Vigabatrin
Anti-epileptic · GABA analogue
Indications
Adjunct in partial seizures with or without secondary generalization inadequately controlled or intolerant to all other anticonvulsant combination. Monotherapy for infantile spasm.
Dosage
Adults: Initially 1 gm daily in single or two divided doses adding to existing therapy. Adjust dose in 500 mg weekly increments according to response; max 3 gm daily. Discontinue if control of epilepsy is not significantly improved. Children: Adjunctive treatment of focal seizures with or without secondary generalisation not satisfactorily controlled with other antiepileptics: Neonate, initially 15-20 mg/kg twice daily increased over 2-3 wk to usual maintenance dose 30-40 mg/kg twice daily, max 75 mg/kg twice daily; 1 mth-2 yr, initially 15-20 mg/kg twice daily increased over 2-3 wk to usual maintenance dose 30-40 mg/kg twice daily, max 75 mg/kg twice daily; 2-12 yr, initially 15-20 mg/kg (max 250 mg) twice daily increased over 2-3 wk to usual maintenance dose 30-40 mg/kg (max 1.5 gm) twice daily; 12-18 yr, initially 250 mg twice daily increased over 2-3 wk to usual maintenance dose…
Adverse Effects
Irreversible visual field defects, somnolence, agitation, aggression, nervousness, depression, paranoid reactions, fatigue, headache, weight gain, tremor, oedema, dizziness, paraesthesia, GI upset, blurred vision, diplopia, nystagmus, arthralgia, anaemia, attention, memory and thought disturbances, alopecia, oedema, irritability . Excitation and agitation in children. Reports of movement disorders. Encephalopathic symptoms.
Risk Factor (Pregnancy/Lactation)
Pregnancy: Risk cannot be ruled out. Lactation: Contraindicated or not recommended. Contraindications: Pre-existing visual field defect. Precautions: History of psychosis, depression or behavioural problems. Monitor patients for suicidal thoughts and behavior; advise patients to seek medical attention if mood changes or suicidal thoughts develops. Renal impairment. Monitor neurological functions. Test visual field before treatment initiation and every 6 months; advise patients to report new visual problems, if develops refer to ophthalmologist and consider discontinuation. Withdraw gradually. Elderly.
Interactions
Phenytoin, ALT and AST liver test, St. John's Wort, clonazepam, other retinotoxic drugs.
Advice to Patient
Take with or without meals. There is a risk of permanent vision loss with this medication. Do not stop taking medication abruptly, gradually lower the dose and then stop. On start of therapy or change of dosage, patient must be watched for suicidal tendency.
Pharmacokinetics
Absorption: Well absorbed. Metabolism: Almost no metabolic transformation. Half-life elimination: Terminal: Infants (5 mths-2 yrs): 5.7 hrs. Children (10 yrs-16 yrs): 9.5 hrs. Adults: 10.5 hrs. Time to peak, plasma: 1-2 hrs. Excretion: Urine (60%-80%).
Brands with this active ingredient
Compiled by Healify Pharmacy from published drug references. How we compile it →
Always consult a pharmacist or doctor.