FOSPHENYTOIN
(Cerebyx)Standard Prescription
fosphenytoin__mg PE IM/IV x 1 loading dose (__mg PE/kg/dose)
fosphenytoin__mg PE IM/IV Q__H (__mg PE/kg/24h)
fosphenytoin__mg PE IM/IV Q__H (__mg PE/kg/24h)
Dosages
Status Epilepticus:
Loading Dose: 20 mg PE/kg/dose IM/IV (Max: 1500 mg PE/dose). May give additional load of 5-10 mg PE/kg/dose IM/IV after 10 mins if not resolved.
Initial Maintenance for Seizure Disorder:
Infants, Children, and Adolescents:
Loading Dose: 20 mg PE/kg/dose IM/IV (Max: 1500 mg PE/dose). May give additional load of 5-10 mg PE/kg/dose IM/IV after 10 mins if not resolved.
Initial Maintenance for Seizure Disorder:
Infants, Children, and Adolescents:
2.5 mg PE/kg/dose IM/IV Q12H or
1.7 mg PE/kg/dose IM/IV Q8H
(Max: 300 mg PE/24 hr)
(Usual range: 4-10 mg PE/kg/24 hr; Neonates and infants may require Q8H dosing up to 10 mg PE/kg/24 hr)
Mechanism of Action
Anticonvulsant; phosphate ester prodrug for phenytoin; sodium channel blocker
Forms Supplied
Injection: 50 mg PE/mL (=75 mg/mL fosphenytoin sodium)
PE = phenytoin equivalents
Comments
Avoid if allergy to aromatic hydrocarbons (carbamazepine, oxcarbazepine, phenytoin, lamotrigine).
i) No IV/IO access available
ii) IV access is tenuous and extravasation will result in significant morbidity
iii) IV phenytoin not tolerated
PE = phenytoin sodium equivalents
Treatment duration >5 days not evaluated.
At higher serum concentrations, small dose increases can result in disproportionately high serum levels.
IV administration rate up to 3 mg PE/kg/min or 150 mg PE in patients >50 kg.
Adverse effects: Ataxia, nystagmus, somnolence, Steven Johnson Syndrome (rare), hypotension (IV).
Post load (phenytoin) level taken 4 hours after IM load or 2 hours after IV load.
Target serum concentration: 40-80 mcmol/L.
Refer to Therapeutic Drug Monitoring (white pages in hard copy).
References
32, 44, 82, 174, 175
Last Edited
2022-07-02 22:33:32