Selective naltrexone-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 kappa opioid receptor antagonist, norBNI, and delta 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 kappa and delta opioid receptors in a variety of pharmacologic, physiologic, and biochemical effects.