Which medication theoretically reduces glutamate release by inhibiting voltage-sensitive sodium channels, and is used in the treatment of bipolar disorder?

A. Levetiracetam: Levetiracetam primarily binds to the synaptic vesicle protein SV2A, modulating neurotransmitter release, but its effect on bipolar disorder is not well established. Its action on sodium channels is indirect and not the primary mechanism used in mood stabilization. B. Amantadine: Amantadine acts as a weak NMDA receptor antagonist and promotes dopamine release. While it may influence glutamate indirectly, it is not a standard treatment for bipolar disorder or for reducing glutamate via sodium channel inhibition. C. Pregabalin: Pregabalin binds to voltage-gated calcium channels, reducing excitatory neurotransmitter release. It is used mainly for neuropathic pain and anxiety, not as a primary treatment for bipolar disorder. D. Valproate: Valproate stabilizes mood in bipolar disorder by inhibiting voltage-sensitive sodium channels, which reduces excessive glutamate release and neuronal excitability. This mechanism contributes to its efficacy in treating both manic and mixed episodes.