What is the mechanism of action of valproic acid?

Valproic acid primarily works by increasing the concentration of gamma-aminobutyric acid (GABA) in the brain, which is a key inhibitory neurotransmitter. One of the mechanisms by which it achieves this is by inhibiting the enzyme GABA transaminase. This enzyme is responsible for the breakdown of GABA, so by inhibiting it, valproic acid effectively increases the levels of GABA available in the synaptic cleft. This increased concentration enhances GABAergic neurotransmission, leading to a more significant inhibitory effect on neuronal excitability.

This mechanism is particularly relevant in the treatment of epilepsy and mood disorders, where the balance between excitatory and inhibitory neurotransmission is crucial for maintaining proper brain function. The action of valproic acid in boosting GABA levels is integral to its therapeutic effects, which include stabilizing mood and controlling seizure activity.