Although the mechanism of action of valproate is not fully understood,  traditionally, its anticonvulsant effect has been attributed to the blockade of voltage-gated sodium channels and increased brain levels of gamma-aminobutyric acid (GABA).  The GABAergic effect is also believed to contribute towards the anti-manic properties of valproate.  In animals, sodium valproate raises cerebral and cerebellar levels of the inhibitory synaptic neurotransmitter, GABA, possibly by inhibiting GABA degradative enzymes, such as GABA transaminase , succinate-semialdehyde dehydrogenase and by inhibiting the re-uptake of GABA by neuronal cells. 
Additionally, the WADA list of prohibited substances is not definitive. By necessity the list identifies classes of prohibited substances, such as anabolic agents and related substances and prohibited methods only, rather than publishing a full list of substances. When analyzing a supplement product for contaminants the Prohibited List is unable to act as a checklist for all prohibited substances against which products should be screened — supplement analysis cannot guard against contamination using untried, untested and unknown designer drugs.