Selective natrexone-derived opioid receptor antagonists

Progress in opioid research relies heavily on ligands as probes to evaluate selectivity of action. The design of such ligands using naltrexone as a precursor has afforded a number of highly selective antagonists. These include the κ opioid receptor antagonist, norBNI, and δ opioid receptor antagonists, NTI and NTB. The unifying concept in the development of these antagonists was the enhancement of selectivity through simultaneous occupation of two neighboring recognition sites by a single ligand. These selective naltrexone-derived antagonists have been used widely to study the involvement of κ and δ opioid receptors in a variety of pharmacologic, physiologic, and biochemical effects.