What is the typical dosage and treatment regimen for Naltrexone in adults with a history of opioid or alcohol dependence?

Naltrexone Dosing and Treatment Regimen for Opioid and Alcohol Dependence

Standard Dosing Protocol

For both opioid and alcohol dependence, the standard naltrexone dose is 50 mg orally once daily, or alternatively 380 mg intramuscular injection (Vivitrol) administered monthly. 1, 2

Oral Naltrexone Dosing Options

• Daily regimen: 50 mg once daily is the standard approach for most patients 1, 2
• Alternative flexible regimen: 100 mg on Mondays and Wednesdays, with 150 mg on Fridays, which may improve adherence in supervised settings 1
• Initial dose for opioid dependence: Start with 25 mg on day one; if no withdrawal signs occur, advance to 50 mg daily thereafter 2

Injectable Naltrexone (Vivitrol)

• Dose: 380 mg intramuscular injection administered monthly 1
• Administration site: Gluteal muscle, alternating sides with each injection 3
• FDA approval: Approved for both alcohol and opioid dependence 1

Critical Pre-Treatment Requirements

Patients must be completely opioid-free for a minimum of 7-10 days before initiating naltrexone to avoid precipitating severe, potentially life-threatening withdrawal. 2, 1

Opioid-Free Period Requirements

• Short-acting opioids (oxycodone, hydrocodone, heroin): Minimum 7-10 days opioid-free 2, 4
• Buprenorphine or methadone: Patients may be vulnerable to precipitated withdrawal for up to 2 weeks after discontinuation 2
• Tramadol: Must also be discontinued before starting naltrexone 2

Naloxone Challenge Test

Before initiating naltrexone, consider performing a naloxone challenge test if there is any question of occult opioid dependence 2:

Intravenous route:

• Inject 0.2 mg naloxone IV, observe for 30 seconds
• If no withdrawal signs, inject 0.6 mg naloxone
• Observe for additional 20 minutes 2

Subcutaneous route:

• Administer 0.8 mg naloxone subcutaneously
• Observe for 20 minutes for withdrawal signs 2

Critical interpretation: If any withdrawal signs appear (nausea, vomiting, sweating, pupillary dilation, anxiety, muscle aches), the test is positive—do NOT initiate naltrexone and repeat challenge in 24 hours 2

Treatment Duration and Context

Naltrexone should be prescribed for at least 12 weeks as demonstrated in efficacy trials, though many clinicians recommend one year of continuous treatment. 2, 5

• The placebo-controlled trials demonstrating efficacy used naltrexone 50 mg daily for up to 12 weeks 2
• Extended treatment duration (one year) is commonly recommended in clinical practice, though not systematically studied 5
• Naltrexone must be combined with comprehensive psychosocial treatment—medication alone is insufficient 2, 1

Patient Selection Criteria

Naltrexone is most beneficial for highly motivated patients who cannot or do not wish to take continuous opioid agonist therapy (buprenorphine or methadone). 1

Ideal Candidates

• Healthcare professionals and other highly motivated populations 1
• Patients preferring opioid-free treatment over maintenance therapy 1
• Criminal justice populations (particularly with injectable formulation) 1
• Patients with alcohol dependence who have completed detoxification 2

Contraindications

• Absolute contraindications: Patients currently using opioids, acute hepatitis, decompensated cirrhosis 1, 2
• Relative contraindications: Patients requiring opioid analgesia for pain management 1
• Pregnancy: Do not use naltrexone; offer buprenorphine or methadone instead 1, 3

Safety Monitoring Requirements

Obtain baseline liver function tests and repeat every 3-6 months due to potential hepatotoxicity at supratherapeutic doses. 1, 4

• Naltrexone at standard 50 mg daily dose has not shown clinically significant hepatotoxicity 6, 5
• Most common adverse effects are nausea and vomiting, typically mild and transient 7, 6
• Critical warning: Patients who discontinue naltrexone have markedly increased risk of opioid overdose and death due to decreased opioid tolerance 1

Perioperative Management

For patients requiring elective surgery with anticipated opioid use:

• Oral naltrexone: Hold for 2-3 days prior to procedure 1, 4
• Extended-release naltrexone (Vivitrol): Hold for 24-30 days after last injection 1, 4
• Inform anesthesiologist of naltrexone use and timing of last dose 4
• Consider alternative pain management strategies (regional anesthesia, non-opioid analgesics) 1

Common Clinical Pitfalls

• Never initiate naltrexone in patients still using opioids—this precipitates severe withdrawal and causes treatment dropout 2, 3
• Do not rely solely on patient self-report of opioid abstinence—perform urine drug screen and consider naloxone challenge 2
• Do not prescribe naltrexone without concurrent behavioral therapy—medication alone has limited efficacy 2, 1
• Do not use naltrexone as first-line for opioid use disorder—buprenorphine and methadone have stronger evidence for preventing relapse 1
• Warn patients about overdose risk if they discontinue naltrexone and return to previous opioid use, as tolerance will be markedly reduced 1, 4