Information about PHENYTOIN UNIPHARMA
Each Tablet Contains: 100 mg Phenytoin.
Phenytoin sodium tablets are indicated for the following:
• Control of tonic-clonic seizures (grand mal epilepsy), partial seizures (focal including temporal lobe) or a combination of these.
• Prevention and treatment of seizures occurring during or following neurosurgery and/or severe head injury.
Phenytoin sodium has also been employed in the treatment of trigeminal neuralgia but it should only be used as second line therapy if carbamazepine is ineffective or patients are intolerant to carbamazepine.
Note: Phenytoin sodium is not effective in absence status epilepticus or in the prophylaxis and treatment of febrile convulsions.
Posology and method of administration:
Dosage should be individualised as there may be wide interpatient variability in phenytoin serum levels with equivalent dosage. Phenytoin should be introduced in small dosages with gradual increments until control is achieved or until toxic effects appear. In some cases serum level determinations may be necessary for optimal dosage adjustments - the clinically effective level is usually 10-20mg/l (40-80 micromoles/l) although some cases of tonic-clonic seizures may be controlled with lower serum levels of phenytoin. With recommended dosage a period of seven to ten days may be required to achieve steady state serum levels with Phenytoin and changes in dosage should not be carried out at intervals shorter than seven to ten days. Maintenance of treatment should be the lowest dose of anticonvulsant consistent with control of seizures.
Phenytoin sodium tablets contain phenytoin sodium. Although 100 mg of phenytoin sodium is equivalent to 92 mg of phenytoin on a molecular weight basis, these molecular equivalents are not necessarily biologically equivalent. Physicians should therefore exercise care in those situations where it necessary to change the dosage form and serum level monitoring is advised.
Adult Dosage for Seizures:
Initially 3 to 4mg/kg/day with subsequent dosage adjustment if necessary. For most adults a satisfactory maintenance dose will be 200 to 500mg daily in single or divided doses. Exceptionally, a daily dose outside this range may be indicated. Dosage should normally be adjusted according to serum levels where assay facilities exist.
Adult Dosage for Trigeminal Neuralgia:
The clinically effective dose has not been established in clinical trials. In adults, 300-500 mg given in divided daily doses have been reported in the literature. Dosing should be adjusted based on clinical response. Determination of serum phenytoin level is advised. Levels of total phenytoin should not exceed 20 mcg/ml.
Elderly (over 65 years):
Phenytoin clearance is decreased in elderly patients and lower or less frequent dosing may be required (see section 5.2 Pharmacokinetic properties-Age). As with adults the dosage of Phenytoin sodium tablets should be titrated to the patient's individual requirements using the same guidelines. As elderly patients tend to receive multiple drug therapies, the possibility of drug interactions should be borne in mind.
Infants and Children:
Initially, 5mg/kg/day in two divided doses, with subsequent dosage individualised to a maximum of 300mg daily. A recommended daily maintenance dosage is usually 4 mg/kg to 8 mg/kg.
The absorption of phenytoin following oral administration in neonates is unpredictable. Furthermore, the metabolism of phenytoin may be depressed. It is therefore especially important to monitor serum levels in the neonate.
Patients with Renal or Hepatic Disease:
Due to an increased fraction of unbound phenytoin in patients with renal or hepatic disease, or in those with hypoalbuminemia, the interpretation of total phenytoin plasma concentrations should be made with caution. Unbound concentration of phenytoin may be elevated in patients with hyperbilirubinemia. Unbound phenytoin concentrations may be more useful in these patient populations.
Phenytoin is contraindicated in patients who are hypersensitive to phenytoin, or its excipients, or other hydantoins.
Phenytoin crosses the placenta.
There have been also isolated reports of malignancies, including neuroblastoma, in children whose mothers received phenytoin during pregnancy. An increase in seizure frequency during pregnancy occurs in a proportion of patients, and this may be due to altered phenytoin absorption or metabolism. Periodic measurement of serum phenytoin levels is particularly valuable in the management of a pregnant epileptic patient as a guide to an appropriate adjustment of dosage. However, postpartum restoration of the original dosage will probably be indicated.
Breast-feeding is not recommended for women taking phenytoin because phenytoin appears to be secreted in low concentrations in human milk.
Store Below 30° C, Away from Heat and Direct Light and Moisture.
Carton pack contains 40 Tablets.