Lamotrigine's antiepileptic mechanism primarily involves:

• A Enhancing GABAergic inhibition by positive allosteric modulation of GABA-A receptors
• B Inhibiting GABA transaminase enzyme, increasing synaptic GABA levels
• C Blocking T-type calcium channels in thalamic relay neurons
• D Blocking voltage-gated sodium channels in their inactivated state, reducing repetitive firing ✓

Explanation

Lamotrigine stabilises neuronal membranes by preferentially binding to voltage-gated sodium channels in the inactivated state, prolonging the inactivation period and reducing high-frequency repetitive firing—similar to phenytoin and carbamazepine but with a broader spectrum. It also has glutamate release-inhibiting properties. Benzodiazepines and barbiturates act at GABA-A; vigabatrin inhibits GABA transaminase; ethosuximide blocks T-type calcium channels in absence seizures.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.