Cocaethylene
When alcohol and cocaine are ingested together, the liver produces the active metabolite cocaethylene. It is produced as a result of the transesterification of cocaine by the same non-specific carboxylesterases that normally convert cocaine to benzoylecgonine, for example, in the absence of ethanol.
Cocaethylene is a non-polar structure, and can cross the blood brain barrier, where it blocks the dopamine-reuptake transporter protein in the same way that cocaine does.
The clinical importance of this metabolite has not been fully determined, but it has a longer half-life than cocaine (2.5 hours), and it is possible that it may prolong the cocaine ‘high’. (Cone et al 1993). However, Perez-Reyes et al (1992 pp. 561-2 and 1994 pp.541-550) have found that cocaethylene appearance in the blood of a cocaine/ ethanol user does nothing to alter subjective cocaine ‘highs’ or increased heart rate etc. Indeed, it appears that the interaction between cocaine and ethanol is ‘order-of-administration’ dependant. Ethanol only appears to enhance the effects of cocaine if it is ingested prior to cocaine.
The issue of cocaine/ ethanol interaction is controversial. Karch et al (1999 pp.19-23) suggest that cocaine toxicity is not enhanced by ethanol-cocaine interactions, when low concentrations of ethanol are ingested. They concede, however, that further research is required to determine the interactions of higher concentrations of ethanol with cocaine.
The US Drug Abuse Warning System (DAWN) has identified cocaine/ethanol abuse as a major cause of emergency medical admissions, and considers the concurrent use of these drugs to be the cause of increases in cocaine related morbidity and mortality, as well as giving rise to an increased risk of dual dependency and worsening of the ‘crash’ associated with chronic use. (Lee Hearn et al 1991 p.698 and da Matta Chasin et al 2000 p.2).
Epidemiological evidence of the combined abuse of cocaine and ethanol in the US estimates that 5 million people had used this combination within 1 month of the National Household Drug Survey (1985), and that 12 million had done so within the preceding year. Despite a general decline in the prevalence of cocaine use reported by the 1990 Survey, the proportion combining both substances had increased. (Perez-Reyes and Jeffcoat 1992 p.553). Data are unavailable for combined use in the UK, but it is conceivable that the increase in cocaine use in the UK will be mirrored with an increase in the combined abuse of cocaine and ethanol.
'The Forensic Pharmacology of Drugs of Abuse', Drummer O.H and ODell M (2001) Arnold Publishers ISBN 0-340-76257-8