Tablet
- Strengths
- 500 mg
- Product note
- Refractory focal seizure product; not the infant dosing presentation.
Vigabatrin
Sabril · Vigafyde
Seizure aggravation / coverage
May aggravate absence or myoclonic seizures; review syndrome before use (NICE NG217, UK guidance).
May aggravate absence or myoclonic seizures; review syndrome before use (NICE NG217, UK guidance).
DailyMed-verified antiseizure indications
Indication / use
- Label / evidence summary
- Vigabatrin / Sabril: adjunctive treatment of refractory complex partial seizures from age 2 years after inadequate response to several alternatives; not first-line therapy. Sabril powder and Vigafyde solution: monotherapy for infantile spasms from age 1 month through 2 years when benefit outweighs vision-loss risk.
- Role
- Maintenance
- Class
- Irreversible GABA transaminase inhibition
Indications checked 26 September 2026. Product, route, age, and treatment-role limits apply. A DailyMed listing alone does not establish FDA approval.
- Representative source · Vigabatrin powder for oral solution — DailyMed label (PDF) ↗
- Representative source · Vigabatrin tablet — DailyMed label (PDF) ↗
- Vigafyde ready-to-use solution — DailyMed label (PDF) ↗
- Vigabatrin powder for oral solution U.S. label
Infantile epileptic spasms syndrome (IESS) · 1 month and older (through 2 years) · MaintenanceMonotherapy when benefits outweigh vision risk.
- Vigabatrin tablet U.S. label
Focal seizures · 2 years and older · MaintenanceRefractory adjunctive therapy; not first line.
- Vigafyde ready-to-use solution U.S. label
Infantile epileptic spasms syndrome (IESS) · 1 month and older (through 2 years) · Maintenance100 mg/mL, twice the concentration of reconstituted powder. REMS and vision monitoring apply.
Formulations & strengths
U.S. products unless another country is named. Strengths are per unit or stated volume.
Powder for oral solution
- Strengths
- 500 mg packet → 50 mg/mL after mixing each packet with 10 mL water
- Product note
- Prepare immediately before dosing; discard unused portion. Different concentration from Vigafyde.
Ready-to-use oral solution (Vigafyde)
- Strengths
- 100 mg/mL
- Product note
- Twice the concentration of the reconstituted 50 mg/mL powder. Labeled for infantile spasms ages 1 month–2 years.
Brand & formulation labels
Each link names the product and formulation it covers. Archived labels do not establish current availability.
Dosing & administration
- Adult / product-specific schedule
- 500 mg twice daily; increase weekly to 1,500 mg twice daily.
- Pediatric
- Infantile spasms: 50 mg/kg/day, titrate by 25–50 mg/kg/day to max 150 mg/kg/day.
- Titration / repeat dosing
- Adults: 500 mg twice daily; increase total dose by 500 mg/day weekly to 1,500 mg twice daily. Infantile spasms: 50 mg/kg/day in 2 doses; increase by 25–50 mg/kg/day every 3 days to 150 mg/kg/day.
Dose adjustment & concentrations
- Renal impairment
- Reduce dose by renal function.
- Hepatic impairment
- No adjustment expected.
- Serum reference information
- No established therapeutic range
Safety
- Boxed warning
- Boxed warning—permanent vision loss. Concentric field loss has been reported in ≥30% of adults when systematically assessed; infant risk cannot be reliably estimated. Risk increases with cumulative dose and duration.
- Contraindications
- None listed in the linked label; permanent vision-loss warning still applies.
- Serious precautions & monitoring
- Permanent vision loss: assess at baseline (no later than 4 weeks after starting), at least every 3 months, and 3–6 months after stopping. Withdraw for inadequate benefit within 3 months in refractory focal seizures or 2–4 weeks in infantile spasms; taper under specialist supervision. REMS requirements apply.
Common / selected adverse effects
- Somnolence
- Fatigue
- Dizziness
- Nystagmus
- Tremor
- Weight gain
Drug interactions: toxicity & clinical action
| Partner / combination | Clinical effect | Clinical action |
|---|---|---|
| Phenytoin | Can lower phenytoin concentration. | Monitor seizure control/levels and adjust only when clinically needed. |
| Clonazepam / sedating drugs | Increased clonazepam exposure and/or additive sedation can occur. | Monitor alertness and tolerability. |
| Laboratory assays | May lower measured ALT/AST activity and interfere with selected metabolic/amino-acid tests. | Inform the laboratory of vigabatrin use when interpreting results. |
Pregnancy & contraception
- Fetal / neonatal risk
- Human vigabatrin pregnancy data are insufficient to establish risk. Animal studies found malformations and developmental neurotoxicity at clinically relevant doses.
Clinical evidence
Research summaries describe studied populations and outcomes; they do not add indications or constitute treatment recommendations.
Direct pivotal trial Guideline-supported off-label use
Trial summary
- Study design / duration
- Refractory focal-seizure approval used randomized, double-blind, placebo-controlled add-on trials. Infantile-spasm evidence included randomized dose-comparison and controlled studies with spasm cessation and video-EEG endpoints.
- Primary endpoint
- No single pivotal endpoint is identified in the cited source.
- Results
- Adult pivotal refractory focal-seizure studies showed approximately 40–50% median reductions versus little change with placebo. In infantile spasms, response varied by etiology and dose; tuberous sclerosis syndrome-associated spasms showed the strongest response.
Trial publications
Mechanism of action
- Irreversibly inhibits GABA transaminase, the enzyme responsible for GABA degradation, increasing GABA availability.
- Acts on GABA metabolism rather than the GABA-A benzodiazepine or barbiturate site; duration of effect is presumed to depend on enzyme resynthesis, not just plasma half-life.
Pharmacology
Adult values unless specified. Vd/F denotes apparent oral distribution volume.
Pharmacokinetics
- Bioavailability
- Essentially completely absorbed orally. About 80% of the administered dose is recovered in urine as unchanged drug; that recovery fraction is not its absolute bioavailability.
- Elimination half-life
- Terminal values in the U.S. label: 5.7 hours (5 months–2 years), 6.8 (3–9 years), 9.5 (10–16 years) and 10.5 (adults).
- Volume of distribution
- Mean steady-state distribution volume approximately 1.1 L/kg.
- Active metabolite(s)
- None: not significantly metabolized.
- Active-metabolite half-life
- Not applicable — no clinically established active metabolite.
- Protein binding
- None
- Metabolism / elimination
- Not significantly metabolized
Irreversible GABA-transaminase inhibition lasts beyond plasma drug elimination; recovery depends on enzyme resynthesis, not drug half-life alone.
Molecular structure
NIH PubChem structure and record ↗
Product history
- Initial U.S. approval
- 2009
- Market / formulation history
- 2009 in the U.S.
- Brands
- Sabril · Vigafyde
- Manufacturer / marketer
- Lundbeck (Sabril); Pyros (Vigafyde)
- Generic availability
- Yes (vigabatrin)
- Related drugs
- Mechanistically related to other GABA-enhancing drugs but uniquely irreversible at GABA transaminase.
Sources & review status
Representative sources are selected product labels, not an exhaustive list of generic manufacturers. Consult the exact product and formulation prescribed. Brand-name package inserts are linked separately.
Brand reference: Sabril tablets / powder ↗
Indications and DailyMed PDFs checked: 2026-09-26. Other profile sources reviewed: 2026-09-15 · label revision noted at that review: 3/2020. This is a draft reference; final review is pending.