what is naltrexone
319 Reviews. Naltrexone is the generic form of the brand-name drug Vivitrol, which is used to prevent substance abuse in people who have been addicted to alcohol or opioid pain medications.Examples of opioid painkillers include Norco (hydrocodone/acetaminophen), OxyContin (oxycodone), and codeine.lthough primarily an oral drug taken in pill form, naltrexone implants, which are inserted into the lower abdominal wall under local anesthetic, have been used to treat opioid addiction and/or abuse/misuse. Implants release a controlled amount of naltrexone into the body and are effective for three to six months.