Vigabatrin


Concise Prescribing Info
Indications/Uses
Adjunct in resistant partial epilepsy.
Dosage/Direction for Use
Adult : PO 1 g/day, increase slowly. Max: 3 g/day.
Dosage Details
Oral
Resistant partial epilepsy with or without secondary generalisation
Adult: As an adjunct: 1 g daily, increase in increments of 0.5 g wkly. Max: 3 g daily in 1-2 divided doses.
Child: As an adjunct: Initially, 40 mg/kg daily, followed by the following maintenance dose: 10-15 kg: 0.5-1 g/day; 15-30 kg: 1-1.5 g/day; 30-50 kg: 1.5-3 g/day; >50 kg: 2-3 g/day. Doses to be admin once or twice daily.
Elderly: Dose reduction may be needed.

Oral
Infantile spasms
Child: As monotherapy: 50 mg/kg daily, adjust according to response over 7 days. Max: 150 mg/kg daily in 1-2 divided doses.
Renal Impairment
<60 ml/min: Dose reduction may be needed; monitor for sedation or confusion.
Administration
May be taken with or without food.
Contraindications
Lactation, preexisting visual field defects, known hypersensitivity.
Special Precautions
History of psychosis, depression or behavioural problems; preexisting clinically significant visual field defect. Visual field function should be assessed at baseline and every 6 mth during treatment. Closely monitor neurological function. Patient to report any new visual symptoms during therapy. Avoid rapid withdrawl, taper over 2-4 wk. May worsen absence seizures. May impair ability to drive or operate machinery. Impaired renal function. Pregnancy, elderly.
Adverse Reactions
Drowsiness, fatigue, dizziness, nervousness, irritability, headache, confusion, depression, aggression, psychosis, excitation and agitation in child, memory disturbance, irreversible visual field defects, diplopia, weight gain, GI disturbances, ataxia, paraesthesia, tremor, inability to concentrate, hepatitis. Decreased LFT, haemoglobin.
Overdosage
Symptoms: Drowsiness, vertigo, headache, psychosis, respiratory depression, apnoea, bradycardia, hypotension, agitation, irritability, confusion, abnormal behaviour, speech disorder and coma. Management: Treatment is supportive.
Drug Interactions
Decreased phenytoin levels with concurrent use. Small decrease in phenobarbital levels with concurrent use.
Lab Interference
May give false positive test for certain rare genetic metabolic disorders as it increases the amount of amino acids in the urine.
Action
Description: Vigabatrin, an analogue of gamma-aminobutyric acid (GABA), is an irreversible inhibitor of GABA-transaminase. It is used in patients with resistant partial epilepsy (with or witho secondary generalisation) as an adjunctive antiepileptic and for unresponsive therapy. It is also used as monotherapy for infantile spasms. No correlation between plasma concentration and efficacy. Duration of drug effect depends on GABA transaminase re-synthesis rate.
Pharmacokinetics:
Absorption: Rapid and completely absorbed from GI tract. Food does not affect absorption.
Distribution: Widely distributed. Not protein bound. Plasma and CSF concentrations increase linearly over recommended dose range.
Metabolism: Not metabolised.
Excretion: Excreted as unchanged drug in urine (70% of dose). No metabolites identified. Terminal half life: 5-8 hr.
MIMS Class
Disclaimer: This information is independently developed by MIMS based on Vigabatrin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
Register or sign in to continue
Asia's one-stop resource for medical news, clinical reference and education
Sign up for free
Already a member? Sign in