Formulary
Vigabatrin: Indications, Dosing, Side Effects and Interactions
Vigabatrin clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 5 min read
Vigabatrin: Indications, Dosing, Side Effects and Interactions
Vigabatrin clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Adjunctive treatment of focal seizures with or without secondary generalisation not satisfactorily controlled with other antiepileptics (under expert supervision)**
- **Child** (By Mouth): 12-17 years Initially 250 mg twice daily, to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 1-1.5 g twice daily.
- **Adult** (By Mouth): Initially 1 g once daily, alternatively initially 1 g daily in 2 divided doses, then increased in steps of 500 mg every week, adjusted according to response; usual dose 2-3 g daily; maximum 3 g per day.
- **Child** (By Rectum): 12-17 years Initially 250 mg twice daily, to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 1-1.5 g twice daily.
**Adjunctive treatment of focal seizures with or without secondary generalisation not satisfactorily controlled with other antiepileptics (under expert supervision) for vigabatrin**
- **Neonate** (By mouth): Initially 15-20 mg/kg twice daily, to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 30-40 mg/kg twice daily (max. per dose 75 mg/kg).
- **Child 1-23 months** (By mouth): Initially 15-20 mg/kg twice daily (max. per dose 250 mg), to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 30-40 mg/kg twice daily (max. per dose 75 mg/kg).
- **Child 2-11 years** (By mouth): Initially 15-20 mg/kg twice daily (max. per dose 250 mg), to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 30-40 mg/kg twice daily (max. per dose 1.5 g).
- **Child 12-17 years** (By mouth): Initially 250 mg twice daily, to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 1-1.5 g twice daily.
- **Child 1-23 months** (By rectum): Initially 15-20 mg/kg twice daily (max. per dose 250 mg), to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 30-40 mg/kg twice daily (max. per dose 75 mg/kg).
- **Child 2-11 years** (By rectum): Initially 15-20 mg/kg twice daily (max. per dose 250 mg), to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 30-40 mg/kg twice daily (max. per dose 1.5 g).
- **Child 12-17 years** (By rectum): Initially 250 mg twice daily, to be increased over 2-3 weeks to usual maintenance dose, usual maintenance 1-1.5 g twice daily.
**Infantile spasms [in combination with prednisolone or as monotherapy] (under expert supervision) for vigabatrin**
- **Child 1-23 months** (By mouth): Initially 25 mg/kg twice daily on day 1, followed by 50 mg/kg twice daily on days 2-4; increased if necessary up to 75 mg/kg twice daily from day 5 if spasms continue.
Cautions
Elderly (in adults); history of behavioural problems; history of depression; history of psychosis; seizures (may be exacerbated) Cautions, further information Seizure exacerbation Vigabatrin may exacerbate seizures in patients with absence or myoclonic seizures (including juvenile myoclonic epilepsy), tonic or atonic seizures, Dravet syndrome, Lennox-Gastaut syndrome, and myoclonic-atonic seizures. A Visual field defects Vigabatrin is associated with visual field defects. The onset of symptoms varies from 1 month to several years after starting. In most cases, visual field defects have persisted despite discontinuation, and further deterioration after discontinuation cannot be excluded. Visual field testing should be carried out before treatment and at 6-month intervals. Patients and their carers should be warned to report any new visual symptoms that develop and those with symptoms should be referred for an urgent ophthalmological opinion. Gradual withdrawal of vigabatrin should be considered. M
Contraindications
Visual field defects
Side effects
General side-effects: Rare or very rare Suicidal behaviours Specific side-effects: Common or very common With oral use Abdominal pain; alopecia; anaemia; anxiety; arthralgia; behaviour abnormal; concentration impaired; depression; dizziness; drowsiness; eye disorders; fatigue; headache; insomnia; memory loss; mood altered; nausea; oedema; paraesthesia; speech disorder; thinking abnormal; tremor; vision disorders; vomiting; weight increased Uncommon With oral use Movement disorders; psychotic disorder; seizure (patients with myoclonic seizures at greater risk); skin reactions Rare or very rare With oral use Angioedema; encephalopathy; hallucination; hepatitis; optic neuritis Frequency not known With oral use Intramyelinic oedema (particularly in infants); movement disorder (in infantile spasms) (in children); muscle tone increased Side-effects, further information Encephalopathic symptoms Encephalopathic symptoms including marked sedation, stupor, and confusion with non-specific slow wave EEG can occur rarely -reduce dose or withdraw. Visual field defects About one-third of patients treated with vigabatrin have suffered visual field defects; counselling and careful monitoring for this side-effect are required.
Interactions
**Severe interactions:**
- The plasma concentrations of carbamazepine, phenobarbital, and sodium valproate have also been monitored during controlled clinical trials and no clinically significant interactions have been...
**Other interactions (1):**
- However, during controlled clinical studies, a gradual reduction of 16-33% in the plasma concentration of phenytoin has been observed.
Pregnancy
Important safety information For vigabatrin MHRA/CHM advice: Antiepileptics: risk of suicidal thoughts and behaviour (August 2008) See Epilepsy . MHRA/CHM advice: Antiepileptic drugs: updated advice on switching between different manufacturers' products (November 2017) See Epilepsy . MHRA/CHM advice: Antiepileptic drugs in pregnancy: updated advice following comprehensive safety review (January 2021) See Epilepsy .
Breast feeding
Present in milk-manufacturer advises avoid.
Renal impairment
Dose adjustments Consider reduced dose or increased dose interval if creatinine clearance less than 60 mL/ minute. M See Prescribing in renal impairment .
Medicinal forms
Solution,Tablet,Solution,Solution
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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