What is Vivitrol (naltrexone) used for in adults with a history of alcohol dependence and potential liver disease?

What is Vivitrol?

Vivitrol is a 380-mg monthly intramuscular injection of extended-release naltrexone, an opioid antagonist FDA-approved for treating both alcohol dependence and opioid dependence by blocking opioid receptors and reducing alcohol craving. 1, 2

Mechanism of Action

• Naltrexone functions as a mu opioid receptor antagonist that blocks the euphoric effects of opioids and reduces the reinforcing effects of alcohol 1, 3
• By blocking opioid receptors, it prevents impulsive substance use and provides time for patients to consider relapse consequences and seek support 1
• The medication reduces alcohol craving and decreases the "high" experienced while drinking 4

FDA-Approved Indications

• Alcohol dependence: Vivitrol is widely used for treating alcohol dependence and must be part of a comprehensive management plan that includes psychosocial interventions 1, 2
• Opioid dependence: FDA-approved for opioid dependence, particularly effective in motivated populations such as healthcare professionals 1, 2

Clinical Efficacy

Alcohol Dependence

• The 380-mg monthly injection reduces heavy drinking days by 25% compared to placebo (p=0.02) 5
• Naltrexone has a number needed to treat of approximately 20 to prevent return to any drinking 6
• Clinical trials demonstrate that naltrexone supports abstinence, prevents relapse, and decreases alcohol consumption when combined with psychosocial support 2

Opioid Dependence

• Produces complete blockade of euphoric effects of opioids in both volunteer and addict populations 2
• Most effective in good prognosis opioid addicts who take the drug as part of comprehensive occupational rehabilitative programs or behavioral contracts 2

Advantages of Injectable Formulation

• The monthly injection addresses the critical problem of poor medication compliance seen with daily oral naltrexone 3, 5
• Provides reliable naltrexone release at therapeutic levels for 1 month 3
• Discontinuation rates due to adverse events are similar to placebo (14.1% for 380-mg vs 6.7% for placebo) 5

Critical Safety Considerations in Liver Disease

Hepatotoxicity Concerns

• Naltrexone has been associated with hepatocellular injury at supratherapeutic doses (up to 300 mg/day), but not at the recommended 50 mg daily or 380 mg monthly doses 2
• The American Association for the Study of Liver Diseases recommends naltrexone 50 mg once daily only for patients with normal liver function 6
• Extended-release naltrexone at recommended clinical doses does not appear hepatotoxic in actively drinking alcohol-dependent patients 7

Monitoring Requirements

• Baseline liver function tests are required before initiating treatment 1
• Liver function tests should be repeated every 3-6 months during treatment 1
• Recent evidence suggests naltrexone is safe in patients with compensated cirrhosis, with liver enzymes actually decreasing during treatment 8

Contraindications in Liver Disease

• Naltrexone should be avoided in patients with severe alcoholic liver disease due to hepatotoxicity risk 1, 9, 10
• The American Association for the Study of Liver Diseases recommends against using naltrexone in patients with alcoholic liver disease 9, 10
• For patients with liver disease, baclofen is the preferred medication as it is the only agent specifically studied and proven safe in this population 6, 10

Critical Contraindications

• Cannot be used in patients currently taking opioids as it will precipitate severe withdrawal symptoms 1, 2
• Contraindicated in patients requiring opioid pain management, as it blocks pain relief from opioid agonists 1
• Patients must be opioid-free for 7-10 days before initiating naltrexone to avoid precipitated withdrawal 2

Common Adverse Effects

• Most common side effects include nausea (10%), headache (7%), dizziness (4%), nervousness (4%), and fatigue (4%) 2
• Adverse effects are generally mild and transient 3
• Some patients may experience an opioid withdrawal-like symptom complex consisting of tearfulness, mild nausea, abdominal cramps, restlessness, and myalgia 2

Essential Treatment Context

• Vivitrol is not a standalone treatment and has not been shown to provide therapeutic benefit except as part of an appropriate comprehensive management plan 2
• Must be combined with psychosocial interventions such as cognitive-behavioral therapy, motivational interviewing, Alcoholics Anonymous, or professional counseling programs 1, 2
• The medication is most effective when given under conditions that enhance patient compliance and external support 2