Last reviewed 2026-04-20 · How we verify

PHENYTOIN SODIUM

At a glance

Approved indications

No approved indications tracked.

Boxed warnings

• WARNING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION The rate of intravenous Phenytoin Sodium Injection administration should not exceed 50 mg per minute in adults and 1 to 3 mg/kg/min (or 50 mg per minute, 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 Phenytoin Sodium Injection. Although the risk of cardiovascular toxicity increases with infusion rates above the recommended infusion rate, these events have also been reported at or below the recommended infusion rate. Reduction in rate of administration or discontinuation of dosing may be needed [see Dosage and Administration (2.1) and Warnings and Precautions (5.1) ] . W ARN ING: CARDIOVASCULAR RISK ASSOCIATED WITH RAPID INFUSION S ee full prescribing information for complete boxed warning . The rate of intravenous Phenytoin Sodium Injection administration should not exceed 50 mg per minute in adults and 1 to 3 mg/kg/min (or 50 mg per minute, 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 Phenytoin Sodium Injection. Reduction in rate of administration or discontinuation of dosing may be needed ( 2.1 , 5.1 ).

Common side effects

• Nystagmus
• Ataxia
• Slurred speech
• Decreased coordination
• Mental confusion
• Dizziness
• Insomnia
• Transient nervousness
• Motor twitchings
• Headaches
• Nausea
• Vomiting

Key clinical trials

• A Study to Evaluate VH4524184 Tablet Absorption, Effects of Food, and Interactions With Other Drugs in Healthy Adults (PHASE1)
• A Study of the Effect of Itraconazole and Phenytoin on Calderasib (MK-1084) in Healthy Adults (MK-1084-008) (PHASE1)
• Levetiracetam Versus Phenobarbitone for the Treatment of Neonatal Seizures in a Tertiary Care Hospital. (NA)
• Effect of Phenytoin or Itraconazole on How BGB-16673 is Absorbed and Removed From the Body in Healthy Participants (PHASE1)
• Population Pharmacokinetics of Antiepileptic in Pediatrics
• Antiseizure Medication in Seizure Networks at Early Acute Brain Injury (PHASE4)
• Drug-Drug Interaction Study of Casdatifan in Healthy Adult Participants (ARC-29) (PHASE1)
• Early Post-Traumatic Seizures Prevention Trial (E-PTS Trial) (PHASE4)

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• PHENYTOIN SODIUM CI brief — competitive landscape report
• PHENYTOIN SODIUM updates RSS · CI watch RSS