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. 
Ciba reportedly patented boldenone in 1949.  It subsequently developed several experimental esters of the drug in the 1950s and 1960s.  One of these was boldenone undecylenate, which was introduced for clinical use under the brand name Parenabol and saw some use in the late 1960s and early 1970s.  However, it was discontinued before the end of the 1970s.  Subsequently, boldenone undecylenate was introduced by Squibb under the brand name Equipose for veterinary use, most commonly in horses.