What is the recommended initiation protocol for Vivitrol (naltrexone) treatment?

Vivitrol (Naltrexone) Initiation Protocol

Patients must be completely opioid-free for a minimum of 7-10 days before initiating Vivitrol to prevent precipitated withdrawal, which can cause severe symptoms including cardiovascular complications and seizures. 1, 2, 3

Pre-Initiation Requirements

Opioid-Free Period

• Short-acting opioids (e.g., oxycodone, hydrocodone): Minimum 7-10 days opioid-free 3
• Long-acting opioids (e.g., methadone): Up to 2 weeks may be required 3
• Buprenorphine/Sublocade: Extended waiting period of weeks to months due to prolonged half-life (43-60 days for Sublocade) 1
• Tramadol: Must also be discontinued during the opioid-free period 3

Naloxone Challenge Test (Mandatory)

Do not perform if patient shows clinical withdrawal signs or has opioids in urine 3

Intravenous route: 3

• Inject 0.2 mg naloxone
• Observe 30 seconds for withdrawal signs
• If negative, inject 0.6 mg naloxone
• Observe additional 20 minutes

Subcutaneous route: 3

• Administer 0.8 mg naloxone
• Observe 20 minutes for withdrawal signs

Positive test signs include: nausea, vomiting, sweating, tachycardia, hypertension, pupillary dilation, muscle aches, craving, anxiety, abdominal cramps 3

If test is positive: Do NOT initiate naltrexone; repeat challenge in 24 hours 3

Baseline Laboratory Testing

• Liver function tests are mandatory before initiation 4
• Assess for acute hepatitis or liver failure (absolute contraindications) 4

Initiation Dosing

For Oral Naltrexone (if transitioning to Vivitrol)

• Day 1: Start with 25 mg to assess tolerance 3
• Day 2 onward: If no withdrawal occurs, advance to 50 mg daily 3

For Vivitrol Injectable

• Standard dose: 380 mg intramuscularly once monthly 5, 6
• Administer only after successful naloxone challenge 3
• Must be combined with psychosocial support for optimal outcomes 5

Critical Contraindications

Absolute contraindications: 2, 3

• Current opioid use or dependence
• Acute hepatitis or liver failure
• Patients requiring opioid analgesics (short-term or long-term)

Perioperative considerations: 7

• Hold oral naltrexone 3-4 days before procedures requiring opioids
• Hold intramuscular Vivitrol 24-30 days after last injection before elective procedures

Precipitated Withdrawal Risk

Vivitrol will displace any residual opioids from mu-receptors, causing severe withdrawal: 1, 2

• Symptoms include severe vomiting, diarrhea, cardiovascular arrhythmias, seizures, pulmonary edema, and cardiac arrest in extreme cases 2
• Treatment is supportive only: IV fluids, anti-emetics, symptomatic management 1
• No reliable method exists to reverse naltrexone-precipitated withdrawal once it occurs 3

Special Populations

Transitioning from Buprenorphine/Methadone

• High-risk population for severe precipitated withdrawal 3
• Consider very low-dose naltrexone induction protocol: start at 0.25 mg with concurrent buprenorphine taper over 7 days 8
• This outpatient approach achieved successful Vivitrol injection in 70% of participants 8

Alcohol Dependence

• Same opioid-free requirements apply 3
• 380 mg monthly dose reduced heavy drinking days by 25% compared to placebo 6
• Particularly effective in men and those with pre-treatment abstinence 6

Monitoring After Initiation

• Liver function tests every 3-6 months due to hepatotoxicity risk 4
• Monitor for injection-site reactions, hepatic enzyme abnormalities, insomnia, hypertension 5
• Assess treatment retention and abstinence weekly initially, then monthly 8

Common Pitfalls to Avoid

• Never initiate without confirmed opioid-free period - this is the most critical error leading to precipitated withdrawal 1, 2
• Do not rely solely on patient self-report - always perform naloxone challenge 3
• Do not use in patients who may need opioid analgesics - naltrexone blocks opioid efficacy for pain management 7, 2
• Do not assume one week is sufficient after Sublocade - extended-release buprenorphine requires much longer clearance 1