The purpose of this study is to evaluate the combined effects of the study medications naltrexone and memantine on alcohol drinking behaviors. Participants will be randomized to receive a combination of these medications over a one week period and then participate in a laboratory session. During this session, participants are given an initial drink of alcohol followed by the choice to drink up to 12 more drinks over a three-hour period. These medications are hypothesized to reduce craving and number of drinks consumed prior to and after exposure to the initial drink of alcohol and during the three hour drinking period.