Vigabatrin

Actions

Reduces GABA breakdown by irreversibly inhibiting GABA-transaminase

Metabolism

Not metabolized.

Elimination

Renal

Half-life

7-8 hours

Plasma protein binding

0%

Important side-effects

Vigabatrin can cause permanent bilateral concentric visual field constriction. Monitoring of vision by an ophthalmic professional with expertise in visual field interpretation and the ability to perform dilated indirect ophthalmoscopy of the retina is recommended.

Abnormal MRI signal changes characterized by increased T2 signal and restricted diffusion in a symmetric pattern involving the thalamus, basal ganglia, brain stem, and cerebellum have been observed in some infants treated with vigabatrin for infantile spasms.

Neurotoxicity (intramyelinic edema).

Suicidal behavior and ideation.

Anemia.

Peripheral neuropathy.

Weight gain.

Peripheral edema.

Indications

Adjunctive treatment of focal seizures with or without generalization.

Dosing recommendation

Start with 250-500 mg/day.

Increase to target dose over 1–2 weeks.

Target dose: 1000–3000 mg/day divided in 1-2 doses.

Renal impairment

Dose adjustment might be required in patients with impaired renal function and creatinine clearance <60 ml/min.

Hepatic impairment

No dose adjustment is necessary in patients with impaired hepatic function.