Fosphenytoin

Generic name: fosphenytoin [ fos-FEN-i-toyn ]
Brand names: Cerebyx, Sesquient
Dosage form: injectable solution (100 mgPE/2 mL; 500 mgPE/10 mL)
Drug class:Hydantoin anticonvulsants

Medically reviewed by Drugs.com on Mar 24, 2022. Written by Cerner Multum.

What is fosphenytoin?

Fosphenytoin is an anticonvulsant that is used to prevent or control seizures. Fosphenytoin is used short term or when other forms of phenytoin cannot be given.

Fosphenytoin may also be used for purposes not listed in this medication guide.

Warnings

Use only as directed. Tell your doctor if you use other medicines or have other medical conditions or allergies.

Before taking this medicine

You should not use fosphenytoin if you are allergic to fosphenytoin or phenytoin, or if you have:

• slow heartbeats;

• Adams-Stokes syndrome (a heart rhythm disorder);

• heart block, AV block;

• liver problems after taking phenytoin (Dilantin); or

• if you also take delavirdine.

Tell your doctor if you have ever had:

• heart disease;

• liver or kidney disease;

• diabetes (fosphenytoin can raise your blood sugar);

• low blood pressure;

• porphyria (a genetic enzyme disorder that causes symptoms affecting the skin or nervous system); or

• if you drink large amounts of alcohol.

Patients of Asian ancestry may have a higher risk of developing a rare but serious skin reaction to fosphenytoin. You may need a blood test to determine your risk of this skin reaction.

Do not start or stop seizure medication during pregnancy without your doctor's advice. Fosphenytoin may harm an unborn baby, but having a seizure during pregnancy could harm both mother and baby. Preventing seizures may outweigh these risks. Tell your doctor right away if you become pregnant.

There may be other seizure medications that are safer to use during pregnancy.

If you receive fosphenytoin during pregnancy, be sure to tell the doctor who delivers your baby. Both you and the baby may need medication to prevent bleeding during delivery and just after birth.

Fosphenytoin can make birth control pills less effective. Ask your doctor about other birth control options such as an injection, implant, skin patch, vaginal ring, condom, diaphragm...