Comparative Pharmacology
Head-to-head clinical analysis: NALTREXONE HYDROCHLORIDE versus VIVITROL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NALTREXONE HYDROCHLORIDE versus VIVITROL.
NALTREXONE HYDROCHLORIDE 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, with highest affinity for mu receptors. Also acts as an antagonist at the toll-like receptor 4 (TLR4).
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.
50 mg orally once daily for opioid dependence; 25 mg orally once daily for alcohol dependence, may increase to 50 mg after one week.
380 mg intramuscularly every 4 weeks, alternating gluteal injections.
None Documented
None Documented
Terminal elimination half-life: ~4 hours for naltrexone; its major active metabolite, 6-β-naltrexol, has a half-life of ~13 hours. The longer half-life of the metabolite contributes to sustained receptor blockade.
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.
Renal: primarily as unchanged drug (<2%) and metabolites (mainly 6-β-naltrexol, glucuronide conjugates); approximately 60% of dose excreted in urine (including metabolites) and about 30% in feces via biliary excretion.
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