The overall goal of this project is to develop initial human data on effects of novel compounds on safety (interactions with oxycodone) and efficacy (subjective response to oxycodone) in non-treatment seeking opioid use disorder subjects. The compound to be studied will be the 5-HT2CR agonist lorcaserin. There are no known or reported adverse interactions between lorcaserin and oxycodone or other opioids.