Vigeding Vigabatrin Powder for Oral Solution

1. Indications and Usage
Infantile Spasms (IS):
Treatment of patients 1 month to 2 years of age with Infantile Spasms, when the potential benefit outweighs the risk of vision loss.
Note: Particularly effective in cases associated with Tuberous Sclerosis Complex (TSC).
Refractory Complex Partial Seizures (CPS):
Treatment of adult patients with CPS who have failed adequate trial of at least two other antiepileptic drugs.
Note: Due to the risk of permanent vision loss, this indication is restricted to patients who cannot respond satisfactorily to other treatments.
2. Dosage and Administration
Route of Administration:
For Oral Use ONLY.
Recommended Dosage:
Infantile Spasms (Pediatrics):
Starting Dose: 50 mg/kg/day (administered in two divided doses).
Titration: Can be titrated up to 150 mg/kg/day based on clinical response.
Refractory CPS (Adults):
Starting Dose: 1000 mg/day (administered in two divided doses).
Titration: Can be titrated up to 3000 mg/day.
Administration:
Dissolve the powder in water before administration.
Do not mix with hot liquids or food.
3. Mechanism of Action
GABA-T Inhibition:
Vigabatrin is a structural analog of GABA (gamma-aminobutyric acid).
Irreversible Enzyme Blocking:
It acts as an irreversible inhibitor of GABA-transaminase (GABA-T), the enzyme responsible for the metabolism/breakdown of GABA.
Increasing GABA Levels:
By blocking GABA-T, vigabatrin increases the concentration of GABA (the major inhibitory neurotransmitter) in the brain, thereby stabilizing neuronal electrical activity and preventing seizures.
4. Safety and Warnings
Vision Loss (Boxed Warning):
Vigabatrin causes permanent damage to the retina (constricting the visual field), which occurs in both adults and children.
Restriction: Due to this risk, the drug is only available through a restricted distribution program (SHARE program in the US).
Monitoring: Vision testing (e.g., visual field tests) is required at baseline and at regular intervals.
Abnormal MRI Signals:
In infants, vigabatrin can cause abnormal MRI signals (transient intramyelinic edema) in the brain.
Neurotoxicity:
Signs of neurotoxicity (e.g., hypotonia, seizures) have been observed in animal models.
Suicidal Behavior:
Antiepileptic drugs (AEDs) increase the risk of suicidal thoughts or behavior.
Withdrawal Syndrome:
Avoid abrupt discontinuation; tapering is recommended to prevent seizures.
5.Adverse Reactions
Most Common (Infants):
Somnolence, bronchitis, otitis media, diarrhea, vomiting, and irritability.
Most Common (Adults):
Dizziness, fatigue, headache, nervousness, ataxia, depression, and nystagmus.
6.Drug Interactions
Phenytoin:
Vigabatrin may decrease the plasma concentration of Phenytoin (by approx. 16–30%). Monitoring of Phenytoin levels is recommended.
Other AEDs:
No significant interactions observed with Carbamazepine, Phenobarbital, or Valproate.
7.Pharmaceutical Information
Chemical Composition:
Active Ingredient: Vigabatrin.
Available Strength: 500 mg packets (single dose).
Appearance: White to off-white powder.
Storage: Store at 20°C to 25°C (68°F to 77°F).