TheraRadar
Data updated: Jun 17, 2026

MYSOLINE (primidone)

CNS Approved 1954-03-08

Mysoline (primidone) is an anti-epileptic agent indicated for the control of grand mal, psychomotor, and focal epileptic seizures. It can be administered as a monotherapy or used concomitantly with other anticonvulsant medications. The drug also serves as a therapeutic option for patients with grand mal seizures that have proven refractory to other anticonvulsant treatments.

Source: FDA Label • VALEANT • Anti-epileptic Agent

How MYSOLINE Works

The specific mechanism of primidone’s antiepileptic action is not known, though it has been shown to raise seizure thresholds and alter seizure patterns in animal models. Primidone itself possesses anticonvulsant activity, as do its two metabolites, phenobarbital and phenylethylmalonamide (PEMA). Additionally, the PEMA metabolite serves to potentiate the anticonvulsant activity of phenobarbital.

1
Indication
--
Phase 3 Trials
1
Priority Reviews
72
Years on Market

Details

Status
Prescription
First Approved
1954-03-08
Routes
ORAL
Dosage Forms
TABLET

Companies

Active Ingredient: PRIMIDONE

MYSOLINE Approval History

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Original
New Indication
New Form
Label Update
40 FDA actions from 1954 to 2020
Jun 2020 SUPPL
Mfg · Manufacturing (CMC)
Feb 2016 SUPPL Priority
Mfg · Manufacturing (CMC)
Aug 2011 SUPPL
Update · REMS

What MYSOLINE Treats

4 indications

MYSOLINE is approved for 4 conditions since its original approval in 1954. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Grand Mal Seizures
  • Psychomotor Seizures
  • Focal Seizures
  • Epilepsy
Source: FDA Label

MYSOLINE 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

1 trials
Trial Sponsor ID Phase Status Title
NCT02008123 434350-2 Ph 2 withdrawn Effect of Primidone on Platelet Responsiveness in Patients Determined to be Clopidogrel Resistant
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Active Pipeline

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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.

MYSOLINE FDA Label Details

Indications & Usage

FDA Label (PDF)

MYSOLINE is indicated for the treatment of Grand Mal Seizures; Psychomotor Seizures; Focal Seizures; Epilepsy.

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Data Sources

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