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Status Epilepticus
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Seizure Disorder and unable to take oral medications
- Pregnancy
- Cardiac conduction delays
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Hydantoin anticonvulsant
- Water-soluble phosphate ester prodrug of Phenytoin
- Fosphenytoin is hydrolyzed to Phenytoin by phosphatases
- Increases Neuronal Sodium efflux and stabilizes Neuronal membranes in the motor cortex
- Suppresses the propagation of Seizure activity in the motor cortex
- Dosed in Phenytoin equivalents (PE)
- Transition to oral Phenytoin as soon as possible
- Therapeutic serum level range: 10 to 20 mcg/ml
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Status Epilepticus
- Dose: 15 to 20 PE mg/kg IV or IM (at 3 mg/kg/min up to 100 to 150 mg/min) up to 1000 mg maximum
- Avoid IM dosing if possible
- Non-Emergent Loading Infusion
- Dose: 10 to 15 PE mg/kg IV (at 2 mg/kg/min up to 100 to 150 mg/min) up to 1000 mg maximum
- Maintenance
- Follows loading dose by 12 hours (Status Epilepticus or non-emergent loading)
- For initial dosing only (later dosing should be based on serum levels)
- Start: 2 to 4 PE mg/kg infused slowly (1-2 mg/kg/min up to 100 mg/min) every 12 hours
- Subsequent dosing (based on serum levels)
- Dose 4 to 8 mg PE/kg/day divided every 12 hours based on serum levels
- Preferred over Phenytoin for Status Epilepticus
- Fosphenytoin can be infused with dextrose
- Fosphenytoin has lower risk of Arrhythmia (due to no Ethylene Glycol in base)
- Fosphenytoin may be given IM or delivered a faster IV rate (not tissue toxic)
- However onset of activity is similar to that with Phenytoin (as Fosphenytoin is converted to active Phenytoin form)
- Pregnancy Category X (Known Teratogen)
- See Fetal Hydantoin Syndrome
- Unknown Safety in Lactation
- See Phenytoin
- Severe Hypotension and Cardiac Dysrhythmias
- Infuse slowly
- Cardiac and hemodynamic monitoring during infusion
- (2022) Presc Lett, Resource #361206, Antiseizure Medications
- Olson (2020) Clinical Pharmacology, Medmaster Miami, p. 56-7
- Hamilton (2020) Tarascon Pocket Pharmacopoeia
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