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CEREBYX® Highlights (fosphenytoin sodium)

HIGHLIGHTS OF PRESCRIBING INFORMATION

These highlights do not include all the information needed to use CEREBYX® safely and effectively. See full prescribing information for CEREBYX®.

CEREBYX® (fosphenytoin sodium) injection, for intravenous or intramuscular use
Initial U.S. Approval: 1996

WARNING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION RATES

See full prescribing information for complete boxed warning.

  • 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.
  • Reduction in rate of administration or discontinuation of dosing may be needed (2.3, 2.4, 5.2).

RECENT MAJOR CHANGES

Dosage and Administration (2.3, 2.4) 1/2020
Warnings and Precautions (5.4) 7/2019
Warnings and Precautions (5.7) 7/2019

INDICATIONS AND USAGE

CEREBYX is indicated for the treatment of generalized tonic-clonic status epilepticus and prevention and treatment of seizures occurring during neurosurgery. CEREBYX can also be substituted, as short-term use, for oral phenytoin. CEREBYX should be used only when oral phenytoin administration is not possible. (1)

DOSAGE AND ADMINISTRATION

  • The dose, concentration, and infusion rate of CEREBYX should always be expressed as phenytoin sodium equivalents (PE) (2.1)
  • For Status Epilepticus:
    • Adult loading dose is 15 to 20 mg PE/kg at a rate of 100 to 150 mg PE/min (2.3)
    • Pediatric loading dose is 15 to 20 mg PE/kg at a rate of 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower) (2.3)
  • For Non-emergent Loading and Maintenance Dosing:
    • Adult loading dose is 10 to 20 mg PE/kg given IV or IM; initial maintenance dose is 4 to 6 mg PE/kg/day in divided doses (2.4)
    • Pediatric loading dose is 10 to 15 mg PE/kg at a rate of 1 to 2 mg PE/kg/min (or 150 mg PE/min, whichever is slower); initial maintenance dose is 2 to 4 mg PE/kg every 12 hours at a rate of 1 to 2 mg PE/kg/min (or 100 mg PE/min, whichever is slower) (2.4)
  • Intramuscular Administration:
    • CEREBYX should ordinarily not be given intramuscularly (2.3, 2.4)

DOSAGE FORMS AND STRENGTHS

Injection: 50 mg phenytoin sodium equivalents (PE)/mL available as:

  • 10 mL single-dose injection vials, each containing 500 mg PE (3)
  • 2 mL single-dose injection vials, each containing 100 mg PE (3)

CONTRAINDICATIONS

  • Hypersensitivity to CEREBYX, its ingredients, phenytoin, hydantoins (4)
  • Sinus bradycardia, sino-atrial block, second and third degree A-V block, and Adams-Stokes syndrome (4)
  • A history of prior acute hepatotoxicity attributable to CEREBYX or phenytoin (4, 5.8)
  • Coadministration with delavirdine (4)

WARNINGS AND PRECAUTIONS

  • Dosing Errors: Do not confuse the amount of drug to be given in PE with the concentration of the drug in the vial. Ensure the appropriate volume is withdrawn from the vial when preparing for administration. (5.1)
  • Withdrawal Precipitated Seizure: May precipitate status epilepticus. Dose reductions or discontinuation should be done gradually. (5.3)
  • Serious Dermatologic Reactions: Discontinue at the first sign of a rash, unless clearly not drug-related. If signs or symptoms suggest SJS/TEN, CEREBYX should not be resumed; consider alternative therapy. (5.4)
  • Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/Multiorgan Hypersensitivity: If signs or symptoms of hypersensitivity are present, evaluate the patient immediately. Discontinue if an alternative etiology cannot be established. (5.5)
  • Angioedema: Discontinue immediately if symptoms of angioedema such as facial, perioral, or upper airway swelling occur. (5.7)
  • Hematopoietic Complications: If occurs, follow-up observation is indicated and an alternative antiepileptic treatment should be used. (5.9)

ADVERSE REACTIONS

Most common adverse reactions (incidence ≥10%) are:

  • Adults: pruritus, nystagmus, dizziness, somnolence, and ataxia
  • Pediatrics: vomiting, nystagmus, and ataxia (6.1)

To report SUSPECTED ADVERSE REACTIONS, contact Pfizer, Inc. at 1-800-438-1985 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

DRUG INTERACTIONS

  • Multiple drug interactions because of extensive plasma protein binding, saturable metabolism, and potent induction of hepatic enzymes (7.1, 7.2)

USE IN SPECIFIC POPULATIONS

  • Pregnancy: Phenytoin (the active metabolite of CEREBYX) prenatal exposure may increase risks for congenital malformations and other adverse developmental outcomes (5.15, 8.1)
  • Renal and/or Hepatic Impairment or Hypoalbuminemia: Monitor unbound phenytoin concentrations in these patients (8.6)

See 17 for PATIENT COUNSELING INFORMATION.

Revised: 1/2020

 
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Contact Pfizer Safety to report an adverse event, side effect or concern about the quality of a Pfizer product: (800) 438-1985

You may also contact the U.S. Food and Drug Administration (FDA) directly to report adverse events or product quality concerns at 1-800-FDA-1088 or www.fda.gov/MedWatch