PHENYTOIN SODIUM

Indications & Dose:

Tonic-clonic seizures

Focal seizures

Prevention and treatment of seizures during or following neurosurgery or severe head injury

• BY MOUTH

Child 1 month–11 years: Initially 1.5–2.5 mg/kg twice daily, then adjusted according to response to 2.5–5 mg/kg twice daily (max. per dose 7.5 mg/ kg twice daily), dose also adjusted according to plasmaphenytoin concentration; maximum 300 mg per day Child 12–17 years: Initially 75–150 mg twice daily, then adjusted according to response to 150–200 mg twice daily (max. per dose 300 mg twice daily), dose also adjusted according to plasma-phenytoin concentration

Adult: Initially 3–4 mg/kg daily, alternatively 150– 300 mg once daily, alternatively 150–300 mg daily in 2 divided doses, alternatively maintenance 200– 500 mg daily, to be taken preferably with or after food, dose to be increased gradually as necessary (with plasma-phenytoin concentration monitoring), exceptionally, higher doses may be used

Status epilepticus

Acute symptomatic seizures associated with head trauma or neurosurgery

• INITIALLY BY SLOW INTRAVENOUS INJECTION, OR BY INTRAVENOUS INFUSION

Child 1 month–11 years: Loading dose 20 mg/kg, then (by slow intravenous injection or by intravenous infusion) 2.5–5 mg/kg twice daily, to be given with blood pressure and ECG monitoring Child 12–17 years: Loading dose 20 mg/kg, then (by intravenous infusion or by slow intravenous injection) up to 100 mg 3–4 times a day, to be given with blood pressure and ECG monitoring Adult: Loading dose 20 mg/kg (max. per dose 2 g), to be given at a rate not exceeding 1 mg/kg/ minute (max. 50 mg per minute), to be given with blood pressure and ECG monitoring, then (by intravenous infusion or by slow intravenous injection or by mouth) maintenance 100 mg every 6–8 hours adjusted according to plasma concentration monitoring, to be given with blood pressure and ECG monitoring 

Contraindications:

Acute porphyrias 

Side Effects:

Cautions:

Enteral feeding (interrupt feeding for 2 hours before and after dose; more frequent monitoring may be necessary) 

Precautions:

Interaction:

Drugs

Chloromphenicol, dicumarol, cimitidine, sulphonamides and isoniazid: These drugs increase the concentration of phenytion in plasma by inhibiting its metabolism.

Carbamezapine : Enhances phenytion metabolism phenytion induces P-450  system which leads to increase in meta-bolism of antiepileptics anticoagulants

Oral contraceptive, doxycycline cyclos-porine, mexiletine, methedone, levodopa: Decreased pharmacological effects of Phenytoin may occur when any of the following drugs are administered concomi-tantly with phenytoin:

Diazoxide, Barbiturates, Carbamazpine, Rifampicin, Chronic ethanol ingestion, Theophylline, Antacids, Charcoal, Sucralfate, Anti-neoplastics, Folic acid, Influenza virus vaccine, Loxapine, Nitrofurantoin, Pyridoxine.

Phenytoin may decrease pharmacological effects of the following drugs: Acetaminophen, Amiodarone, Cardiac glycosides, Corticosteroids, Dicoumarol, Doxycycline, Haloperidol, Oestrogens, Methadone, Mexi-letine, Oral contraceptives, Quinidine, Furosemide, Cyclosporine, Mebendazole, Non depolarising muscle relaxants, Sulfonylureas, Valproic acid.

Corticosteroids: Systemic manifestation of phenytoin induced hypersensitivity reactions masked.

Dopamine: Severe hypotension.

Meperidine: Decreased analgesic effect and increased toxicity with phenytoin.

Primidone: Pharmacological effects of primidone enhanced.

Warfarin: Pharmacological effects enhanced leading to bleeding disorders.

Lab. Tests: May interfere with Metyrapone and 1mg Dexamethasone tests. 

Warnings:

Adverse Effects:

CNS: Usually dose-related: nystagmus, drowsiness, ataxia, dizziness, mental confusion, tremors, insomnia, headache, seizures

CV:bradycardia, hypotension, cardiovascular collapse, ventricular fibrillation, phlebitis.

Eye: photophobia, conjunctivitis, diplopia, blurred vision.

GI: gingival hyperplasia, nausea, vomiting, constipation, epigastric pain, dysphagia, loss of taste, weight loss, weight loss, hepatitis, liver necrosis.

Hematologic: thrombocytopenia, leukopenia, leukocytosis, agranulocytosis, pancytopenia, eosinophilia; megaloblastic, hemolytic, or aplastic anemias.

Metabolic: fever, hyperglycemia, glycosuria, weight gain, edema, transient increased in serum thyrotropic (TSH) level.

Skin: alopecia, hirsutism (especially in young female); rash: scarlatiniform, maculopapular, urticarial, morbilliform; (may be fatal): bullous, exfoliative, or purpuric dermatitis; Stevens-Johnson syndrome, toxic epidermal necrolysis, keratosis, neonatal hemorrhage

Other: acute renal failure, osteomalacia or rickets associated with hypocalcemia and elevated alkaline phosphatase activity, acute pneumonitis, pulmonary fibrosis; periarteritis nodosum, acute systemic lupus erythematosus, carniofacial abnormalities (with enlargement of lips); Peyronieís disease, lymphadenopathy. 

Lactations:

Special Precautions:

Counselling:

Side Effects Or Adverse Reactions:

Patient And Carer Advice: