In all forms of naltrexone, euphoria and sedation are stopped by stopping the effects of central nervous system depressants. In place of the intoxicating substances, the medicine binds to those receptor sites and stays there for a long time. After detoxing, naltrexone won't bind to opioid receptor sites, so when the user relapses, his or her use of the substance won't result in a high. Vivitrol is administered intramuscularly once a month. Taking naltrexone on a daily basis was difficult due to medication compliance; patients needed to remember to take the pills every day. Once-a-month injections reduce medication compliance factors in the treatment plan.