TheraRadar
Data updated: May 26, 2026

HORIZANT (gabapentin enacarbil)

Trial Activity: Mature 1 active trials
CNS Approved 2011-04-06

Horizant (gabapentin enacarbil) is

Source: FDA Label • AZURITY

How HORIZANT Works

This drug works by acting as a prodrug that converts into gabapentin once inside the body. While its exact process for relieving symptoms is not fully understood, it binds strongly to the α2δ subunit of voltage-activated calcium channels. In animal studies, this activity helps prevent exaggerated responses to pain and pain caused by normally harmless stimuli.

Development Insights

Astellas Pharma Inc conducting 2 trials (40%)
3 indications explored (Focused)
restless legs syndrome (rls) (3 trials)
alzheimer disease (1 trials)
alcohol use disorder (1 trials)
3
Indications
--
Phase 3 Trials
15
Years on Market

Details

Status
Prescription
First Approved
2011-04-06
Patent Cliff
2029

Pro Metrics

Patent cliff and revenue data

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Routes
ORAL
Dosage Forms
TABLET, EXTENDED RELEASE

Companies

Active Ingredient: GABAPENTIN ENACARBIL

HORIZANT Approval History

2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
Original
New Indication
New Form
Label Update
22 FDA actions from 2011 to 2025 · 2 indication expansions
Apr 2025 SUPPL
Label · Labeling
Apr 2020 SUPPL
Label · Labeling
Apr 2020 SUPPL
Label · Labeling

What HORIZANT Treats

2 indications

HORIZANT is approved for 2 conditions since its original approval in 2011. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Restless Legs Syndrome
  • Postherpetic Neuralgia
Source: FDA Label

HORIZANT Competitive Set

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Three rings of competition based on shared molecular targets and treated indications.

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Filters applied: drops same-active-ingredient (505(b)(2) reformulations), route-mismatch (topical vs systemic), and cross-therapeutic-area matches in same-indication rings.

Drugs Similar to HORIZANT

3 of 6

FDA-approved drugs for similar conditions. Compare mechanisms and indications to understand treatment alternatives.

GRALISE
GABAPENTIN
1 shared
ALMATICA
Shared indications:
Postherpetic Neuralgia
LYRICA
PREGABALIN
1 shared
CP PHARMS
Shared indications:
Postherpetic Neuralgia
LYRICA CR
PREGABALIN
1 shared
UPJOHN
Shared indications:
Postherpetic Neuralgia
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Clinical Trial Registry

5 trials
Trial Sponsor ID Phase Status Title
NCT03053427 results posted 8825-CL-0101 Ph 4 completed A Study of Oral Dosing of Gabapentin Enacarbil in Japanese Restless Legs Syndrome Patients
NCT01981941 8825-CL-0103 Ph 4 completed Post-marketing Study of Gabapentin Enacarbil to Evaluate the Effect in Restless Leg Syndrome (RLS) Patients With Moderate Renal Impairment
NCT03082755 2016-09-0152 R01AG051588-02 Ph 4 recruiting Nighttime Agitation and Restless Legs Syndrome in People With Alzheimer's Disease
NCT02252536 results posted NCIG - 006 Ph 2 completed HORIZANT (Gabapentin Enacarbil Extended-Release Tablets) for the Treatment of Alcohol Use Disorder
NCT01411124 114111 Ph 1 completed Study to Assess the Effect of Gabapentin Enacarbil on Simulated Driving in Healthy Subjects
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Active Pipeline

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Ongoing clinical trials by development phase

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Key Completed Trials

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Completed studies with published results, ranked by significance

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Trial Timeline

Full development history with FDA approval milestones

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Understanding FDA Approval Types
Count Type What it means
- ORIG Original approval - drug first enters market
- SUPPL - Efficacy New indication (new disease/condition approved)
- SUPPL - Labeling Label text changes (warnings, dosing updates)
- SUPPL - Manufacturing Production changes (new facility)
- SUPPL - Chemistry Formulation changes (new dosage strength)

Green lines in the timeline show ORIG and Efficacy approvals - the clinically meaningful milestones.

HORIZANT FDA Label Details

Indications & Usage

FDA Label (PDF)

HORIZANT is indicated for the treatment of Restless Legs Syndrome; Postherpetic Neuralgia.

View full patent landscape →
3 OB patents · 3 families · 117 international docs across 24 countries

HORIZANT Patents & Exclusivity

Latest Patent: Jun 2029

Patents (3 active)

US8795725 Expires Jun 10, 2029
US8026279 Expires Nov 10, 2026
US8114909 Expires Apr 11, 2026
Source: FDA Orange Book

Pro Intelligence Preview

Deep insights for HORIZANT

Revenue Insights

  • Quarterly revenue tracking
  • Historical trend analysis

Patent Timeline

  • Cliff: 2029
  • 16 active patents

Trial Analysis

  • 5 total trials
  • Stage: Mature

Competitive Landscape

  • 6 similar drugs
  • Same target/indication analysis
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Data Sources

Data sourced from official FDA and NIH databases. Click links to verify on original sources.

How We Calculate These Metrics

Trial Activity Stage

Measures the current development activity pattern based on trial phases, status, and trends. Important: This measures R&D activity, not commercial lifecycle.

Trial statuses: "Active" means recruiting or ongoing. "Completed" means reached planned endpoint. "Terminated" means stopped early—often due to safety, efficacy, or business reasons.

  • Growth: High proportion of early-phase trials (Phase 1/2), active development
  • Expansion: Significant Phase 3 activity, approaching or pursuing approvals
  • Mature: Substantial Phase 4 post-marketing studies
  • Stable: Mixed phase distribution, steady development
  • Declining: Low active trial ratio, reduced R&D investment