Recommended Use and Treatment Protocol for Vivitrol (Naltrexone) in Opioid and Alcohol Dependence
Vivitrol (injectable naltrexone) is recommended as an effective treatment for both alcohol and opioid dependence when used as part of a comprehensive treatment plan that includes psychosocial support, with a standard protocol of 380 mg administered intramuscularly once monthly after complete opioid detoxification. 1, 2
Mechanism of Action
- Naltrexone functions as a competitive antagonist at mu opioid receptors, blocking the euphoric effects of opioids and reducing alcohol cravings 1
- By blocking opioid receptors, naltrexone decreases dopamine concentration in the brain and dampens activation of the reward pathway, providing time for patients to consider consequences of relapse 1, 3
Formulations and Dosing
- Vivitrol is an extended-release intramuscular formulation containing 380 mg of naltrexone, administered once monthly 1, 4
- Oral naltrexone is available as 50 mg tablets taken daily or alternatively 100 mg on Mondays and Wednesdays, and 150 mg on Fridays 1, 2
- For alcohol dependence, the standard dose is 50 mg once daily for up to 12 weeks (oral) or 380 mg monthly (injectable) 2, 5
- For opioid dependence, treatment typically begins with 25 mg oral dose to test for withdrawal reactions, then increases to 50 mg daily if well-tolerated 2
Patient Selection and Preparation
- Patients must be completely opioid-free before starting naltrexone to avoid precipitated withdrawal 1, 2
- An opioid-free interval of minimum 7-10 days is required for patients previously dependent on short-acting opioids 2
- Patients transitioning from buprenorphine or methadone may be vulnerable to withdrawal symptoms for up to 2 weeks 2
- A naloxone challenge test is recommended if there is any question of occult opioid dependence 2
Protocol for Opioid Dependence
- Vivitrol is most beneficial for highly motivated patients who cannot or do not wish to take continuous opioid agonist therapy 1, 6
- Prior to initiation, patients must complete detoxification and be opioid-free for 7-10 days 2, 4
- Administer 380 mg intramuscularly every 4 weeks 4
- Monitor for injection site reactions and hepatic enzyme abnormalities 4
- Provide concurrent psychosocial support and counseling 4, 6
Protocol for Alcohol Dependence
- Vivitrol has been shown to reduce alcohol consumption, craving, and relapse rates 1, 5
- No opioid-free period is required unless the patient has concurrent opioid dependence 2
- Administer 380 mg intramuscularly every 4 weeks 1
- Monitor liver function tests at baseline and every 3-6 months 1, 3
- Combine with psychosocial interventions such as counseling or support groups 2, 7
Monitoring and Safety Considerations
- Liver function tests should be performed at baseline and every 3-6 months due to potential hepatotoxicity at supratherapeutic doses 1, 3
- Naltrexone cannot be used in patients requiring opioids for pain control as it blocks pain relief from opioid agonists 1, 3
- For surgical patients on naltrexone, oral formulation should be held for 2-3 days prior to elective procedures if opioids are expected 1
- Extended-release naltrexone should be held for 24-30 days after the last injection before elective procedures 1
- Patients who discontinue naltrexone treatment have increased risk of opioid overdose and death due to decreased opioid tolerance 1
Treatment Duration and Outcomes
- For alcohol dependence, clinical trials demonstrated efficacy with treatment up to 12 weeks, though longer treatment may be beneficial 2, 5
- For opioid dependence, treatment duration should be individualized based on patient response and continued risk of relapse 4, 6
- Factors associated with good outcomes include appropriate intensity and duration of treatment, management of comorbid conditions, use of community-based support groups, and good medication compliance 2, 8
Common Side Effects
- Most common side effects include hepatic enzyme abnormalities, nasopharyngitis, insomnia, hypertension, influenza, and injection-site pain 4
- Nausea and vomiting are common with oral naltrexone 7
- At the recommended dosage of 50 mg/day oral or 380 mg monthly injectable, naltrexone does not appear to be hepatotoxic 7