Naltrexone is:-
Mu receptor agonist
Delta receptor agonist
Kappa receptor agonist
Mu receptor antagonist
Naloxone, naltrexone and nalmefene are potent mu receptor antagonists with significant blocking action at kappa and delta receptors also. Naloxone is given parenterally (ineffective orally) and is a very sho acting drug. Nalmefene is also given parenterally but has a longer half life. Naltrexone is long acting orally effective opioid antagonist. Naloxegol-Naloxone conjugated to PEG polymer
Opioids and Alcohols