This paper investigates the “CB1 receptors,” and identified an antagonist to that receptor, AM4113, which “effectively blocked fentanyl discrimination” in male rats. The results of the study show that “targeting CB1 receptors might be a viable approach to develop new medications for opioid use disorders.”
Read “Effects of the cannabinoid CB1-receptor neutral antagonist AM4113 and antagonist/inverse agonist rimonabant on fentanyl discrimination in male rats” and find the full list of authors in Drug and Alcohol Dependence.