id	author	title	date	pages	extension	mime	words	sentences	flesch	summary	cache	txt
cord-017499-51yy7y9n	Freye, Enno	Mechanism of Action of Opioids and Clinical Effects	2008		.txt	text/plain	24955	1278	45	Thus, -selective opioids like morphine, fentanyl and sufentanil, due to the high density of binding sites, mediate their main action within the brain stem and the midbrain. This sterospecificity of opiate action supports the concept of selective receptor binding to a site, which is able to distinguish in "handedness or goodness of fit" of an opioid molecule maximal response induced by administration of the active agent. On the other hand mixed agonist/antagonists, such as pentazocine, nalorphine, levallorphan, nalbuphine and butorphanol, demonstrate characteristics, which enable them to displace a pure agonist at the receptor site (antagonistic effect), but at the same time when administered by themselves, they induce opioid related effects such as analgesia and respiratory depression (agonistic effects; Table II-7) . However, a less potent opioid like codeine or tramadol, even when given in dosages higher than their therapeutic margin, will not induce a clinically relevant respiratory depressive effect ( Figure II-34) .	./cache/cord-017499-51yy7y9n.txt	./txt/cord-017499-51yy7y9n.txt