Comparative Pharmacology
Head-to-head clinical analysis: NALTREXONE versus VIVITROL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: NALTREXONE versus VIVITROL.
NALTREXONE vs VIVITROL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Naltrexone is a pure opioid antagonist that competitively binds to μ-opioid receptors, blocking the effects of endogenous and exogenous opioids. It also antagonizes κ- and δ-opioid receptors to a lesser extent.
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.
Oral: 50 mg once daily for opioid dependence; 25 mg initially for first dose to minimize adverse effects. Intramuscular: 380 mg every 4 weeks for alcohol dependence.
380 mg intramuscularly every 4 weeks, alternating gluteal injections.
None Documented
None Documented
Clinical Note
moderateMethylnaltrexone + Fesoterodine
"The serum concentration of the active metabolites of Fesoterodine can be increased when Fesoterodine is used in combination with Methylnaltrexone."
Clinical Note
moderateNaltrexone + Methadone
"The therapeutic efficacy of Methadone can be decreased when used in combination with Naltrexone."
Clinical Note
moderateNaltrexone + Dabigatran etexilate
"The serum concentration of the active metabolites of Dabigatran etexilate can be increased when Dabigatran etexilate is used in combination with Naltrexone."
Clinical Note
moderateNaltrexone: 3.9–10.3 hours; active metabolite 6β-naltrexol: 12.9 hours. Context: Trough levels of 6β-naltrexol sustain receptor blockade for 24–48 h.
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 renal (60% as metabolites, including 6β-naltrexol; <2% unchanged) and biliary/fecal (30%).
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
Naltrexone + Sufentanil
"The therapeutic efficacy of Sufentanil can be decreased when used in combination with Naltrexone."