1) Opioid antagonist 
Nalmexone (INN; EN-1620A, UM-592), or nalmexone hydrochloride (USAN), is a semisynthetic, mixed opioid agonist-antagonist with analgesic and narcotic antagonist properties that was never marketed. In clinical studies it was found to have comparable analgesic efficacy to morphine, though with several-fold reduced potency. In addition, nalmexone`s ....