title: Classification of opioid receptors.
mesh_terms: D000700:Analgesics / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D001665:Binding Sites; D006168:Guinea Pigs; D008024:Ligands; D051379:Mice; D011869:Radioligand Assay; D051381:Rats; D011957:Receptors, Opioid / Q000032:analysis* / Q000187:drug effects / Q000378:metabolism
chemical_list: D000700:Analgesics; D008024:Ligands; D011957:Receptors, Opioid