Cocaine and alcohol synergism in taste aversion learning

Cocaine and alcohol, alone and in combination, were administered following saccharin presentation to female Long-Evans rats. Although there was no clear interaction between cocaine and alcohol when cocaine was given intraperitoneally, aversions induced by the drug combination when cocaine was administered subcutaneously were greater than the summed effects of the individual drugs administered alone, indicating a synergistic interaction. Cocaethylene, a toxic metabolite of cocaine and alcohol, has been suggested to mediate such synergism. To assess the role of cocaethylene in the present design, additional taste aversion assessments were performed with cocaethylene. Although cocaethylene was found to induce aversions, the summed changes in consumption from baseline produced by cocaine, alcohol and cocaethylene were less than the changes produced by the cocaine/alcohol combination, indicating that the synergistic interaction between cocaine and alcohol in the present design can not be attributed solely to summation of the effects of the individual drugs.