TheraRadar
Data updated: May 26, 2026

FIRDAPSE (amifampridine phosphate)

Trial Activity: Declining
Orphan Drug Breakthrough Therapy Priority Review
CNS Approved 2018-11-28

Firdapse is a medication used for patients with Lambert-Eaton myasthenic syndrome (LEMS). It helps both adults and children six years of age and older manage this condition. This therapy is prescribed to address the symptoms associated with this specific syndrome.

Source: FDA Label • CATALYST PHARMS

How FIRDAPSE Works

This medication works by acting as a broad-spectrum potassium channel blocker. Although the exact way it produces its therapeutic effect is not yet fully understood, it exerts its action through this channel-blocking mechanism.

Development Insights

Catalyst Pharmaceuticals, Inc. conducting 6 trials (100%)
7 indications explored (Moderate)
myasthenia gravis, musk (1 trials)
achr myasthenia gravis (1 trials)
myasthenia gravis, generalized (1 trials)
3
Indications
--
Phase 3 Trials
2
Priority Reviews
7
Years on Market

Details

Status
Prescription
First Approved
2018-11-28
Patent Cliff
2037

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Routes
ORAL
Dosage Forms
TABLET

Companies

Active Ingredient: AMIFAMPRIDINE PHOSPHATE

FIRDAPSE Approval History

2019
2020
2021
2022
2023
2024
2025
2026
Original
New Indication
New Form
Label Update
6 FDA actions from 2018 to 2025 · 2 indication expansions
Jul 2025 SUPPL
Mfg · Manufacturing (CMC)
May 2024 SUPPL
Efficacy
May 2023 SUPPL
Label · Labeling

What FIRDAPSE Treats

1 indications

FIRDAPSE is approved for 1 conditions since its original approval in 2018. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Lambert-Eaton Myasthenic Syndrome
Source: FDA Label

FIRDAPSE Competitive Set

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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.

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Clinical Trial Registry

6 trials
Trial Sponsor ID Phase Status Title
NCT03579966 results posted MSK-003 Ph 3 terminated Long Term Safety Study of Amifampridine Phosphate in MuSK-MG (Muscle Specific Tyrosine Kinase Myasthenia Gravis)
NCT03304054 results posted MSK-002 Ph 3 completed Study to Evaluate Amifampridine Phosphate in Patients With MuSK-MG
NCT03781479 results posted SMA-001 Ph 2 completed Controlled Trial to Evaluate Amifampridine Phosphate in Spinal Muscular Atrophy Type 3 Patients
NCT02562066 results posted CMS-001 Ph 3 completed Amifampridine Phosphate for the Treatment of Congenital Myasthenic Syndromes
NCT02970162 results posted LMS-003 Ph 3 completed Phase 3 Study to Evaluate Efficacy of Amifampridine Phosphate in Lambert-Eaton Myasthenic Syndrome (LEMS)
NCT01377922 results posted LMS-002 Ph 3 completed A Phase 3 Study of Amifampridine Phosphate in Patients With Lambert Eaton Myasthenic Syndrome (LEMS)
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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.

FIRDAPSE FDA Label Details

Indications & Usage

FDA Label (PDF)

FIRDAPSE is indicated for the treatment of Lambert-Eaton Myasthenic Syndrome.

View full patent landscape →
6 OB patents · 2 families · 25 international docs across 3 countries

FIRDAPSE Patents & Exclusivity

Latest Patent: Feb 2037

Patents (6 active)

US10626088 Expires Feb 25, 2037
US10793893 Expires May 26, 2034
US11274332 Expires Jun 29, 2032
US11274331 Expires Jun 29, 2032
US11268128 Expires Jun 29, 2032
US11060128 Expires Jun 29, 2032
Source: FDA Orange Book

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Revenue Insights

  • Quarterly revenue tracking
  • Historical trend analysis

Patent Timeline

  • Cliff: 2037
  • 6 active patents

Trial Analysis

  • 6 total trials
  • Stage: Declining

Competitive Landscape

  • Competitor tracking
  • 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