What injectable medication, such as (intramuscular) naltrexone, is recommended for an adult patient with alcohol abuse?

Injectable Naltrexone for Alcohol Use Disorder

Injectable extended-release naltrexone (Vivitrol) 380 mg intramuscularly once monthly is the recommended injectable medication for alcohol use disorder, and must be combined with psychosocial interventions to be effective. 1

Formulation and Dosing

• The FDA-approved injectable formulation is extended-release naltrexone 380 mg administered intramuscularly once monthly 1, 2
• This long-acting formulation addresses the adherence problems that have limited the clinical utility of oral naltrexone 2
• Treatment duration in efficacy trials was 6 months (6 monthly injections), though the American College of Gastroenterology recommends 3-6 months up to 12 months for oral formulations 3, 2

Evidence for Efficacy

• In a large randomized controlled trial of 624 alcohol-dependent adults, injectable naltrexone 380 mg resulted in a 25% decrease in heavy drinking days compared to placebo (p=0.02) 2
• The medication works by blocking opioid receptors, which dampens activation of the reward pathway by alcohol, thereby decreasing excessive drinking and increasing abstinence duration 4
• Men and patients who achieved brief abstinence before treatment initiation showed greater treatment effects 2

Critical Pre-Treatment Requirements

Patients must be completely opioid-free before receiving naltrexone to avoid precipitating severe withdrawal. 5, 1

• A minimum opioid-free interval of 7-10 days is required for patients previously dependent on short-acting opioids 1
• Patients transitioning from buprenorphine or methadone may be vulnerable to precipitated withdrawal for up to 2 weeks 1
• Naltrexone should be initiated 3-7 days after the last alcohol consumption and only after withdrawal symptoms have completely resolved 5
• Naltrexone is contraindicated during acute alcohol withdrawal and provides no benefit for withdrawal symptoms - benzodiazepines remain the gold standard for managing alcohol withdrawal syndrome 5

Hepatotoxicity Concerns and Monitoring

Naltrexone carries a risk of hepatotoxicity and requires careful patient selection and monitoring. 3, 5

• Liver function tests must be obtained at baseline and every 3-6 months during treatment 5, 4
• Naltrexone is not recommended in patients with alcoholic liver disease (ALD) according to the Korean Association for the Study of the Liver 5
• The medication is contraindicated in patients with acute hepatitis or decompensated cirrhosis 5, 1
• For patients with compensated cirrhosis or hepatic impairment, consider alternative medications such as baclofen (the only medication proven safe in cirrhotic patients) or acamprosate (which has no hepatic metabolism) 3, 5

Essential Treatment Context

Injectable naltrexone is only effective when combined with comprehensive psychosocial treatment. 3, 1

• The FDA label explicitly states that naltrexone "has not been shown to provide any therapeutic benefit except as part of an appropriate plan of management for the addictions" 1
• Treatment should include 12 sessions of manualized brief counseling at minimum 6, 2
• Voluntary participation in extramural counseling (couples/family therapy) and self-help support groups (Alcoholics Anonymous) enhances outcomes 6
• Injectable naltrexone is compatible with counseling and support group participation, with 45% of patients in trials attending all counseling sessions 6

Practical Implementation

• The medication can be initiated in the hospital setting prior to discharge to facilitate treatment engagement 7
• Discontinuation rates due to adverse events were 14.1% with the 380 mg dose 2
• Common side effects include nausea, injection site reactions, headache, and dizziness 2
• Patients who discontinue naltrexone have decreased opioid tolerance and increased risk of overdose if they return to opioid use - provide overdose education 4

Alternative Injectable Options

There is no other FDA-approved injectable medication specifically for alcohol use disorder. The combination naltrexone/bupropion mentioned in obesity literature is an oral formulation and not indicated for alcohol use disorder 3.