Treatment options for alcohol dependence have several mechanisms of action, including prevention of alcohol consumption, minimization of craving and withdrawal, and reduction of positive reinforcement. Naltrexone, a MOR antagonist, is also able to reduce relapse to heavy drinking and the frequency of alcohol consumption [106, 107]. Naltrexone prevents the activation of MOR by endogenous opioids, leading to decreases in the euphoria and subsequent attenuation of positive reinforcement associated with alcohol use. Over time patients experience reduced levels of craving for alcohol and gradually consume less alcohol (reviewed in [108]). Naltrexone did not increase rates of abstinence in nearly all the double-blind placebo-controlled trials.
