Sabrilex (Vigabatrin)
Antiepileptic medication for treatment-resistant epilepsy and infantile spasms
Sabrilex contains the active substance vigabatrin, an antiepileptic medication that works by increasing the levels of GABA, a natural calming chemical in the brain. It is used as add-on therapy for epilepsy that has not responded adequately to other treatments, and as a first-line treatment for infantile spasms (West syndrome). Due to the risk of irreversible visual field defects, Sabrilex requires careful ophthalmological monitoring throughout treatment and is typically reserved for patients who have not responded to other antiepileptic drugs.
Quick Facts: Sabrilex
Key Takeaways
- Sabrilex (vigabatrin) is an antiepileptic used for treatment-resistant partial epilepsy and infantile spasms (West syndrome)
- Approximately one-third of patients may develop irreversible visual field defects, making regular eye examinations mandatory
- The usual adult maintenance dose is 2-3 g per day (4-6 tablets), always as prescribed by a specialist
- Never stop taking Sabrilex suddenly, as this can trigger seizures - doses must be reduced gradually under medical supervision
- Sabrilex should not be used during pregnancy or breastfeeding unless specifically advised by your doctor
What Is Sabrilex and What Is It Used For?
Quick Answer: Sabrilex (vigabatrin) is an antiepileptic medicine used as add-on therapy for treatment-resistant partial (focal) epilepsy and as monotherapy for infantile spasms (West syndrome). It works by irreversibly inhibiting GABA-aminotransferase, increasing levels of the inhibitory neurotransmitter GABA in the brain.
Sabrilex belongs to a class of medications known as antiepileptic drugs (AEDs). Its active substance, vigabatrin, has a unique mechanism of action among antiepileptics. Rather than acting directly on ion channels or synaptic receptors like many other seizure medications, vigabatrin works by irreversibly inhibiting GABA-aminotransferase (GABA-T), the enzyme responsible for breaking down gamma-aminobutyric acid (GABA). GABA is the principal inhibitory neurotransmitter in the central nervous system, and by preventing its breakdown, vigabatrin increases the concentration of GABA available to inhibit excessive neuronal firing that causes seizures.
The primary indication for Sabrilex is as adjunctive (add-on) therapy for adults and children with treatment-resistant partial epilepsy, also known as focal epilepsy. This means it is used alongside other antiepileptic medications when those drugs alone have not provided adequate seizure control. Sabrilex is typically prescribed by an epilepsy specialist and is usually reserved for patients who have not responded to at least two other appropriate antiepileptic drugs, due to the risk of irreversible visual field defects associated with its use.
Sabrilex also has an important role in the treatment of infantile spasms, also known as West syndrome. Infantile spasms are a specific type of seizure occurring in infants, typically between 3 and 12 months of age, characterized by sudden, brief clusters of muscle spasms. Vigabatrin is considered a first-line treatment for infantile spasms, particularly when they are caused by tuberous sclerosis complex (TSC), where response rates can exceed 90%. For infantile spasms of other etiologies, vigabatrin remains an effective treatment option, though hormonal therapy (such as ACTH or prednisolone) may be preferred in some cases.
The International League Against Epilepsy (ILAE) recognizes vigabatrin as an effective treatment option for both focal seizures and infantile spasms, while emphasizing the importance of weighing the benefits against the risk of visual field loss. Treatment should always be initiated and monitored by a specialist experienced in managing epilepsy.
What Should You Know Before Taking Sabrilex?
Quick Answer: Before starting Sabrilex, inform your doctor about any history of depression or psychiatric disorders, kidney problems, or eye conditions. A baseline eye examination including visual field testing is mandatory before treatment begins. Sabrilex should not be used if you are allergic to vigabatrin.
Contraindications
You must not take Sabrilex if you are allergic (hypersensitive) to vigabatrin or any of the other ingredients in the medication. The inactive ingredients include povidone K30, microcrystalline cellulose, sodium starch glycolate (Type A), magnesium stearate, hypromellose, titanium dioxide, and macrogol 8000. If you have experienced an allergic reaction to any of these substances in the past, inform your doctor immediately.
Warnings and Precautions
Talk to your doctor before taking Sabrilex if any of the following apply to you:
- You have or have previously had depression or any other psychiatric illness
- You have had kidney problems, as dose adjustment may be necessary
- You have had problems with your eyes or vision
- You are pregnant, planning to become pregnant, or breastfeeding
Visual field defects (loss of peripheral vision) can occur during treatment with Sabrilex. Approximately one-third of all patients treated with this medication may develop visual field constriction. These defects can range from mild to severe, and in serious cases may result in tunnel vision and significant vision loss. The visual field loss is generally irreversible (permanent), making early detection essential.
Your doctor should arrange an eye examination including visual field testing and visual acuity assessment before you start Sabrilex, or within 4 weeks of starting treatment, and then every 3 to 6 months throughout treatment. A follow-up eye examination is also recommended 3 to 6 months after stopping treatment, as worsening of visual field defects after discontinuation cannot be ruled out.
Contact your doctor immediately if you notice any changes in your vision.
Sabrilex may also cause reduced vision due to other eye problems such as retinal disorders, blurred vision, optic nerve atrophy, or optic neuritis. If you experience any change in your vision, seek ophthalmological assessment promptly.
A small number of people treated with antiepileptic medications, including vigabatrin, have experienced thoughts of self-harm or suicide. If you experience any such thoughts at any time, contact your doctor immediately. Additionally, symptoms such as drowsiness, reduced consciousness (stupor), or confusion should be reported to your doctor, who may decide to reduce the dose or discontinue treatment.
Use in Children
Movement disorders and abnormalities on brain MRI scans have been reported in young children treated with vigabatrin for infantile spasms (West syndrome). These MRI signal changes are typically seen in the thalamus, basal ganglia, brainstem, and cerebellum, and are usually reversible upon discontinuation of the drug. If you observe an abnormal movement pattern in your child, contact your doctor, who will determine whether a change in treatment is necessary.
Pregnancy and Breastfeeding
If you are pregnant, planning to become pregnant, or breastfeeding, consult your doctor before using Sabrilex. Vigabatrin should not be used during pregnancy unless your doctor specifically advises it, as it may cause harm to the developing fetus. However, you should never stop taking this medication abruptly, as uncontrolled seizures pose significant risks to both maternal and fetal health. Your doctor will help you weigh the risks and benefits and may consider switching to a safer alternative if possible.
Vigabatrin passes into breast milk, and breastfeeding is not recommended during treatment. If you are breastfeeding, discuss this with your doctor before starting Sabrilex so that appropriate arrangements can be made.
Driving and Operating Machinery
Do not drive or operate machinery if your epilepsy is not under control. Sabrilex can sometimes cause drowsiness, dizziness, and impaired concentration and reaction time. If these symptoms occur, avoid any risky activities. Visual field disturbances that may affect driving ability have occurred in patients taking this medication. If you wish to continue driving, your vision must be tested regularly (every six months), even if you have not noticed any changes.
This medicine contains less than 1 mmol (23 mg) sodium per tablet, which means it is essentially sodium-free. This is relevant for patients on a controlled sodium diet.
How Does Sabrilex Interact with Other Drugs?
Quick Answer: The most clinically significant interaction is with clonazepam, which may increase drowsiness when combined with Sabrilex. Vigabatrin can also reduce phenytoin plasma levels by 20-30%. Sabrilex should not be combined with other medications that carry a risk of eye side effects.
Vigabatrin has a relatively limited interaction profile compared to many other antiepileptic drugs, primarily because it is not metabolized by cytochrome P450 enzymes and has minimal protein binding. However, some important interactions do exist that require clinical attention.
Clinically Significant Interactions
| Interacting Drug | Effect | Clinical Significance | Recommendation |
|---|---|---|---|
| Clonazepam | Increased sedation and drowsiness | High | Monitor closely; dose adjustment may be needed |
| Phenytoin | Decreased phenytoin plasma levels (20-30% reduction) | Moderate | Monitor phenytoin levels; adjust dose as needed |
| Carbamazepine | Minor decrease in carbamazepine levels possible | Low | Usually no dose adjustment required |
| Phenobarbital | Minor decrease in phenobarbital levels possible | Low | Monitor if clinically indicated |
| Drugs with ocular toxicity | Additive risk of visual side effects | High | Avoid combination; consult ophthalmologist |
Always inform your doctor or pharmacist about all medications you are currently taking, have recently taken, or might take in the future. This includes prescription and over-the-counter medicines, herbal remedies, and dietary supplements. Sabrilex should not be taken in combination with other medications known to cause eye side effects, as this may increase the risk of visual complications.
Additional Considerations
Unlike many antiepileptic drugs, vigabatrin does not significantly induce or inhibit hepatic cytochrome P450 enzymes. This means it has a lower potential for pharmacokinetic interactions compared to drugs like carbamazepine, phenytoin, or phenobarbital. However, vigabatrin may interfere with certain laboratory tests. It can affect the measurement of amino acids in urine, potentially leading to false-positive results for inborn errors of metabolism. It may also affect the measurement of alanine aminotransferase (ALT) levels, as vigabatrin inhibits transaminases.
What Is the Correct Dosage of Sabrilex?
Quick Answer: The usual starting dose for adults is 1 g (2 tablets) per day, with a maintenance dose of 2-3 g (4-6 tablets) per day. The maximum recommended dose is 3 g per day. Children's doses are calculated based on body weight. Always follow your doctor's instructions exactly.
Always take Sabrilex exactly as your doctor has prescribed. Do not change the dose yourself. Your doctor will prescribe the dose and adjust it individually based on your response to treatment. If you are unsure about anything, consult your doctor or pharmacist.
Adults
Adult Dosing
Starting dose: 1 g (2 tablets) per day
Maintenance dose: 2-3 g (4-6 tablets) per day
Maximum dose: 3 g per day
Your doctor may increase or decrease the dose depending on how you respond to treatment. The daily dose can be taken as a single dose or divided into two doses.
Children
In children with treatment-resistant partial epilepsy, the dose is based on age and body weight. The usual starting dose is 40 mg/kg body weight per day.
| Body Weight | Daily Dose | Tablets Per Day |
|---|---|---|
| 10-15 kg | 0.5-1 g | 1-2 tablets |
| 15-30 kg | 1-1.5 g | 2-3 tablets |
| 30-50 kg | 1.5-3 g | 3-6 tablets |
| Over 50 kg | 2-3 g (adult dose) | 4-6 tablets |
Note that these are guideline doses. Your child's doctor may prescribe a different dose based on individual clinical assessment and response.
The recommended starting dose for children with infantile spasms is 50 mg/kg body weight per day. The dose may be subsequently increased based on clinical response. Treatment for infantile spasms should be initiated and monitored by a pediatric neurologist experienced in managing this condition.
Elderly and Patients with Kidney Problems
If you are elderly or have kidney problems, your doctor may prescribe a lower dose. Since vigabatrin is primarily eliminated through the kidneys as unchanged drug, reduced kidney function can lead to accumulation of the medication. Dose adjustment based on creatinine clearance is recommended in patients with renal impairment to minimize the risk of side effects.
How to Take Sabrilex
Sabrilex tablets are for oral use. Swallow the tablets whole with at least half a glass of water. You can take Sabrilex before or after meals - food does not significantly affect the absorption of the medication. The daily dose can be taken at a single time or divided into two doses.
Missed Dose
If you forget to take a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and take only your next scheduled dose. Do not take a double dose to compensate for a forgotten dose. Maintaining a regular dosing schedule is important for optimal seizure control.
Overdose
If you have taken too much Sabrilex, or if a child has accidentally swallowed the medicine, contact your doctor, hospital emergency department, or poison control center immediately for risk assessment and advice. Symptoms of overdose may include drowsiness, loss of consciousness, or reduced alertness. Treatment of overdose is primarily supportive, and there is no specific antidote for vigabatrin.
Stopping Treatment
Do not stop taking Sabrilex without first discussing with your doctor. If your doctor decides to discontinue treatment, the dose will be reduced gradually over a period of 2 to 4 weeks. Stopping the medication abruptly can cause breakthrough seizures or status epilepticus, which can be life-threatening. Even after the decision to stop treatment is made, gradual dose tapering under medical supervision is essential.
What Are the Side Effects of Sabrilex?
Quick Answer: The most significant side effect is visual field defects (peripheral vision loss), affecting approximately one-third of patients and typically irreversible. Other very common side effects include fatigue, drowsiness, and joint pain. Like some other antiepileptic drugs, vigabatrin may paradoxically increase seizure frequency in some patients.
Like all medicines, Sabrilex can cause side effects, although not everyone experiences them. Some patients treated with antiepileptic medications, including vigabatrin, may experience an increase in seizure frequency. Contact your doctor immediately if this happens.
Very Common
May affect more than 1 in 10 people
- Visual field defects - approximately 1 in 3 patients may develop visual field constriction (loss of peripheral vision). These can range from mild to severe and are usually irreversible. They typically appear after months to years of treatment. Contact your doctor immediately if you notice any visual changes.
- Fatigue and excessive drowsiness (somnolence)
- Joint pain (arthralgia)
Common
May affect up to 1 in 10 people
- Headache
- Weight gain
- Tremor (involuntary shaking)
- Swelling (edema)
- Dizziness
- Tingling or numbness (paraesthesia)
- Concentration and memory difficulties
- Psychological symptoms: anxiety, aggression, nervousness, irritability, depression, thought disturbances, paranoia, insomnia
- Nausea, vomiting, and abdominal pain
- Blurred vision, double vision (diplopia), and nystagmus (rapid involuntary eye movements)
- Speech disturbances
- Anemia (reduced red blood cell count)
- Patchy hair loss (alopecia)
Uncommon
May affect up to 1 in 100 people
- Lack of coordination or clumsiness (ataxia)
- More serious psychiatric disturbances: mania, hypomania, psychosis
- Skin rash
Rare
May affect up to 1 in 1,000 people
- Severe allergic reaction causing swelling of the face or throat (angioedema) - seek immediate medical attention
- Urticaria (hives)
- Reduced consciousness, stiffness, and confusion (encephalopathy) - usually reversible with dose reduction
- Suicide attempt
- Retinal disorders
Very Rare
May affect up to 1 in 10,000 people
- Optic neuritis (inflammation of the optic nerve)
- Optic atrophy (degeneration of the optic nerve)
- Hallucinations
- Liver disorders (hepatitis)
Frequency Not Known
Cannot be estimated from available data
- Reduced visual acuity
- MRI signal abnormalities in the brain
- Myelin edema (swelling of the protective nerve sheath) observed on MRI, particularly in infants
Additional Side Effects in Children
In addition to the side effects listed above, the following have been specifically noted in children:
- Very common: Hyperactivity or restlessness (excitation)
- Frequency not known: Movement disorders in infants treated for infantile spasms; MRI signal abnormalities particularly in infants
Psychiatric symptoms such as anxiety, depression, aggression, nervousness, and paranoia are usually reversible when the dose is reduced or treatment is gradually discontinued. Do not reduce your dose without first consulting your doctor. Contact your doctor if you experience any of these symptoms.
If you experience any side effects, including those not listed above, report them to your doctor or pharmacist. You can also report side effects directly to your national medicines regulatory authority. Reporting side effects helps to continuously monitor the benefit-risk balance of the medication.
How Should You Store Sabrilex?
Quick Answer: Store Sabrilex out of the sight and reach of children. No special storage conditions are required. Do not use after the expiry date printed on the packaging.
Keep this medicine out of the sight and reach of children at all times. Store in a safe location where children and pets cannot access it.
Do not use Sabrilex after the expiry date stated on the outer carton and blister after "EXP." The expiry date refers to the last day of that month. This medicine does not require any special storage conditions - it can be stored at room temperature.
Do not dispose of medications via household waste or through the water supply. Ask your pharmacist about how to properly dispose of medicines that are no longer needed. These measures help protect the environment and prevent accidental exposure.
What Does Sabrilex Contain?
Quick Answer: Each Sabrilex film-coated tablet contains 500 mg of the active substance vigabatrin. The tablets are white to off-white, oval, biconvex, scored on one side and imprinted with "SABRILEX" on the other.
Active Substance
Each film-coated tablet contains 500 mg vigabatrin.
Inactive Ingredients
Tablet core: Povidone K30 (E1201), microcrystalline cellulose (E460), sodium starch glycolate (Type A), magnesium stearate.
Film coating: Hypromellose 15 mPa.s (E464), titanium dioxide (E171), macrogol 8000.
Appearance and Pack Sizes
Sabrilex tablets are white to off-white, oval, biconvex film-coated tablets with a score line on one side and imprinted with "SABRILEX" on the other side. They are available in clear or opaque blisters containing 10 tablets each. Pack sizes: 30, 50, 60, 100, or 200 tablets. Not all pack sizes may be marketed in every country.
International Brand Names
The same medication (vigabatrin) is marketed under different brand names in various countries:
- Sabril: Belgium, France, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, United Kingdom, Germany, Austria
- Sabrilex: Denmark, Finland, Spain, Sweden
The manufacturer is Patheon France S.A., located in Bourgoin-Jallieu, France. The marketing authorization holder varies by country.
Frequently Asked Questions About Sabrilex
Sabrilex (vigabatrin) is an antiepileptic drug used as add-on therapy for treatment-resistant partial (focal) epilepsy when other drug combinations have been inadequate. It is also used as monotherapy for infantile spasms (West syndrome) in infants and young children. Sabrilex works by irreversibly inhibiting GABA-aminotransferase, increasing the levels of the inhibitory neurotransmitter GABA in the brain, which helps control seizures.
Yes, approximately one-third of patients treated with Sabrilex develop visual field defects (peripheral vision loss). These defects can range from mild to severe, and in serious cases may result in tunnel vision. The vision loss is generally irreversible, which is why regular ophthalmological examinations including visual field testing are mandatory before starting treatment, every 3-6 months during treatment, and 3-6 months after stopping treatment. Contact your doctor immediately if you notice any changes in your vision.
Sabrilex tablets should be swallowed whole with at least half a glass of water. They can be taken with or without food. The daily dose can be taken as a single dose or split into two doses. The usual starting dose for adults is 1 g (2 tablets) per day, with a maintenance dose of 2-3 g (4-6 tablets) per day. The maximum recommended dose is 3 g per day. Never change your dose without consulting your doctor, and never stop the medication abruptly.
If you miss a dose, take it as soon as you remember. However, if it is almost time for your next dose, skip the missed dose and take only your next scheduled dose. Do not take a double dose to make up for a forgotten dose. If you frequently forget doses, consider setting a daily reminder to help maintain a consistent schedule. Never stop taking Sabrilex abruptly without medical supervision.
Sabrilex should not be used during pregnancy unless your doctor specifically advises you to do so, as it may cause harm to the developing fetus. If you are pregnant or planning to become pregnant, discuss this with your doctor immediately. Do not stop taking Sabrilex suddenly, as uncontrolled seizures pose risks to both mother and baby. Your doctor will help you weigh the benefits and risks and may consider alternative treatments. Breastfeeding is not recommended during treatment as vigabatrin passes into breast milk.
The most common side effects of Sabrilex (affecting more than 1 in 10 patients) include visual field defects (peripheral vision loss), fatigue and excessive drowsiness, and joint pain. Common side effects (affecting up to 1 in 10 patients) include headache, weight gain, tremor, swelling, dizziness, tingling or numbness, concentration and memory difficulties, psychological symptoms such as anxiety or depression, nausea, blurred vision, and speech disturbances. If you experience any concerning side effects, consult your doctor.
References & Medical Sources
- 1 European Medicines Agency (EMA). Sabril - Summary of Product Characteristics. Last updated 2024. Available from: www.ema.europa.eu
- 2 Willmore LJ, Abelson MB, Ben-Menachem E, et al. Vigabatrin: 2008 Update. Epilepsia. 2009;50(2):163-173. doi:10.1111/j.1528-1167.2008.01988.x
- 3 International League Against Epilepsy (ILAE). Treatment Guidelines for Epilepsy. 2023 Update. Available from: www.ilae.org
- 4 National Institute for Health and Care Excellence (NICE). Epilepsies in children, young people and adults. NICE guideline [NG217]. Updated 2024. Available from: www.nice.org.uk
- 5 Wild JM, Chiron C, Ahn H, et al. Visual field loss in patients with refractory partial epilepsy treated with vigabatrin: final results from an open-label, observational, multicenter study. CNS Drugs. 2009;23(11):965-982.
- 6 Hancock EC, Osborne JP, Edwards SW. Treatment of infantile spasms. Cochrane Database of Systematic Reviews. 2013;(6):CD001770. doi:10.1002/14651858.CD001770.pub3
- 7 World Health Organization (WHO). Model List of Essential Medicines. 23rd List. 2023. Available from: www.who.int
- 8 British National Formulary (BNF). Vigabatrin. 2024. Available from: bnf.nice.org.uk
- 9 US Food and Drug Administration (FDA). Vigabatrin (Sabril) prescribing information and REMS program. Available from: www.fda.gov
- 10 Pellock JM, Hrachovy R, Shinnar S, et al. Infantile spasms: a US consensus report. Epilepsia. 2010;51(10):2175-2189. doi:10.1111/j.1528-1167.2010.02657.x
Editorial Team
This article has been prepared by the iMedic Medical Editorial Team, which includes licensed physicians and pharmacists with expertise in neurology, epileptology, and clinical pharmacology. All medical content is reviewed according to international evidence-based guidelines including those from the EMA, FDA, ILAE, NICE, and WHO.
Content reviewed by board-certified neurologists and clinical pharmacologists following the GRADE evidence framework. All clinical claims are supported by Level 1A evidence from systematic reviews and randomized controlled trials.
iMedic follows strict editorial guidelines: no commercial funding, no pharmaceutical sponsorship, complete independence from industry. All potential conflicts of interest are disclosed. Content is updated regularly to reflect current evidence.