API

VIGABATRIN

Drug classification

Dosage form

TABLET;ORAL

API strength per dosage

500MG

Dose

Adults: Initial dose 500 mg twice daily, titrate by 500 mg/week to 1–3 g/day in 2 divided doses. Pediatrics (infantile spasms): Start 50 mg/kg/day, increase by 25–50 mg/kg every 3 days to max 150 mg/kg/day. Renal impairment: Dose adjustment required.

Mechanism of action

Irreversibly inhibits gamma-aminobutyric acid transaminase (GABA-T), the enzyme responsible for GABA degradation, resulting in increased synaptic GABA concentrations and enhanced inhibitory neurotransmission in the central nervous system.

Indications

Refractory complex partial seizures in adults, infantile spasms (West syndrome) in infants and children aged 1 month to 2 years.

Side effects

Permanent vision loss, visual field defects, drowsiness, fatigue, weight gain, edema, confusion, agitation, depression, psychosis, peripheral neuropathy, anemia, tremor, abnormal MRI changes in infants.

Pregnancy category

Category C

Precautions

Permanent vision loss risk, baseline and regular visual field monitoring, use only when benefits outweigh risks, monitor for neuropsychiatric effects, discontinue if no substantial benefit after adequate trial, caution in renal impairment, monitor for MRI brain abnormalities in infants, risk of withdrawal seizures, avoid abrupt discontinuation.

Contraindications

Hypersensitivity to vigabatrin or any excipients, history of vigabatrin-induced vision loss, pre-existing significant visual field defects.