The main objective of the project is to assess whether there is an interaction between the effects of ethanol and energy drinks on driving performance.

Secondary objectives include: to evaluate subjective effects (drunkenness) after administration of alcohol and energy drinks, to assess pharmacokinetics of alcohol, caffeine and taurine after alcohol and energy drinks administration and to assess if there is an increased risk of bleeding when both drinks are taken together.

Consumption of energy drinks improve psychomotor performance and alertness. These drinks contain mostly caffeine, taurine and vitamins. Its consumption associated with ethanol may reduce feelings of drunkenness as the stimulant effects of caffeine could counteract the depressing effects of ethanol on the central nervous system. Reducing the perception of intoxication may predispose the intoxicated person to engage in risky behaviors such as driving under the influence of ethanol and therefore can increase the risk of a traffic accident. Furthermore, the combination of both beverages may increase the risk of bleeding in case of injury as anticoagulant effects have been described for ethanol while antiplatelet effects have been described for caffeine and taurine. A randomized clinical trial will be performed in healthy volunteers administering 4 treatment conditions: alcohol+energy drink, alcohol+placebo of energy drink, placebo of alcohol+energy drink and placebo of alcohol+placebo of energy drink. A multiple dose will be administered separated by 1 hour.

Inclusion Criteria:

• Understand and accept the study's procedures and sign an informed consent form
• No evidence of somatic or psychiatric disorders as per past medical history and physical examination
• EKG, blood and urine tests taken before entry into the study within the normal range. Minor and transient abnormalities may be acceptable if, according to the Principal Investigator's criterion and the state of the art, they are felt to have no clinical relevance, entail no danger to the participant, and don't interfere with the product's assessment. These abnormalities and their non-relevance must be specifically justified in writing)
• Body mass index (BMI=weight/heigth2) between 19 and 27 kg/m2, weight between 50 and 100 kg
• For premenopausal females, a regular menstrual cycle of 26-32 days duration.
• Social or recreational alcohol consumption of at least 1 unit per day (or its equivalent [7 units] over the whole week) and having experienced drunkenness several times
• Regular consumption of beverages containing methylxanthines (at least 5 per week)
• Consumption of energy drinks several times previously
• Having a driving license

Exclusion Criteria:

• Evidence of a preexisting condition (including gastrointestinal, liver, or kidney disorders) that may alter the absorption, distribution, metabolism or excretion of the drug or symptoms suggestive of drug-induced gastrointestinal irritation
• Previous psychiatric disorders, alcoholism, abuse of prescription drugs or illegal substances or regular consumption of psychoactive drugs
• Having donated blood or having participated in this same study in the preceding 8 weeks, or having participated in any clinical trial with drugs in the preceding 12 weeks
• Having had any somatic disease or having undergone major surgery in the 3 months prior to inclusion in the trial
• Individuals intolerant or having experienced a severe adverse reaction to alcohol or energy drinks
• Having regularly taken medication in the month before the trial, except for vitamins, herb-based remedies, dietary supplements that if, according to the Principal Investigator or his appointed collaborators' opinion, they pose no threat to the subjects and they won't interfere with the study's objectives. Single doses of symptomatic drugs taken during the week before the experimental session will not constitute an exclusion criterion if it can be assumed that it has been completely eliminated on the day of the experimental session
• Smokers of >5 cigarettes/day
• Consumption of >20 g/day of alcohol (females) or of >40 g/day (males)
• Daily consumption of more than 5 coffees, teas, cola drinks or other stimulant or xanthine-containing beverages in the 3 months prior to inclusion in the study
• Hepatitis B, hepatitis C or human immunodeficiency virus-positive individuals
• Pregnant or lactating women, or those using hormonal or unreliable contraceptive methods during the study period. Complete abstinence, intrauterine devices, double barrier methods or a vasectomized sexual partner will be considered acceptable
• Women with amenorrhea or suffering severe premenstrual syndrome
• Individuals of Asian ascent