Which antiepileptic drug acts by inhibiting the GAT-1 GABA transporter in presynaptic neurons, thereby prolonging the synaptic action of released GABA?

• A Felbamate
• B Retigabine (ezogabine)
• C Zonisamide
• D Tiagabine ✓

Explanation

Tiagabine is a nipecotic acid derivative that selectively blocks the neuronal GAT-1 transporter responsible for GABA reuptake, increasing extracellular GABA. Retigabine opens KCNQ (Kv7) potassium channels, zonisamide blocks sodium channels and has weak carbonic anhydrase inhibition, and felbamate antagonises NMDA receptors and modulates sodium channels. Felbamate is reserved for Lennox-Gastaut syndrome because of fatal aplastic anaemia and hepatotoxicity, a separate high-yield fact.

Reference: Goodman and Gilman's The Pharmacological Basis of Therapeutics, 13th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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