Retigabine (ezogabine), withdrawn from many markets for pigmentation of skin and retina, was mechanistically unique among antiepileptics because it:

• A Blocked AMPA receptors on postsynaptic neurons
• B Opened neuronal KCNQ (Kv7) potassium channels ✓
• C Potentiated GABA-A receptor chloride currents
• D Inhibited synaptic vesicle glutamate export

Explanation

Ezogabine is the only antiepileptic that acts as a positive allosteric opener of KCNQ/Kv7 potassium channels. Opening these channels enhances the M-current, a potassium conductance that stabilises membrane potential and reduces repetitive firing. Loss-of-function mutations in KCNQ genes themselves cause benign familial neonatal convulsions, which supports this target. AMPA blockade belongs to perampanel, and vesicular glutamate release blockade describes the presynaptic action relevant to some newer agents.

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.