 Alcohol dependence is a maladaptive pattern of alcohol use, leading to clinically significant impairment or distress, as manifested by at least three of a number of criteria such as tolerance, withdrawal symptoms, frequent use of alcohol in larger amounts or over longer periods than was intended, and others. Excessive intake of alcohol reduces the life span by a decade, and alcohol drinking is strongly related to mortality from liver cirrhosis, chronic pancreatitis, certain cancers, hypertension, accidents and violence. This study is planned to evaluate the efficacy and safety of as needed use of nalmefene 18.06 mg versus placebo in decreasing monthly Heavy Drinking Days HDDs and decreasing the total consumption during a period of 24 weeks in adult patients with alcohol dependence. 