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# Vigabatrin

An irreversible inhibitor of the enzyme that breaks down GABA, used for infantile spasms and refractory focal seizures. It can cause permanent vision loss.

Updated 2026-11-01

- Class: [Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/)
- Enzyme: GABA transaminase (GABA-T)
- ATC code: N03AG04

✂**GABA transaminase (GABA-T)**Vigabatrin

ⓘ The figure shows the pig enzyme GABA aminotransferase inactivated by vigabatrin, which stays covalently attached in the active site (ligand VIG); the human enzyme is closely related.

**Target in 3D:** GABA transaminase (GABA-T). PDB structure 1OHW (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/1OHW) · Drag to rotate · pinch to zoom

## Mechanism of action

Vigabatrin is a GABA analogue that irreversibly inhibits GABA transaminase, the enzyme that breaks GABA down. GABA builds up in the brain, strengthening inhibition. Because the enzyme is destroyed, the effect lasts until new enzyme is made.

- Enters the active site of GABA transaminase
- Binds it irreversibly (suicide inhibition)
- GABA is not broken down and builds up
- Stronger inhibition reduces seizures and spasms

## Pharmacokinetics

**Absorption**
Absorbed by mouth; food slows absorption without changing the total amount

**Elimination**
Mainly by the kidneys; the dose is adjusted in kidney disease

## Indications

- Infantile spasms in infants and young children [Epilepsy and seizures →](https://durgical.com/en/conditions/epilepsy-and-seizures/)
- Refractory focal (complex partial) seizures as add-on treatment [Epilepsy and seizures →](https://durgical.com/en/conditions/epilepsy-and-seizures/)

## Adverse effects

### Common

- Sleepiness and fatigue
- Blurred vision
- Dizziness, poor coordination and tremor
- Weight gain
- Headache

### Serious (rare, important)

- Permanent bilateral concentric visual field loss (tunnel vision), sometimes with retinal damage
- MRI signal changes and intramyelinic oedema in some infants
- Anaemia
- Suicidal thoughts

## Contraindications

- None listed in the label; the risk of vision loss limits its use to cases where the benefit is clear

## Key interactions

**Phenytoin**
Lower phenytoin levels

**Other drugs with serious eye effects (retinopathy, glaucoma)**
Avoided together unless the benefit clearly outweighs the risk

## What is monitored

- Vision testing at baseline and regularly during treatment and after it stops
- Early review of benefit: stopped if there is no clear response
- Signs of anaemia
- MRI changes in infants when imaging is done

## Administration and safety

- Given by mouth as tablets or powder for oral solution
- In some countries available only through a restricted programme because of the vision risk
- Withdrawn gradually

## Nursing care

- Explain that vision loss may not be noticed until it is severe, so eye tests are essential
- Check that vision assessments happen on schedule
- In infants, watch alertness and feeding
- Teach to report bumping into objects or clumsiness that may reflect narrowed vision

## Pregnancy and breastfeeding

Human data are limited; it passes into breast milk. Benefits and risks are weighed with specialist care.

## Memory aid

Vigabatrin: «Vision gone by a GABA-T inhibitor» – suicide inhibitor of GABA-T, tunnel vision risk.

## Test yourself

Think of the answer, then tap the question to see it.

## What enzyme does vigabatrin inhibit, and how?

GABA transaminase, irreversibly; GABA is no longer broken down and builds up in the brain.

## What is the boxed warning of vigabatrin?

Permanent bilateral concentric visual field loss (tunnel vision), which may go unnoticed until it is severe.

## In which childhood epilepsy is vigabatrin a key treatment?

Infantile spasms.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/vigabatrin/)

## Related drugs

- [Tiagabine](https://durgical.com/en/pharmacology/tiagabine/)

## Related conditions

- [Epilepsy and seizures](https://durgical.com/en/conditions/epilepsy-and-seizures/)

[← Back to the class: Antiseizure medicines](https://durgical.com/en/pharmacology/classes/antiseizure-medicines/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Vigabatrin: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a610016.html) (MedlinePlus (U.S. National Library of Medicine), 2025); [DailyMed - VIGABATRIN tablet](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=93ba3894-fd97-4432-9f2d-e7050371e91f) (DailyMed (U.S. National Library of Medicine), 2026); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=N03AG04) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/vigabatrin/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/vigabatrin/