INTRODUCTION: Alcohol and cocaine are frequently used simultaneously, with alcohol typically consumed prior to cocaine. Qualitative studies indicate that this combination enhances and prolongs euphoria compared to cocaine alone. The aim of this study is to collect quantitative data that were published several decades ago, but have never been integrated.

METHODS: A narrative and integrative review was conducted to collect and synthetize research data from quantitative controlled human studies on the mechanisms responsible for enhanced and prolonged euphoric sensations during co-use of alcohol and cocaine compared to cocaine-alone. A total of 1,012 unique studies were retrieved via Medline (PubMed), Embase, PsycInfo, and Google Scholar of which 24 studies published between 1987-2011 met the eligibility criteria.

RESULTS: The current narrative and integrative review shows that the co-use of alcohol and cocaine potentiates and prolongates cocaine's euphoric effects. First, when alcohol is used prior to oral or intranasal cocaine, it inhibits cocaine metabolism, resulting in higher peak plasma levels (+18-52%) and increased bioavailability (+15-40%) of cocaine. Second, alcohol plus cocaine generates cocaethylene (12-34% conversion) which, compared to cocaine, induces a similar or somewhat less intense but more prolonged euphoria. Third, in contrast to cocaine, cocaethylene selectively inhibits dopamine reuptake resulting in higher synaptic dopamine levels, which may explain its greater reinforcement compared to cocaine.

CONCLUSION: Co-use of alcohol and cocaine enhances and prolongs the subjective and reinforcing effects of cocaine. Although this may be perceived as an efficient way of drug use, it also poses serious cardiovascular risks.