Acamprosate was the third medication, after disulfiram and naltrexone, to receive U.S. Food and Drug Administration (FDA) approval for postwithdrawal maintenance of alcohol abstinence. The French pharmaceutical company Laboratoires Meram began clinical development and testing of acamprosate in 1982. From 1982 to 1988, acamprosate was tested for safety and for efficacy as a treatment for alcohol dependence. Based on these studies, in 1989 Laboratoires Meram was granted marketing authorization for acamprosate in France under the trade name Aotal®. Since then, acamprosate has been extensively used and studied throughout Europe and, subsequently, in the United States. Although acamprosate has been used in Europe for more than 20 years, it was not approved by FDA until July 2004. Acamprosate became available for use in the United States in January 2005, under the trade name Campral® Delayed-Release Tablets (Merck Santé, a subsidiary of Merck KGaA, Darmstadt, Germany). Campral is currently marketed in the United States by Forest Pharmaceuticals. 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.