Clinical Tools & Calculators

Phenytoin – Loading Dose

For educational use. This tool is intended for reference and education. All care decisions require a direct clinical assessment of the patient and independent verification of doses and values by the treating team. The calculation runs locally in your browser, no patient data is sent to any server.

Phenytoin – Loading Dose

An anticonvulsant used for post-craniotomy seizure prophylaxis or for the control of acute seizures. Fosphenytoin is preferred when it is available, because of its better IV safety profile.

400
mg – loading dose
Max rate 1 mg/kg/min (peds; max 50 mg/min adults)
Clinical notes:
  • Loading: 20 mg/kg IV (max usually 1000–1500 mg).
  • Maintenance: 5–8 mg/kg/day divided q8–12h.
  • Continuous ECG and BP monitoring during loading – risk of arrhythmia and hypotension.
  • Dilute in normal saline only (precipitates in glucose).
  • Check level 2 hr after loading complete (target 10–20 μg/mL total, 1–2 free).
  • Avoid peripheral arterial line / risk of \"purple glove syndrome.\"

Reference: Glauser T, et al. Evidence-based guideline: treatment of convulsive status epilepticus in children and adults. Epilepsy Curr 2016;16(1):48–61. PMID 26900382 · doi:10.5698/1535-7597-16.1.48

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