations. However, newer drugs with improved side-effect profiles and broader spectrum activity have emerged, influencing market dynamics.

Current Market Landscape

Market Size and Penetration

Global utilization of ethosuximide remains constrained, with estimates suggesting a modest market share within the anti-epileptic drugs (AEDs) segment. The prevalence of absence seizures, approximately 10-15% of pediatric epilepsy cases (2), establishes a consistent demand, but the dominance of newer agents like lamotrigine, levetiracetam, and valproate has marginally reduced ethosuximide's market share (3).

Pricing and Reimbursement

Being an off-patent, generic medication, ethosuximide benefits from low manufacturing costs and competitive pricing. Insurance coverage and healthcare policies in major markets such as the United States and Europe favor affordability. The drug's established safety profile lends to steady prescription rates but limits pricing power, typically relegating revenues to modest levels in comparison to innovative therapies.

Regulatory and Patent Status

Ethosuximide's patent expired decades ago, leaving the market open for generic manufacturers. Regulatory pathways are straightforward, with broad approval since the 1960s. Consequently, the drug faces minimal barriers to entry but also limited incentives for formulation improvements or new indications.

Emerging Market Trends and Drivers

Burgeoning Epilepsy Diagnostics and Awareness

Increased awareness and diagnostic capabilities have led to earlier detection of epilepsy syndromes, including absence seizures. This trend sustains a baseline demand for core treatments like ethosuximide, especially in developing regions where access to cutting-edge therapies remains limited.

Innovations in AEDs

The advent of novel AEDs offering broader efficacy, fewer side effects, and once-daily dosing options has redistributed prescribing patterns. For instance, medications like ethosuximide are increasingly used adjunctively or as second-line agents rather than first-line therapy in some cases, diminishing revenue streams.

Generic Competition and Price Competition

The influx of generic ethosuximide formulations has driven price competition, pressuring profit margins. While this makes the drug accessible, it constrains revenue growth for existing manufacturers.

Regulatory and Market Challenges

Stringent regulatory standards for manufacturing quality and bioequivalence in emerging markets can impact supply chains and product availability. Additionally, the evolving landscape favors newer agents with proven advantages in tolerability or efficacy, which further constrains ethosuximide's competitive position.

Financial Trajectory and Future Outlook

Revenue Projections

Considering the factors above, ethosuximide's revenue trajectory is projected to remain relatively flat or experience slight decline over the next five years. The global epilepsy drug market size is anticipated to grow at a compound annual growth rate (CAGR) of 4-5% (4), but this growth predominantly stems from newer medications rather than traditional agents like ethosuximide.

Potential Growth Areas

Despite limited prospects in developed markets, niche opportunities exist in developing regions with limited access to newer therapies. Ethosuximide's low cost renders it an attractive option where healthcare budgets are constrained. Additionally, potential formulation innovations—such as sustained-release versions—could enhance patient compliance, offering incremental revenue opportunities.

Impact of Biosimilars and Generics

The widespread generic availability limits pricing power and margins but stabilizes volumes and ensures consistent revenue streams. Industry consolidation and increased manufacturing efficiency may further suppress costs, maintaining ethosuximide's attractiveness to budget-sensitive healthcare systems.

Research and Development Opportunities

Limited ongoing research targets ethosuximide specifically; however, repurposing or combination therapies could expand its utility. Any such developments would require substantial investment and regulatory approval processes, with uncertain returns given the competitive landscape.

Conclusion

Ethosuximide occupies a stable but niche position within the epilepsy treatment paradigm. Market dynamics favor low-cost, generic-based use aligned with global demand rather than aggressive revenue growth. The drug's financial trajectory is expected to remain modest, shaped by competitive pressures, offering steady revenues primarily in developing economies. Its future hinges on regional needs, formulation enhancements, and potential repositioning rather than blockbuster growth.

Key Takeaways

• Niche Market: Ethosuximide remains the first-line treatment for absence seizures but faces competition from newer AEDs with better tolerability profiles.
• Generic Competition: Widespread generic availability limits profit margins but sustains widespread accessibility.
• Growth Constraints: Limited innovation and patent expiries restrict significant revenue expansion; growth is predominantly regional and incremental.
• Market Opportunities: Developing regions and formulation innovations provide opportunities for sustained demand.
• Strategic Considerations: Manufacturers should focus on cost efficiencies, regional access, and potential repurposing to optimize long-term returns.

FAQs

1. Is ethosuximide still a preferred treatment for absence seizures?
Yes. Ethosuximide remains a first-line therapy for typical absence seizures due to its proven efficacy and safety profile, particularly in pediatric populations.

2. How does generic competition impact ethosuximide's market revenue?
Generic manufacturing reduces prices and profit margins but helps maintain steady demand due to affordability and widespread clinical acceptance.

3. Are there any new formulations of ethosuximide in development?
Currently, no significant novel formulations are in late-stage development; most efforts focus on brand reinforcement and regional access expansion.

4. Can ethosuximide be repurposed for other neurological indications?
Research on repurposing is limited; while theoretically possible, no significant clinical trials or regulatory approvals for alternative indications exist at present.

5. What factors could influence ethosuximide's market in the coming years?
Advancements in epilepsy therapies, regulatory changes, regional healthcare policies, and formulation innovations could shape its market trajectory.

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Sources:

1. Kumar, A., & Singh, A. (2018). Mechanism of action of ethosuximide in absence epilepsy. Epilepsy Research and Treatment.
2. Fisher, R. S., et al. (2014). The new classification of seizures and epilepsy. Epilepsia.
3. WHO. (2020). Epilepsy: a public health imperative.
4. MarketWatch. (2022). Global anti-epileptic drugs market size and growth outlook.