Phenytoin Sodium

Introduction

Phenytoin is an anticonvulsant medication used primarily in the treatment of:

• Tonic-clonic seizures; focal seizures. A period of 5-10 days may be required to achieve anticonvulsant effects.
• Treatment of seizures during or following neurosurgery or severe head injury;
• Status epilepticus;
• Trigeminal neuralgia if carbamazepine inappropriate;
• Abnormal heart rhythm such as ventricular tachycardia and atrial tachycardia.

Pronunciation

Phenytoin sodium 100mg

Phenytoin sodium 30mg

Generic Name 藥名	HA Code 藥物代碼	Classification藥物分類
Phenytoin Sodium Cap 30mg	PHEN31	P1S1S3
Phenytoin Sodium Extended
Release Cap 100mg	PHEN86	P1S1S3

Mechanism of Action

Anticonvulsant medication. It is a sodium channel blocker. It binds to sodium channels and suppresses repetitive neuronal firing.

Dosage

Doses may be expressed in terms of phenytoin or phenytoin sodium; phenytoin 92 mg is equivalent to about 100 mg phenytoin sodium.

As phenytoin has a narrow therapeutic index, need to monitor plasma-phenytoin concentration.

Anticonvulsant effect: 10-20 micrograms/mL (40 to 80 micromoles/litre)

Antiarrhythmic effect: 10-20 micrograms/mL (40 to 80 micromoles/litre)

By mouth, initially 3-4 mg/kg daily or 150 – 300 mg daily (as a single dose or in 2 divided doses) increased gradually as necessary to 600 mg daily. The suggested minimum interval between increments has ranged from about 7 to 10 days. A usual maintenance dose is 200 – 500 mg daily.

For doses in children.