Acamprosate ( C5H11NO4S ) also known by the brand name Campral™, is a widely used drug used for treating alcohol dependence. It's now an over-the-counter medicine.
It's thought to stabilize chemical signalling in the brain that would otherwise be disrupted by alcohol withdrawal. Possibly by blocking glutaminergic N-methyl-D-aspartate receptors (while gamma-aminobutyric acid type A receptors are activated).
But the precise mechanism of action is currently unknown.
The mechanism of action of acamprosate in maintenance of alcohol abstinence is not completely understood. Chronic alcohol exposure is hypothesized to alter the normal balance between neuronal excitation and inhibition. in vitro and in vivo studies in animals have provided evidence to suggest acamprosate may interact with glutamate and GABA neurotransmitter systems centrally, and has led to the hypothesis that acamprosate restores this balance. It seems to inhibit NMDA receptors while activating GABA receptors.
Further info DrugBank