Naltrexone is the name of a medication that counteracts the effects of opioid narcotic drugs and medications inside the brain and body. Doctors commonly use the medication to help opioid-addicted people stay drug-free during recovery. In a study published in November 2013 in the journal Drug and Alcohol Dependence, an American research team assessed the effectiveness of one particular form of naltrexone, called Depotrex, as an opioid addiction treatment. These researchers concluded that the medication\u2019s usefulness is only confirmed when it\u2019s used in sufficiently high dosages. Naltrexone Basics Chemically, naltrexone is known as an opioid antagonist. This means that it stops both legal and illegal opioid substances from producing the brain function alterations responsible for producing a narcotic \u201chigh.\u201d Experts in the field sometimes refer to this action as a \u201cblockade\u201d effect. Because naltrexone counteracts the effects of opioids so rapidly, doctors can\u2019t give it to people who currently have narcotics circulating in their systems. If these individuals received the medication, they would undergo severe forms of drug withdrawal due to the sudden establishment of an opioid blockade. Instead, doctors introduce naltrexone in small amounts to people in opioid addiction recovery who have firmly entered drug abstinence. Doctors typically give their patients naltrexone as long as they feel that there are significant risks for a relapse and a return to active opioid use. Depending on the individual, this may mean that the medication is prescribed for as little as a few days or for as long as years. Since naltrexone is not an opioid or any other form of addictive substance, people who stop using it run no risk of undergoing drug withdrawal, a situation that can potentially occur in individuals who take either of two other common opioid addiction medications called methadone and buprenorphine. In addition to injectable Depotrex (or another injectable form of naltrexone called Vivitrol), the medication may come in pill forms called Depade and ReVia. Current Findings In the study published in Drug and Alcohol Dependence, researchers from Columbia University and the New York State Psychiatric Institute compared the effectiveness of long-acting naltrexone (Depotrex) injections to the effectiveness of an injected placebo medication with no known benefit for opioid addiction treatment or the treatment of any other condition. Some of the individuals enrolled in the study received relatively low doses of Depotrex (192 mg), while others received relatively large doses of the medication (384 mg). The placebo recipients, low-dose naltrexone recipients and high-dose naltrexone recipients all underwent eight weeks of treatment. In order to avoid any bias in the results, neither the participants nor the researchers learned until the study ended who received which treatment. The researchers used urine drug testing to assess naltrexone\u2019s treatment effectiveness. They hypothesized that the participants with opioids in their system would not stick with treatment over time, and therefore would not recover from their addictions. The results of the study partially confirmed this hypothesis: Both the placebo recipients and the low-dose naltrexone recipients tested positive for opioids with some frequency, and tended to subsequently drop out of treatment. However, when the high-dose naltrexone recipients tested positive for opioid drug use, they tended not to drop out of treatment. Instead, they were more apt to return to drug abstinence and complete their treatment programs. In comparison to the study participants taking a placebo, the recipients of both low-dose and high-dose naltrexone had a significantly improved rate of ongoing treatment participation when they remained drug-free. Significance and Considerations The authors of the study published in Drug and Alcohol Dependence confirm the effectiveness of long-acting naltrexone as treatment for recovering opioid addicts. However, they specifically tie the usefulness of the medication to the receipt of adequate dosages during the recovery process. In particular, they point out, when people on inadequate doses of the medication \u201ctest the naltrexone blockade\u201d and attempt to use opioids (an act counter to the purposes of naltrexone treatment), they will likely end their treatment participation. Conversely, when people on adequate doses of the medication attempt to use opioids, they will likely successfully rebound from these attempts and return to drug sobriety. On a separate note, while naltrexone does not consistently address the drug cravings that help define opioid addiction, the study\u2019s authors believe that cessation of cravings may help explain the benefits of the medication for recovering addicts who never attempt to use opioids after initially gaining abstinence.