Vigabatrin occupies a unique position among antiepileptics with respect to its molecular action. Its mechanism is best described as:

• A Reversible competitive inhibition of GABA reuptake transporter GAT-1
• B Positive allosteric modulation of the GABA-B receptor
• C Irreversible suicide inhibition of GABA transaminase, raising synaptic GABA concentrations ✓
• D Blockade of the synaptic vesicle protein SV2A

Explanation

Vigabatrin is a structural analogue of GABA that irreversibly inactivates GABA transaminase, the enzyme that degrades GABA, thereby increasing brain GABA content. It is used for infantile spasms, particularly in tuberous sclerosis, and for refractory focal seizures. Its use-limiting toxicity is irreversible concentric visual field constriction requiring regular ophthalmologic monitoring. Tiagabine blocks GAT-1 reversibly, and levetiracetam binds SV2A.

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.