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How long does vigabatrin (Sabril) take to work?

Medically reviewed by Philip Thornton, DipPharm. Last updated on Oct 17, 2022.

Official answer


Vigabatrin (Sabril) is an antiepileptic or anticonvulsant drug used to treat complex partial seizures and infantile spasms. It is taken twice a day.

After you take a dose of vigabatrin it is completely absorbed by the body and reaches its maximum concentration after about 1 to 2.5 hours, but it may take about one to two weeks to tell if it’s working to stop infantile spasms and quite a few weeks to tell if it’s working to reduce the frequency of your complex partial seizures.

Vigabatrin should be given at the lowest dose and for the shortest period of time possible. Because of this, patients are started on a low dose and the dose is slowly increased depending on response to treatment. For patients with complex partial seizure the dose is increased weekly until the medication works or the maximum dose is reached. For patients with infantile spasms the dose is increased every three days.

During clinical development of vigabatrin for complex partial seizures, it typically took about four to six weeks of slowly increasing the dose of the drug before all of the patients reached their assigned treatment dose. Patients were monitored for between 14 and 18 weeks (which included the time it took to reach their assigned dose) to see if vigabatrin was working for them.

During clinical development of vigabatrin for infantile spasms, it took less time to tell if vigabatrin was working. In one study patients were watched for 5 days to see if vigabatrin was working for them, while in another patients were watched for up to 14 days.


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