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Data updated: May 26, 2026

CEREBYX (fosphenytoin sodium)

CNS Approved 1996-08-05

CEREBYX is indicated for the treatment of Generalized Tonic-Clonic Status Epilepticus; Seizures.

Source: FDA Label • PARKE DAVIS

How CEREBYX Works

Fosphenytoin is a prodrug that is converted into phenytoin, which provides the medication's anticonvulsant effects. The drug is thought to work by blocking voltage-dependent sodium channels in the membranes of nerve cells. This blockade results in a reduction of sustained, high-frequency neuronal discharges, thereby stabilizing the electrical activity in the brain.

2
Indications
--
Phase 3 Trials
29
Years on Market

Details

Status
Prescription
First Approved
1996-08-05
Routes
INJECTION
Dosage Forms
INJECTABLE

Companies

Active Ingredient: FOSPHENYTOIN SODIUM

CEREBYX Approval History

1997
1998
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2003
2004
2005
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2008
2009
2010
2011
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2013
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2015
2016
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2021
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2026
Original
New Indication
New Form
Label Update
30 FDA actions from 1996 to 2022 · 1 indication expansions
Apr 2022 SUPPL
Label · Labeling
Dec 2021 SUPPL
Label · Labeling
Feb 2021 SUPPL
Label · Labeling

What CEREBYX Treats

2 indications

CEREBYX is approved for 2 conditions since its original approval in 1996. These indications span multiple therapeutic areas including oncology, immunology, and more.

  • Generalized Tonic-Clonic Status Epilepticus
  • Seizures
Source: FDA Label

CEREBYX Boxed Warning

CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION RATES The rate of intravenous CEREBYX administration should not exceed 150 mg phenytoin sodium equivalents (PE) per minute in adults and 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower) in pediatric patients because of the risk of severe hypotension and cardiac arrhythmias. Careful cardiac monitoring is needed during and after administering intravenous CEREBYX. Although the risk of cardiovascular toxicity increases with infusion rates abov...

CEREBYX 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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Active Pipeline

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Key Completed Trials

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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.

CEREBYX FDA Label Details

Indications & Usage

FDA Label (PDF)

CEREBYX is indicated for the treatment of Generalized Tonic-Clonic Status Epilepticus; Seizures.

⚠️ BOXED WARNING

WARNING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION RATES The rate of intravenous CEREBYX administration should not exceed 150 mg phenytoin sodium equivalents (PE) per minute in adults and 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower) in pediatric patients because of the risk of sev...

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Data Sources

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