Comparative Pharmacology
Head-to-head clinical analysis: NALOXONE HYDROCHLORIDE AUTOINJECTOR versus VIVITROL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NALOXONE HYDROCHLORIDE AUTOINJECTOR versus VIVITROL.
NALOXONE HYDROCHLORIDE (AUTOINJECTOR) vs VIVITROL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Competitive antagonist at mu, kappa, and delta opioid receptors, reversing opioid-induced respiratory depression and analgesia.
Naltrexone, as the active moiety of VIVITROL, is a competitive antagonist at opioid receptors (mu, kappa, and delta), blocking the euphoric effects of alcohol and opioids. It also modulates the hypothalamic-pituitary-adrenal axis and dopamine pathways implicated in alcohol craving.
Initial: 0.4 mg or 2 mg intramuscularly (IM) or subcutaneously (SC); may repeat every 2-3 minutes as needed. For autoinjector: 2 mg single dose, administer IM or SC into anterolateral thigh; may repeat every 2-3 minutes with a new device if no response. Max total dose: 10 mg.
380 mg intramuscularly every 4 weeks, alternating gluteal injections.
None Documented
None Documented
Terminal elimination half-life approximately 1 to 1.5 hours in adults. In neonates, half-life is prolonged (about 3 hours). Clinical context: due to short half-life, repeated doses or continuous infusion may be needed for opioid overdose with long-acting opioids.
Naltrexone terminal half-life: 4-13 hours (mean 9.7 h). Active metabolite 6-β-naltrexol: 10-15 hours. Clinically, naltrexone concentrations are sustained for ~30 days after IM injection.
Primarily hepatic metabolism (glucuronidation) followed by renal excretion of metabolites. Less than 1% excreted unchanged in urine. Fecal excretion minimal (<5%).
Naltrexol (6-β-naltrexol) and naltrexone: primarily renal (60-70% as metabolites, <5% as unchanged drug); biliary/fecal (minor route, <10%).
Category A/B
Category C
Opioid Antagonist
Opioid Antagonist