Β-Naltrexamine
β-Naltrexamine, or 6β-naltrexamine, is an opioid receptor antagonist related to naltrexol and naltrexone. It has served as a parent pharmacophore for irreversible antagonists of the μ-opioid receptor such as β-chlornaltrexamine and β-funaltrexamine. Naltrexamine itself is a neutral antagonist of the MOR and the δ-opioid receptor with similarly high affinity for both receptors.