Fosphenytoin – Uses, Dosage, Side Effects | Injectable Antiepileptic

Fosphenytoin

Antiepileptic for Status Epilepticus

Indication

Used for status epilepticus, seizure prophylaxis after neurosurgery, and acute seizure control.

Available Form

Injection 75 mg PE/ml (phenytoin equivalent), IV/IM administration only.

Dosage

Adult: 15–20 mg PE/kg IV at a rate ≤150 mg PE/min; may repeat with maintenance dose 4–8 mg PE/kg/day in divided doses.

Pediatric: 15–20 mg PE/kg IV/IM at a rate ≤3 mg PE/kg/min; maintenance 4–8 mg PE/kg/day divided BID/TID.

⚡ Major Side Effects

Hypotension, bradycardia
Arrhythmia, cardiac arrest (rare)
Rash, Stevens-Johnson syndrome (rare)
Local irritation, phlebitis (IV route)

🚫 Contraindications

Hypersensitivity to phenytoin/fosphenytoin
Bradycardia, second- or third-degree AV block
Cardiogenic shock

💧 Compatible Solvent

Fosphenytoin is supplied as ready-to-use IV/IM solution; can be diluted in 0.9% NaCl or Dextrose 5% for slower infusion if needed.

⚠️ Special Precautions

Monitor cardiac function and blood pressure during infusion.
Use caution in patients with cardiac disease.
Infuse at recommended rate to prevent hypotension and arrhythmias.
Adjust maintenance dose in renal/hepatic impairment.