Naltrexone

Administration

• Type: Opioid antagonist
• Dosage Forms:
• Routes of Administration: PO, IM
• Common Trade Names: ReVia, Vivitrol, Depade

Adult Dosing

• Opioid dependence (prevention of relapse after opioid-free x 7-10d), ETOH dependence: 25-50mg PO daily OR 380mg IM q4w

Pediatric Dosing

Safety/efficacy not established

Special Populations

Pregnancy Rating

• Category C

Lactation risk

• Minimally excreted in breastmilk

Renal Dosing

• Use caution

Hepatic Dosing

• Use caution

Contraindications

• Allergy to class/drug
• Patients who are on opioid analgesics/partial agonists, are opioid-dependant, or in acute opioid withdrawal

Adverse Reactions

Serious

• Depression, suicide, and suicidality
• Vulnerability to opioid overdose: Patients should be alerted that they may be more sensitive to opioids, even at lower doses, after discontinuance of naltrexone
• Hepatotoxicity
• Severe injection-site reactions (e.g. necrosis, cellulitis, hematoma)

Common

• Injection site reaction
• Nausea/vomiting, diarrhea, decreased appetite, dry mouth
• LFT abnormalities,
• Elevated CPK
• Headache, dizziness, anxiety, insomnia, somnolence
• URI, pharyngitis
• Arthralgia, muscle cramps, back pain
• Rash

Pharmacology

• Half-life: PO- 4-13h;IM- 5-10 days
• Metabolism: Hepatic
• Excretion: Urinary

Mechanism of Action

• Potent nonselective opioid competitive receptor antagonist
• Reduces the rewarding effects of alcohol consumption by inhibiting the activity of endogenous opioids in the mesolimbic system.

See Also

• Opioids