Nalmefene (originally known as nalmetrene; trade name Selincro) is an opioid antagonist used primarily in the management of alcohol dependence. It has also been investigated for the treatment of other addictions such as pathological gambling. Nalmefene is an opiate derivative similar in both structure and activity to the opioid antagonist naltrexone. Advantages of nalmefene relative to naltrexone include longer half-life, greater oral bioavailability, and no observed dose-dependent liver toxicity.