New research has learned that naltrexone is not an effective treatment for alcohol dependence for women and other people who have a specific genotype. “Naltrexone is one of the few medications approved for treating alcoholism,” said Marco Leyton, the author of the study. “Naltrexone does not work for everyone, though.” “Naltrexone is a very specific drug that only acts on opioid receptors,” said Charles P. O’Brien, of the University of Pennsylvania. “A significant percentage of alcoholics receive opioid stimulation when they drink alcohol and this produces good feelings such as euphoria. If they take naltrexone, they don’t feel so much euphoria. While this doesn’t cure their alcoholism, it makes them more responsive to treatment. They don’t stop drinking right away, but they drink less. Thus, naltrexone goes well with 12-step programs and behavior therapy.” While naltrexone has held promise for many people for the treatment of alcohol dependence, this finding is startling and will affect many people. “The study found that the medication decreased alcohol euphoria most clearly in two groups: women, and people with a gene related to the endorphin system,” said Leyton.