The purpose of this study is to determine whether the ingestion of caffeine, Energy Drinks has an effect on perceived alcohol intoxication.

In each of the four study periods, subjects will receive one of the four study treatments in a double blind, randomised, manner. The effects of study treatment on alcohol intoxication will be determined by measurement of breath alcohol concentration and subjective effects of intoxication. Safety and tolerability will be monitored by measurement of vital signs, in particular pulse, and review of adverse events.

Inclusion Criteria:

• Healthy male volunteers
• Able and willing to comply with the requirements of the study, confirmed by written informed consent
• Aged 20 to 26 years
• Within acceptable range for weight and body mass index (70-85 kg and 21 to 25 kg/m2)
• At least 12-14 years of formal education
• In good general health as determined by medical history and screening investigations (see below)
• Taking no regular medication
• No history of psychiatric disorders
• Moderate alcohol consumption (less than 190.4 g/week) according to the Daily Drink questionnaire (Collins et a., 1985)
• "sporadic" users of Energy Drinks (fewer than 10 cans of 250 ml in the last 6 months)
• Confirmation that the general practitioner/primary care physician knows no reason that would prevent their participation
• Similar in social and demographic data, similar quality of life
• similar patterns of use of alcoholic beverages and Energy Drinks as well as quality of life (Martinez et al., 2000)
• similar level of physical activity (physical activity questionnaire) (Baecke et al., 1982)

Exclusion Criteria:

• Any condition that the investigator and/or sponsor consider might increase the risk to the volunteer or decrease the chance of obtaining satisfactory data
• Consumed 2>x>4 caffeine-containing drinks/day within 3 months of screening
• Smoked >10 cigarettes/day or equivalent within 3 months of screening
• Consumed more than 190.4 g alcohol per week, or have a history of alcohol or drug abuse or
• Consumed less than one alcoholic drink per week