Vigabatrin exerts its antiepileptic action by:

• A Positive allosteric modulation of the GABA-A receptor chloride channel
• B Blockade of the synaptic GAT-1 GABA transporter
• C Irreversible inhibition of GABA transaminase, raising brain GABA levels ✓
• D Selective blockade of T-type calcium channels in thalamic neurons

Explanation

Vigabatrin is a structural analogue of GABA that irreversibly inhibits GABA transaminase (GABA-T), the enzyme that degrades GABA, thereby increasing CNS GABA concentrations. It is used for infantile spasms and refractory focal seizures. Option B describes tiagabine, option A describes benzodiazepines and barbiturates, and option D describes ethosuximide. Its limiting toxicity is irreversible concentric visual field constriction, requiring periodic visual field testing during therapy.

Reference: Katzung Basic and Clinical Pharmacology, 15th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.