Sodium valproate is effective across multiple seizure types. Its primary mechanism of action at the molecular level involves:

• A Selective blockade of T-type calcium channels in thalamic neurons
• B Blocking inactivated voltage-gated sodium channels only
• C Multiple mechanisms: sodium channel blockade, GABA enhancement (via GABA-T inhibition), and T-type calcium channel blockade ✓
• D Allosteric potentiation of GABA-A receptor chloride conductance

Explanation

Valproate has a broad-spectrum mechanism including: blockade of voltage-gated sodium channels in their inactivated state, inhibition of GABA transaminase (GABA-T) increasing synaptic GABA levels, and weak blockade of T-type calcium channels in thalamic neurons relevant to absence seizures. This multiplicity of mechanisms explains its efficacy across focal, generalized tonic-clonic, and absence seizures. Pure T-type calcium channel blockade is the primary mechanism of ethosuximide.

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

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Written and medically reviewed by the StethoPrep medical team.