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.
To lessen gastric irritation, phenytoin should be taken with or after food.
As with other antiepileptics, withdrawal of phenytoin therapy or transition to or from another type of antiepileptic therapy should be made gradually to avoid precipitating an increase in seizure frequency.
