The investigator and clinical research coordinator (CRC) explained the study procedures to each subject. At each visit, they also provided details of the schedule for the next visit. An independent investigational drug allocation controller, who was affiliated neither with a participating medical institution nor with the sponsor, carried out blinding of the investigational drugs. The investigational drugs were numbered and then delivered to the participating institutions. At each institution, the investigational drugs in press-through-package sheets were handed in numerical order to the subjects at the time of discharge and at each visit (Table 1). Subjects were administered acamprosate 1,998 mg/d or placebo orally for 24 weeks beginning on the day of discharge after completion of inpatient therapy, followed by a further 24-week follow-up period. Two tablets of the investigational drug (333 mg of placebo) were to be administered after meals 3 times per day. The primary endpoint was complete abstinence. The investigators remained blinded to the group allocation of those who dropped out throughout the study. Figure 1 shows the study schedule, including study visits and observational parameters. The study was performed between 2009 and 2011.