The aim of the study is to assess the safety and tolerability of GSK1521498 in combination with alcohol and to determine the amount of GSK1521498 and alcohol in your blood after you have been given these together. The study will also determine whether GSK1521498 will have an effect on alcohol liking and consumption.

The study is to test a new drug which may be used for treating alcohol addiction. The drug works by inhibiting the effects of messenger molecules called opioids. These opioids are naturally produced within the human body, and are involved in controlling how much alcohol we drink and the pleasure we get from drinking alcohol. We believe that GSK1521498 might be effective in the treatment of alcohol addiction because it is well known that drugs working on similar binding sites in the brain reduce the pleasure we get from drinking alcohol. As alcohol can effect the way that a drug is metabolised in the body, The investigators need to determine that it is safe to take GSK1521498 in combination with alcohol. and to determine the amount of GSK1521498 and alcohol in your blood after you have been given these together. The study will also determine whether GSK1521498 will have an effect on alcohol liking and consumption.

Inclusion Criteria:

• healthy male or female between 21 and 55 years of age inclusive.
• within 20% normal weight for height and body build.
• A female subject of child-bearing potential must use one of the contraception methods listed in the protocol prior to the start of the study until at least 14 days after receiving the last dose of study medication.
• Male subjects must agree to use one of the contraception methods listed in the protocol from the time of the first dose of study medication until at least 5 days after receiving the last dose of study medication.
• History of regular alcohol consumption within 6 months of study.
• No recent changes in patterns of alcohol consumption.
• Capable of giving written informed consent, which includes compliance with the requirements and restrictions listed in the consent form.

Exclusion Criteria:

• A positive test for HIV, Hep B or Hep C.
• Current or chronic history of liver disease.
• Current or chronic history of neurological disorders.
• Subjects with previous or current psychiatric history.
• Past history of DSM-IV alcohol dependence or abuse.
• Binge drinking more than once a week (>5 standard drinks in one session is a binge).
• Currently trying to quit alcohol.
• Positive urine screen for amphetamines, barbiturates, cocaine, opiates, cannabinoids or bezodiazepines at screening.
• Regular consumption of >450mg caffeine per day (an average cup contains about 75mg).
• Heavy smokers, defined as those who smoke >10 cigarettes a day. Also those who cannot abstain during the admission period.
• Use of prescription or non-prescription drugs, including vitamins, herbal and dietary supplements (including St John's Wort) within 14 days prior to the first dose of study medication.
• Pregnant or lactating females.
• QTcB or QTcF >450msec.
• Participated in a clinical trial and has received an investigational product within 30 days, 5 half-lives or twice the duration of the biological effect of the investigational product.
• Where participation in the study would result in donation of blood or blood products in excess of 500mL within a 56 day period.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.