Vitamin D and Cocaine Administration

This study is designed to explore the effects of acute pre-treatment with 1,25-dihydroxyvitamin D3 (calcitriol), as compared to placebo on the behavioral (e.g., attempts to self-administer and ultimate number of infusions/boluses of cocaine self-administered), neurocognitive (e.g., performance on computerized tests of reward related learning such as the probabilistic selection task or PST and probabilistic reward task or PRT), and subjective effects (e.g, computerized visual analog scale \[VAS\] ratings of euphoria/, craving, etc.) of cocaine in experienced, non-treatment seeking users of the drug.