GLP-1 Agonism for Blocking Cocaine Euphoria and Self-Administration

The investigators plan to explore the effects of acute pre-treatment with the glucagon like peptide-1 (GLP-1) agonist, exenatide versus placebo, on the subjective (e.g., euphoric) and behavioral effects (e.g., self-administration) of cocaine in experienced, non-treatment seeking users of the drug. Additionally, the investigators plan to explore the effects of sub-chronic (5-day) treatment with exenatide as compared to placebo on the subjective (e.g., euphoric) and behavioral (self-administration) effects of cocaine in experienced, non-treatment seeking users of the drug.