Which antiepileptic acts by irreversibly inhibiting GABA transaminase, thereby increasing brain GABA concentrations, and requires periodic visual field testing because of retinal toxicity?

• A Tiagabine
• B Rufinamide
• C Retigabine
• D Vigabatrin ✓

Explanation

Vigabatrin forms an irreversible covalent adduct with GABA transaminase (GABA-T), the enzyme that degrades GABA. Irreversibility means effect persists until new enzyme is synthesised. It is first-line therapy for infantile spasms, especially those due to tuberous sclerosis. Concentric visual field constriction is its limiting toxicity, mandating ophthalmologic monitoring. Tiagabine blocks GABA reuptake through GAT-1 instead, and retigabine opens KCNQ potassium channels.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.