Phenytoin

DRUG INFORMATION

  ADULT
    - For Status Epilepticus and Non-emergent Loading Dose: Adult loading dose is 10 to
      15 mg/kg at a rate not exceeding 50 mg/min.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - ( 2.2 , 2.3 ) 2.1 General Dosing Information Because of the increased risk of
      adverse cardiovascular reactions associated with rapid administration, intravenous
      administration should not exceed 50 mg per minute in adults.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - Treatment with Phenytoin Sodium Injection can be initiated either with a loading
      dose or an infusion: Loading Dose: A loading dose of parenteral Phenytoin Sodium
      Injection should be injected slowly, not exceeding 50 mg per minute in adults and
      1 to 3 mg/kg/min (or 50 mg per minute, whichever is slower) in pediatric patients.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'dosage and
      administration', retrieved 2026-08-29

  CHILD
    - A loading dose of 15 to 20 mg/kg of Phenytoin Sodium Injection intravenously will
      usually produce serum concentrations of phenytoin within the generally accepted
      serum total concentrations between 10 and 20 mcg/mL (unbound phenytoin
      concentrations of 1 to 2 mcg/mL).
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'pediatric use',
      retrieved 2026-08-29
    - For Status Epilepticus and Non-emergent Loading Dose: Adult loading dose is 10 to
      15 mg/kg at a rate not exceeding 50 mg/min. ( 2.2 ) Pediatric loading dose is 15
      to 20 mg/kg at a rate not exceeding 1 to 3 mg/kg/min or 50 mg/min, whichever is
      slower. ( 2.8 ) Continuous monitoring of the electrocardiogram, blood pressure,
      and respiratory function is essential.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - For Status Epilepticus and Non-emergent Loading Dose: Adult loading dose is 10 to
      15 mg/kg at a rate not exceeding 50 mg/min.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'dosage and
      administration', retrieved 2026-08-29

  RENAL IMPAIRMENT
    - No kidney-impairment dose in this label. Not a statement that none is needed.
      Source: Read and found silent: the US FDA label for phenytoin (Phenytoin Sodium),
      retrieved 2026-08-29

  HEPATIC IMPAIRMENT
    - Because there is approximately an 8% increase in drug content with the free acid
      form over that of the sodium salt, dosage adjustments and serum level monitoring
      may be necessary when switching from a product formulated with the free acid to a
      product formulated with the sodium salt and vice versa.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'dosage and
      administration', retrieved 2026-08-29
    - ( 5.11 , 8.1 ) Renal and/or Hepatic Impairment or Hypoalbuminemia: Monitor unbound
      phenytoin concentrations in these patients.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'use in specific
      populations', retrieved 2026-08-29
    - Lower or less frequent dosing may be required [see Dosage and Administration (2.6)
      ]. 8.6 Renal and/or Hepatic Impairment or Hypoalbuminemia The liver is the site of
      biotransformation.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'use in specific
      populations', retrieved 2026-08-29

  PREGNANCY
    - P regnancy Exposure Registry There is a pregnancy exposure registry that monitors
      pregnancy outcomes in women exposed to antiepileptic drugs (AEDs), such as
      Phenytoin Sodium Injection, during pregnancy.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'pregnancy',
      retrieved 2026-08-29
    - Physicians are advised to recommend that pregnant patients taking phenytoin enroll
      in the North American Antiepileptic Drug (NAAED) Pregnancy Registry.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'pregnancy',
      retrieved 2026-08-29
    - This can be done by calling the toll free number 1-888-233-2334, and must be done
      by patients themselves.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'pregnancy',
      retrieved 2026-08-29

  BREASTFEEDING
    - Malformations (including craniofacial, cardiovascular, neural, limb, and digit
      abnormalities) were observed in rats, rabbits, and mice at doses as low as 100,
      75, and 12.5 mg/kg, respectively. 8.2 Lactation Risk Summary Phenytoin is secreted
      in human milk.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'use in specific
      populations', retrieved 2026-08-29
    - The developmental and health benefits of breastfeeding should be considered along
      with the mother’s clinical need for Phenytoin Sodium Injection and any potential
      adverse effects on the breastfed infant from Phenytoin Sodium Injection or from
      the underlying maternal condition.
      Source: US FDA label for phenytoin (Phenytoin Sodium), section 'use in specific
      populations', retrieved 2026-08-29