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Vigabatrin: what it treats, how it is given, and which form to use

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Vigabatrin is a prescription antiseizure medicine used mainly for infantile spasms, especially when they are caused by tuberous sclerosis complex (TSC), and as an add-on for refractory complex partial seizures.1 It works by blocking the enzyme that breaks down GABA, the brain's main calming chemical.2 Its most important risk is permanent loss of side vision, which is why it is only available through an FDA safety program.3

This site lays out what the evidence says about vigabatrin. It pays particular attention to a practical question parents face every day: how the medicine is prepared and measured, and how the ready-to-use liquid compares with powder sachets and tablets.

What vigabatrin treats

The FDA approved vigabatrin (Sabril tablets and powder) in August 2009.4 It is labeled for two uses:1

  • Infantile spasms, on its own, in babies 1 month to 2 years old when the benefits outweigh the risk of vision loss.
  • Refractory complex partial seizures, as an add-on in people 2 years and older who have not responded well to several other treatments. It is not meant to be a first medicine for these seizures.

Vigabatrin works especially well when spasms are caused by tuberous sclerosis complex. In one review, spasms stopped completely in 95% of babies with TSC compared with 54% of babies with other causes.5 Guidelines around the world name it the first choice for TSC-related spasms.6 For spasms with other causes, hormone treatment (ACTH or prednisolone) usually works better as a first treatment.7 See infantile spasms and tuberous sclerosis for the details.

The three forms of vigabatrin

Vigabatrin comes as a ready-to-use liquid, as powder in 500 mg packets that is mixed with water, and as 500 mg tablets. The medicine inside is the same; what differs is the work needed before each dose, the volume given, and who each form is labeled for.3

Ready-to-use liquid

Before each dose
Draw up the dose. No mixing.3
Strength
100 mg per mL
One maximum dose for a 10 kg infant
7.5 mL
After opening
Bottle keeps 90 days at 2–30 °C
FDA-labeled for
Infantile spasms, 1 month to 2 years
Handling (NIOSH)
No packets to open or tablets to crush.9

Powder sachets

Before each dose
Empty 1–3 packets into a cup, dissolve each in 10 mL of water, then draw up the dose.1
Strength
50 mg per mL once mixed (500 mg packet in 10 mL)
One maximum dose for a 10 kg infant
15 mL, mixed from 2 packets; 5 mL thrown away
After opening
Mix fresh for every dose and discard what is left
FDA-labeled for
Infantile spasms (1 month–2 years) and refractory complex partial seizures (2 years and up)
Handling (NIOSH)
Powder is poured out and dissolved at every dose

Tablets

Before each dose
Swallow the tablet.8
Strength
500 mg tablet, scored
One maximum dose for a 10 kg infant
Not used for infants
After opening
Store in the bottle
FDA-labeled for
Refractory complex partial seizures, 2 years and up (infants are dosed with oral solution)
Handling (NIOSH)
Crushing or splitting raises exposure9

The difference is easiest to see in one dose. For a 10 kg baby at the highest labeled dose, the ready-to-use liquid is 7.5 mL drawn straight from the bottle. The same dose from powder is 15 mL, mixed from two packets in 20 mL of water, with the rest thrown away.1

One dose for a 10 kg baby at the maximum labeled dose (750 mg)

Ready-to-use liquid, 100 mg/mL

7.5 mL

Drawn straight from the bottle. Fits in one 10 mL oral syringe.

Mixed powder, 50 mg/mL

15 mL

Two packets dissolved in 20 mL of water; 15 mL is given and 5 mL is thrown away. More than one 10 mL syringe-full.

Scale marks every 1 mL, 0–20 mL. Volumes from the FDA dosing tables for each product. Twice daily.

In the only study that compared the two directly, every dose measured from the ready-to-use liquid landed within 5% of the target, while 7 of 30 doses made from powder missed by more than 10%. That study was small and funded by the liquid's maker; the full comparison explains what it does and does not show.10

How it is dosed

For infantile spasms, the label starts at 50 mg per kg of body weight per day, split into two doses, and can go up every 3 days to a maximum of 150 mg/kg/day.3 For refractory complex partial seizures in adults, it starts at 500 mg twice a day and is usually increased to 1,500 mg twice a day.8 Children 2 to 16 years old are dosed by weight. The dosage page has the full tables and a calculator.

Safety: vision, the REMS, and other effects

Vigabatrin can cause permanent narrowing of the visual field. In a review of 32 studies, field loss was found in 52% of adults and 34% of children who took it.11 Because of this, prescribers, pharmacies and patients must all be enrolled in the Vigabatrin REMS, and vision is checked soon after starting, during treatment and after stopping.3

In babies, vigabatrin can also cause changes on brain MRI scans, usually temporary (22% of infants on vigabatrin compared with 4% of infants on other treatments in one analysis).12 Sleepiness and irritability are the most common other side effects in babies.13 See side effects and vision loss.

Brands and generics

Vigabatrin is sold in the US as Sabril (tablets and powder), Vigafyde (ready-to-use liquid), Vigadrone and Vigpoder (powder), and as generic powders and tablets from several makers.14 Vigafyde is the only ready-to-use liquid.15 See brands and generics.

Where to go next

Common questions

What is vigabatrin used for?

Vigabatrin is FDA-approved on its own for infantile spasms in babies 1 month to 2 years old, and as an add-on medicine for refractory complex partial (focal) seizures in people 2 years and older whose seizures have not responded to several other medicines.

Is there a liquid form of vigabatrin?

Yes. Vigafyde is a ready-to-use vigabatrin oral solution (100 mg/mL), FDA-approved in June 2024 for infantile spasms in babies 1 month to 2 years old. It needs no mixing. Other vigabatrin products for babies are powders that are mixed with water before each dose.

What is the boxed warning for vigabatrin?

Vigabatrin can cause permanent loss of peripheral vision. The risk rises with dose and time on treatment, and no dose is known to be risk-free. Vision must be checked no later than 4 weeks after starting, at least every 3 months during treatment, and 3 to 6 months after stopping.

What drug class is vigabatrin?

Vigabatrin is an antiseizure medicine that irreversibly blocks GABA transaminase, the enzyme that breaks down the calming brain chemical GABA. Blocking it raises GABA levels in the brain.

References

  1. 1.SABRIL (vigabatrin) for oral solution prescribing information, revised 10/2021. Source
  2. 2.Gidal BE, Privitera MD, Sheth RD, et al. Vigabatrin: a novel therapy for seizure disorders. Ann Pharmacother. 1999;33(12):1277-1286. PMID 10630829 · DOI 10.1345/aph.18376 PubMed · DOI
  3. 3.VIGAFYDE (vigabatrin) oral solution prescribing information, revised 11/2025. Source
  4. 4.Drugs@FDA: NDA 020427 SABRIL tablet 500 mg and NDA 022006 SABRIL for oral solution 500 mg/packet, Lundbeck. Both approved 2009-08-21. Source
  5. 5.Hancock E, Osborne JP. Vigabatrin in the treatment of infantile spasms in tuberous sclerosis: literature review. J Child Neurol. 1999;14(2):71-74. PMID 10073425 · DOI 10.1177/088307389901400201 PubMed · DOI
  6. 6.Erdemir G, Rao CK, Pino AF, et al. Diagnosis and management guidelines for infantile epileptic spasms syndrome around the world: A scoping review and comparative study of international approaches. Epilepsia. 2026;67(9):4600-4617. PMID 42274306 · DOI 10.1002/epi.70329 PubMed · DOI
  7. 7.Xu Z, Gong P, Jiao X, et al. Efficacy of vigabatrin in the treatment of infantile epileptic spasms syndrome: A systematic review and meta-analysis. Epilepsia Open. 2023;8(2):268-277. PMID 36740237 · DOI 10.1002/epi4.12703 PubMed · DOI
  8. 8.SABRIL (vigabatrin) tablets prescribing information, revised 10/2021. Source
  9. 9.NIOSH. Managing Hazardous Drug Exposures: Information for Healthcare Settings. Hodson L, Ovesen J, Couch J, et al. DHHS (NIOSH) Publication No. 2023-130, April 2023. DOI 10.26616/NIOSHPUB2023130 DOI
  10. 10.Gibson R, Klima R, Van Horn J. Liquid Medication Dosing Errors: Comparison of a Ready-to-Use Vigabatrin Solution to Reconstituted Solutions of Vigabatrin Powder for Oral Solution. Adv Ther. 2025;42(3):1484-1493. PMID 39899223 · DOI 10.1007/s12325-024-03089-0 · PMC11868180 (Epub Feb 2025; often cited as 2024) PubMed · DOI
  11. 11.Maguire MJ, Hemming K, Wild JM, et al. Prevalence of visual field loss following exposure to vigabatrin therapy: a systematic review. Epilepsia. 2010;51(12):2423-2431. PMID 21070215 · DOI 10.1111/j.1528-1167.2010.02772.x PubMed · DOI
  12. 12.Wheless JW, Carmant L, Bebin M, et al. Magnetic resonance imaging abnormalities associated with vigabatrin in patients with epilepsy. Epilepsia. 2009;50(2):195-205. PMID 19054414 · DOI 10.1111/j.1528-1167.2008.01896.x PubMed · DOI
  13. 13.Walker SD, Kälviäinen R. Non-vision adverse events with vigabatrin therapy. Acta Neurol Scand Suppl. 2011;(192):72-82. PMID 22061182 · DOI 10.1111/j.1600-0404.2011.01602.x PubMed · DOI
  14. 14.Drugs@FDA (openFDA): numerous ANDAs for vigabatrin for oral solution 500 mg/packet and tablets 500 mg. Examples: VIGADRONE ANDA 210196 (approved 2018-06-21; DailyMed labeler now Upsher-Smith); VIGPODER ANDA 214961 (Pyros); Teva, Amneal, Dr. Reddy's, Zydus and others. VIGAFYDE was the only vigabatrin "SOLUTION" (ready-to-use) dosage form in the results. Source
  15. 15.Drugs@FDA (openFDA API): NDA 217684, VIGAFYDE (vigabatrin) oral solution 100 mg/mL, sponsor Pyros Pharms; original approval 2024-06-17. Source

All sources used on this site, with summaries