TheraRadar
Data updated: Mar 29, 2026

MYSOLINE

PRIMIDONE
Neurology 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
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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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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

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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

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Indications & Usage

FDA Label (PDF)

MYSOLINE, used alone or concomitantly with other anticonvulsants, is indicated in the control of grand mal, psychomotor, and focal epileptic seizures. It may control grand mal seizures refractory to other anticonvulsant therapy.

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Data Sources

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