Phenytoin sodium is a commonly used antiepileptic. Phenytoin (fœnit'oin, IPA) acts to suppress the abnormal brain activity seen in seizure by reducing electrical conductance among brain cells by stabilizing the inactive state of voltage-gated sodium channels. Aside from seizures, it is an option in the treatment of trigeminal neuralgia

Trigeminal neuralgia

Trigeminal neuralgia , tic douloureux is a neuropathic disorder characterized by episodes of intense pain in the face, originating from the trigeminal nerve. It has been described as among the most painful conditions known...

 in the event that carbamazepine

Carbamazepine

Carbamazepine is an anticonvulsant and mood-stabilizing drug used primarily in the treatment of epilepsy and bipolar disorder, as well as trigeminal neuralgia...

 or other first-line treatment seems inappropriate.

It is sometimes considered a class 1b antiarrhythmic.
Phenytoin sodium has been marketed as Phenytek by Mylan Laboratories

Mylan Laboratories Inc.

Mylan Inc. is a global generic and specialty pharmaceuticals company headquartered in Canonsburg, Pennsylvania. In 2007, Mylan acquired a controlling interest in India-based Matrix Laboratories Limited, a top producer of active pharmaceutical ingredients for generic drugs, and the generics...

, previously Bertek Pharmaceuticals, and Dilantin; Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

 also Dilantin Kapseals and Dilantin Infatabs in the USA

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

, Eptoin by Abbott Group in India and as Epanutin in the UK

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 and Israel

Israel

The State of Israel is a parliamentary republic located in the Middle East, along the eastern shore of the Mediterranean Sea...

, by Parke-Davis

Parke-Davis

Parke-Davis is a subsidiary of the pharmaceutical company Pfizer. Although no longer an independent corporation, it was once America's oldest and largest drug maker, and played an important role in medical history.- History :...

, now part of Pfizer

Pfizer

Pfizer, Inc. is an American multinational pharmaceutical corporation. The company is based in New York City, New York with its research headquarters in Groton, Connecticut, United States...

.