CLINICAL TRIALS PROFILE FOR EZOGABINE

All Clinical Trials for Ezogabine

Trial ID	Title	Status	Sponsor	Phase	Start Date	Summary
NCT01332513 ↗	An Open Label, Randomised, Repeat Dose Study to Assess the Pharmacokinetic Performance of Five Ezogabine/Retigabine Modified Release (MR) Formulations at Steady State Compared to the Immediate Release (IR) Formulation.	Completed	GlaxoSmithKline	Phase 1	2011-02-10	This is an open-label, single centre, repeat dose, up- titration study in healthy male and female subjects to assess the pharmacokinetic (PK) performance of five prototypes of ezogabine modified release tablet formulations. The study will consist of a screening period, a treatment phase (consisting of a titration phase, bioavailability phase and food effect phase) and a post-treatment follow-up visit. The study duration from screening to follow up will be approximately 7 weeks. No study procedures will start before informed consent is obtained. Subjects will remain in the clinical unit for the duration of the treatment period (35 days). Subjects will receive repeat doses of ezogabine for up to 34 days starting at a dose of 100 mg IR TID (300mg TDD) with a standard meal (to be consumed 30 min prior to dosing) for Days 1-3, on days 4-6 subjects will receive 150mg IR TID (450mg TDD). On Day 7 through to the end of the study subjects will receive ezogabine (Mr or IR) at a dose of 600mgTDD. On Day 7 subjects will enter into a 6-way cross over period to investigate the 5 MR formulations being tested (each at 300mg BID) and the single IR formulation (at 200mg TID). Subjects will receive each formulaition for 4 days and blood samples for pharmacokinetic analysis will be collected up to 24 hours post dose on each 4th day (PK days). On Day 31 subjects will enter into a food effect phase to investigate the 5 MR formulations being tested (each at 600mg QD). Subjects in this period will have a PK day on Day 33 (following a standard breakfast), and on Day 34 (following a high fat breakfast) to investigate a food effect on the PK profile of ezogabine.
NCT01462656 ↗	Risk of Urinary Retention With Retigabine	Terminated	GlaxoSmithKline		2011-02-01	A prospective cohort study of antiepileptic drug (AED) polytherapy-treated epilepsy patients within the HealthCore Integrated Research Database (HIRD) will be conducted. Following the launch of Ezogabine (EZG), patients initiating a new AED polytherapy regimen will be followed until the earliest of an episode of urinary retention (UR), change in their AED regimen, end of follow-up, or end of study (when the specified sample size of EZG AED polytherapy users has been attained). After the end of study, the incidence of UR during exposures to EZG and non-EZG AED polytherapies will be compared. Polytherapy will be defined as treatment regimen containing at least two different AEDs. A prospective cohort study of patients who receive EZG under circumstances not indicated in the product label within the HIRD will also be conducted. Following the launch of EZG, epilepsy patients initiating AED monotherapy with EZG as well as non-epilepsy patients initiating EZG for another disease will be followed until the earliest of an episode of UR, change in their AED regimen (if applicable), end of follow-up, or end of study. The incidence of UR during exposure to EZG under circumstances not indicated in the product label will be described. A descriptive analysis of the patients will also be included. To meet the other secondary objective, non-EZG AED monotherapy users will be identified in the prospective cohort and incidence of UR will be calculated to determine if there is a difference in UR risk between monotherapy and polytherapy AED use.
NCT01462669 ↗	Crossover Study to Evaluate the Pharmacokinetics of Ezogabine/Retigabine in Taiwanese Subjects	Completed	GlaxoSmithKline	Phase 1	2012-04-10	The purpose of this study is to investigate the pharmacokinetics of single oral doses of ezogabine/retigabine and the primary metabolite (NAMR) in healthy male and female Taiwanese volunteers. Subjects will receive four separate doses of ezogabine/retigabine tablets: 50 mg, 100 mg, 200 mg and 400 mg administered once orally. Blood samples will be obtained at pre-defined timepoints over the duration of the study to determine the concentration of ezogabine/retigabine and NAMR. Safety assessments will include measurements of vital signs, collection of adverse events, clinical laboratory tests and the Columbia Suicide Severity Rating Scale.
NCT01480609 ↗	Effect of Haemodialysis on the Pharmacokinetics of Ezogabine/Retigabine and Its N-acetyl Metabolite	Completed	GlaxoSmithKline	Phase 1	2011-11-30	This in an open-label, single dose, fixed sequence, two treatment period study enrolling 8 patients (to obtain 6 evaluable) with end stage renal disease (ESRD) receiving haemodialysis. Patients will remain in the unit during each treatment period from admission to the collection of the final PK sample. The doses of ezogabine/retigabine in the two treatment periods will be separated by at least 7 days.
NCT01494584 ↗	Study in Pediatric Subjects With Epilepsy	Terminated	Bausch Health Americas, Inc.	Phase 2	2012-07-25	This is an open-label study to evaluate the pharmacokinetics, safety and tolerability of ezogabine/retigabine in subjects aged 12 years to less than 18 years with uncontrolled partial onset seizures or Lennos-Gastaut syndrome.

Clinical Trial Conditions for Ezogabine

Condition Name

Condition Name for Ezogabine
Intervention	Trials
Epilepsy	12
Nervous System Diseases	2
Brain Diseases	2
Central Nervous System Diseases	2

Condition MeSH

Condition MeSH for Ezogabine
Intervention	Trials
Epilepsy	11
Seizures	4
Depressive Disorder	2
Depression	2

Clinical Trial Locations for Ezogabine

Trials by Country

Trials by Country for Ezogabine
Location	Trials
United States	56
Australia	3
Poland	1
France	1
Belgium	1

Trials by US State

Trials by US State for Ezogabine
Location	Trials
Maryland	6
Texas	5
Florida	5
California	5
New York	4

Clinical Trial Progress for Ezogabine

Clinical Trial Phase

Clinical Trial Phase for Ezogabine
Clinical Trial Phase	Trials
Phase 4	3
Phase 3	4
Phase 2	4

Clinical Trial Status

Clinical Trial Status for Ezogabine
Clinical Trial Phase	Trials
Completed	8
Terminated	6
Recruiting	2

Clinical Trial Sponsors for Ezogabine

Sponsor Name

Sponsor Name for Ezogabine
Sponsor	Trials
GlaxoSmithKline	11
Bausch Health Americas, Inc.	3
Valeant Pharmaceuticals International, Inc.	3

Sponsor Type

Sponsor Type for Ezogabine
Sponsor	Trials
Industry	20
Other	10
NIH	1

Ezogabine (Retigabine) Clinical Trials Update and Market Projection: Pipeline Status, Exclusivity Timing, and Competitive Risks

Last updated: May 25, 2026

Ezogabine (also known as retigabine) is not an active FDA-listed product in the US and has no current, commercially scaled market trajectory. Clinical development has stalled and the compound’s global commercialization and lifecycle are constrained by regulatory history and substitution by other antiepileptics. As a result, market projection is dominated by historical phase and regulatory outcomes rather than an ongoing late-stage program.

What is the current clinical trial status of ezogabine (retigabine)?

Answer: Ezogabine’s development is effectively discontinued; there is no active late-stage (Phase 3) program driving new regulatory submissions in recent years.

Are there any active Phase 3 or FDA-directed trials for ezogabine?

No identifiable ongoing Phase 3 trials and no current FDA-facing late-stage program were established through the post-market era referenced for ezogabine/retigabine. Published clinical development for this asset is largely historical, centered on efficacy and dose-ranging studies for focal seizures.

What types of studies defined ezogabine’s clinical package?

Ezogabine’s core clinical evidence set was built around:

• Adjunctive therapy in focal seizures (partial-onset seizures)
• Dose-ranging and titration strategies
• Safety monitoring for dose-limiting toxicities that later became central to benefit-risk reviews

What safety signals drove the regulatory and development endpoint?

Key safety issues reported for ezogabine/retigabine included:

• Central nervous system adverse events (dizziness, somnolence, confusion)
• Psychiatric and cognitive adverse events (including depression-related findings)
• Potential for pigmentary changes (e.g., retinal and skin pigmentation) and QT-related considerations reported in the program

(These issues are consistent with the regulatory rationale that ultimately limited continued availability in at least some jurisdictions and reduced the commercial runway.)

What market did ezogabine reach, and why did adoption stall?

Answer: Ezogabine’s market penetration was constrained by regulatory outcomes and safety risk management. Use did not scale into a durable, high-volume franchise.

How did regulatory history affect commercial viability?

Ezogabine entered clinical practice in certain regions after approval, but continued availability and scale were limited by safety concerns that were significant enough to drive later withdrawals/restrictions in the European Union and the US.

What is the realistic commercial ceiling for ezogabine under current conditions?

Given the absence of an active product lifecycle in the US market and no ongoing late-stage development pipeline, the realistic “market projection” for ezogabine is effectively zero for new commercial revenue. The credible market is confined to:

• Residual legacy use where supply exists (limited and non-expansionary)
• Generic/withdrawn access depending on local history
• Historical monetization rather than forward sales

When does ezogabine lose exclusivity, and what does that mean for generic entry risks?

Answer: Forward generic launch risk is not a standard framework for ezogabine because the drug is not an actively marketed US product and clinical development is discontinued.

What matters more than patent exclusivity for ezogabine?

For non-line-extensible assets like ezogabine, market entry risk is driven by:

• Whether an approved reference product remains on market in a major jurisdiction
• Whether existing regulatory listings persist and whether any authorized generics are marketed
• Whether there is an active regulatory bridge that can restart approvals

How do patent estates usually factor when commercialization is suspended?

Even if patents expire, the absence of an active marketed product typically reduces practical incentives for generic entry absent a restart. Litigation and Paragraph IV incentives generally follow commercial viability.

What is the Orange Book status of ezogabine?

Answer: Ezogabine is not positioned as a current US FDA-listed reference drug for ongoing generic/ANDA competition in the normal way.

Does ezogabine still have an Orange Book listing that enables generic competition?

In a typical scenario, a generic applicant relies on an FDA reference product listing. For ezogabine, forward-looking generic competition is not present as an ongoing competitive event comparable to active CNS franchises.

What formulation patents protect ezogabine, and do they affect availability?

Answer: Formulation IP would typically be relevant only if the product is being reintroduced or if a generic seeks approval against a still-marketed reference.

Why formulation IP does not drive near-term availability

Where commercialization is stalled, formulation patents do not create near-term revenue opportunity unless:

• The sponsor re-launches and files new regulatory submissions
• Another party seeks to reconstitute supply via a formal regulatory pathway

What method-of-use or dosing patents could matter for ezogabine?

Answer: Method-of-use and dosing patents matter only if there is an active path to regulatory approval for a new label.

How the label history changes the patent strategy

Because ezogabine’s development is discontinued, method-of-use exclusivity does not translate into market growth.

Which companies held ezogabine’s rights, and how does ownership affect licensing?

Answer: Ezogabine/retigabine is associated with historical development by major pharma that advanced the molecule into approval. Licensing prospects are limited by discontinued development, regulatory availability, and the lack of a current commercialization platform.

What patent litigation affects ezogabine?

Answer: Ezogabine does not currently present a patent-litigation pattern that is comparable to other actively marketed antiepileptics (e.g., modern patent estate disputes tied to Paragraph IV filings and ANDA entries).

How does ezogabine compare with competing drugs for focal seizures in market adoption?

Answer: Ezogabine’s commercial adoption did not compete effectively against established focal seizure therapies with stronger continuing market penetration.

Competitive set that dominates focal seizure treatment

Modern focal seizure landscapes are shaped by:

• Brand and generic entrants in first-line and add-on CNS epilepsy segments
• Newer mechanisms and better-tolerability profiles that reduced the relative willingness to use ezogabine in routine practice

Why ezogabine lost competitive share

Regulatory and safety risk drove restricted adoption versus continued expansion of competing therapies.

Clinical trials timeline: what were the key ezogabine milestones?

Answer: Ezogabine’s clinical arc is historical, with dose-ranging/adjunctive efficacy trials followed by approval and then constrained availability due to safety-driven regulatory actions.

High-level timeline (development to regulatory constriction)

• Clinical program development and phase evaluations in focal seizures
• Approval in certain jurisdictions
• Safety-driven regulatory constraints leading to restriction/withdrawal patterns
• Development effectively stops, with no ongoing late-stage pipeline defining the future

(A precise date-by-date milestone list requires validated trial-level sourcing; without that, the timeline is limited to the program arc.)

What is the most plausible market projection for ezogabine through 2030?

Answer: Zero incremental growth is the only defensible projection under current conditions.

Projection table

Scenario	Key assumption	Incremental US revenue outlook	EU/other markets outlook	Probability
Continued absence of re-launch	No active regulatory pathway and no late-stage program	$0	$0 to minimal legacy-only	High
Legacy residual supply	Limited continued access where any supply remains	$0	Low single-digit millions locally (if at all)	Medium-low
Re-launch via new data	New clinical program and regulatory submissions	Not supported by current pipeline	Not supported by current pipeline	Low

What regulatory pathway would be required to restart ezogabine’s life cycle?

Answer: A restart would require new clinical evidence adequate to re-establish benefit-risk, then new regulatory review and potential label repositioning.

Why a simple “switch” is unlikely

Ezogabine’s prior safety profile issues limit the likelihood that regulators would accept a minimal-change re-introduction without a substantial evidence package.

Key takeaways

• Ezogabine’s clinical development is effectively discontinued, with no active late-stage program driving forward regulatory milestones.
• Market projection is dominated by regulatory withdrawal/restriction history and absence of current commercialization, not by future exclusivity timelines.
• Orange Book-style generic competition dynamics do not apply as an ongoing forward event for ezogabine because the drug is not positioned as an active US reference product.
• Competitive share is structurally displaced by modern focal seizure therapies with continuing market penetration.
• The only realistic forward financial outlook is flat to zero incremental revenue through 2030.

FAQs

1. Is ezogabine currently available in the US and EU?
2. What adverse events most limited ezogabine’s continued clinical use?
3. Are there any remaining ezogabine clinical trials registered today?
4. Does ezogabine have an FDA-approved label for focal seizures as of today?
5. What alternatives best substitute for ezogabine in focal seizure add-on therapy?

References

1. FDA (US). Orange Book: Approved Drug Products with Therapeutic Equivalence Evaluations. FDA.gov.
2. ClinicalTrials.gov. Ezogabine (retigabine) search results and study records.
3. EMA (European Medicines Agency). Public assessment history and product information for retigabine-related decisions.