Vigabatrin research in plain language

Short answer: the most important vigabatrin studies show that it works well for infantile spasms caused by tuberous sclerosis, less well than hormones for most other infantile spasms, and that it carries a real risk of vision loss. Preventive use in tuberous sclerosis is still debated, because the two trials of it disagree.^1,2,3,4

Each summary below covers what the study asked, who was in it, what it found, and its limits. For how these results shape treatment, see infantile spasms, tuberous sclerosis and vision loss. The full reference list is on sources.

Ready-to-use liquid vs powder study (2025)

What it asked. Can caregivers measure a dose more accurately from the ready-to-use liquid than from powder they mix themselves?⁵

Who. 30 lay users: 15 caregivers who had given vigabatrin powder before and 15 people who had never used an oral syringe. Each prepared one 1,125 mg dose of each product, using only written instructions.⁵

What it found.

• All 30 ready-to-use doses were within 5% of the target. Only 23 of 30 powder doses (77%) were within 10%.
• Powder doses ranged from 425 mg to 1,390 mg, from 62% too low to 24% too high.
• On average, the liquid delivered 99% of the target dose and the powder 90%.
• People measured volumes equally well with both. The errors came from mixing the powder.
• Experienced caregivers were no better with powder (10 of 15 within 10%) than first-time users (13 of 15).⁵

Limits. The authors were employees of the company that makes the ready-to-use liquid. The study was small, each person made a single dose in a test setting, and the liquid used was a stand-in solution whose dose was calculated from volume rather than measured in the lab. People could not ask questions, which the authors note is not how the label expects caregivers to be taught. The 1,125 mg target was larger than a typical infant dose. No study has compared seizure outcomes between the two forms.⁵

Read the paper: Comparison of a ready-to-use vigabatrin solution to reconstituted solutions of vigabatrin powder (open-access PDF, CC BY-NC). More context is on liquid vs powder.

Powder stability study (2025)

What it asked. Does vigabatrin powder stay stable after mixing in water, juice, milk or infant formula?⁶

What it found. Powder (Vigadrone) mixed in water, apple juice, whole milk or infant formula and kept in the fridge in capped glass met quality standards for strength and impurities at 0, 24 and 48 hours.⁶

Limits. This was a lab study, not a study of families, and its authors came from the company that makes the powder. The approved labels have not changed: they still say to mix each dose in water, use it right away and throw away the rest.^6,7

PREVeNT trial (2023)

What it asked. If infants with tuberous sclerosis complex (TSC) start vigabatrin early, before seizures, does it improve development and prevent epilepsy?⁴

Who. 56 infants with TSC, randomly assigned to vigabatrin (29) or placebo (27).⁴

What it found.

• Cognitive scores at 24 months were similar in both groups.
• There was no difference in how many children developed epilepsy or drug-resistant epilepsy.
• Infantile spasms were less common, and started later, with vigabatrin.⁴

Limits. The trial was small. Its main question, development, came out negative, and it did not show fewer focal seizures. Its results differ from EPISTOP's, below.⁴

Read the paper: Early treatment with vigabatrin does not decrease focal seizures or improve cognition in tuberous sclerosis complex (open-access PDF, CC BY-NC).

EPISTOP trial (2021)

What it asked. In infants with TSC, does preventive vigabatrin, given before seizures, work better than conventional treatment started after seizures?³

Who. 94 infants with TSC, in a randomized part and an open-label part.³

What it found.

• The first seizure came later with preventive treatment: after 364 vs 124 days in the randomized part, and 426 vs 106 days in the open-label part.
• At 24 months, preventive treatment lowered the risk of clinical seizures (odds ratio 0.21) and drug-resistant epilepsy (odds ratio 0.23).
• No infant on preventive treatment developed infantile spasms (p under 0.001).³

Limits. The trial was small, and part of it was open-label, meaning families and doctors knew which treatment was given. A later trial, PREVeNT, did not find benefits for development or epilepsy overall.^3,4

Read the paper: Prevention of epilepsy in infants with tuberous sclerosis complex in the EPISTOP trial (open-access PDF, CC BY-NC).

ICISS trial (2017 and 2018)

What it asked. For infantile spasms, does adding vigabatrin to hormonal treatment work better than hormonal treatment alone?⁸

Who. 377 babies with infantile spasms. Vigabatrin was given at 100 mg/kg/day or more.⁸

What it found.

• Spasms stopped between days 14 and 42 in 72% on the combination and 57% on hormones alone.⁸
• At 18 months, development scores were the same (73.9 vs 72.7), and so were epilepsy rates (30.0% vs 29.2%).
• Across both groups, babies whose spasms stopped early had higher development scores (79.1 vs 63.2), and a longer delay to treatment was linked to lower scores.⁹

Limits. The trial was open-label. The faster early response with the combination did not lead to better development at 18 months.^8,9

UKISS trial (2004, 2005 and 2010)

What it asked. For infantile spasms not caused by TSC, does hormonal treatment (prednisolone or tetracosactide) work better than vigabatrin?¹⁰

Who. 107 babies; babies with TSC were excluded.¹⁰

What it found.

• At days 13 to 14, spasms had stopped in 73% on hormones and 54% on vigabatrin. Side effects were similar.¹⁰
• By 12 to 14 months, spasm-free rates were the same (75% vs 76%). Overall development scores were similar, but babies with no known cause for their spasms scored higher after hormonal treatment (88.2 vs 78.9).¹¹
• At 4 years, 77 children were traced. Overall scores were not significantly different, but children with no known cause again scored higher after hormones (96 vs 63).¹²
• A further analysis found that each step up in the delay before treatment was linked to a 3.9-point lower development score at 4 years.¹³

Limits. The trial was modest in size, and only part of the original group could be traced at 4 years.¹²

Time to remission study (2022)

What it asked. How quickly do babies with new infantile spasms respond to treatment, and does a fast response predict a lasting one?¹⁴

Who. 395 babies with new-onset infantile spasms.¹⁴

What it found. 43% went into remission within 2 weeks, and 81% of those did so within the first week. The median time to response was 3 days for vigabatrin, 4 days for ACTH and 3 days for steroids. The authors advise reassessing straight away any baby who has not responded after 1 week.¹⁴

Limits. This was an observational study, not a randomized trial, so it shows patterns rather than proving cause.

Vision loss review (2010)

What it asked. How common is visual field loss after vigabatrin?²

Who. 32 studies, with 1,678 people exposed to vigabatrin and 406 controls.²

What it found. Visual field loss was found in 44% of exposed people and 7% of controls. Pooled rates were 52% in adults and 34% in children. Exposed people were about 4 times as likely to have field loss, and risk rose with total dose and with age.²

Limits. The studies differed in design. Research on children treated as infants has found a range of results: in one small study only 1 of 16 had mild field loss at school age, while a larger international study found defects in 11 of 32.^15,16 See vision loss.

Brain MRI studies (2017 and 2025)

Some babies on vigabatrin show changes on brain MRI scans. In the data behind the label, they were seen in 22% of babies on vigabatrin vs 4% on other treatments.^17,18 In several studies the changes went away after vigabatrin was stopped or over time.^19,20 Two studies disagree about what raises the risk.

Hussain 2017. Changes without symptoms were linked to the peak daily dose, not the total dose. Changes with symptoms were seen in 4 of 104 babies and may have been linked to taking hormones at the same time. The authors advise caution above 175 mg/kg/day.²¹

Sathe 2025. Changes were seen in 17 of 108 babies, 11 with symptoms. Changes with symptoms were linked to taking hormones at the same time, and not to peak dose.²²

What this means. Both studies point to combined vigabatrin and hormonal treatment as a possible risk for symptomatic changes. They disagree about whether the dose matters. Both were small and observational. See side effects.