Morphine opioid receptor binding

Wahlstrom, A., Lenhammar, L., Ask, B., Rane, A. Tricyclic antidepressants inhibit opioid receptor binding in human brain and hepatic morphine glucuronidation. Pharmacol. Toxicol. 75(1), 23-27, 1994. 

Opioid receptor binding Alfentanil is a (j-selective opioid (Cookson et al., 1983) with a receptor affinity in the range of morphine and fentanyl. 

Opioid receptor binding Codeine has a low affinity at j-, 5-, and K-opioid receptors and the in vivo effects are predominantly induced by morphine, formed by metabolic O-demethylation. 

Opioid receptor binding Dextromoramide is a p-selective opioid with a higher receptor affinity than morphine. 

Opioid receptor binding Dextropropoxyphene has a lower p-opioid receptor binding capacity than morphine. Binding at other opioid receptors is even weaker. 

Opioid receptor binding Dezocine (Chen et al., 1993) is a mixed agonist-antagonist with binding affinity to the p-receptor in the range of morphine. The 5- and K-affinity is 10-100-fold lower (O Brien and Benfield, 1989). 

Opioid receptor binding Diamorphine (Inturrisi et al., 1983) has a 10-100fold lower p-opioid receptor binding affinity than morphine. The relevant opioid properties originate from the high p-receptor affinity of the metabolites 6-acetylmorphine and morphine (Umans and Inturrisi, 1981). 

Opioid receptor binding Ethylmorphine is an ethyl congener of codeine and has a low opioid receptor affinity (Chen et al., 1991). Like codeine, it is metabolized to the active principle morphine. 

Opioid receptor binding Fentanyl is a p-selective potent opioid with a similar receptor binding affinity to morphine. The higher in vivo potency results from its greater lipophilicity (Subramanian, 2000). 

Opioid receptor binding Hydromorphone has a high affinity and selectivity for the p-opioid receptor, the p-affinity is about 10-fold higher than that of morphine. 

Opioid receptor binding Levomethadone is the more potent and p-selective levo-enantiomer of racemic methadone (Sim, 1973). It has an opioid receptor affinity in the range of morphine. 

Opioid receptor binding Morphine has a high (nanomolar) binding affinity for the opioid receptor. The affinity for the 6- and k- receptor is at least 10-fold lower. 

Opioid receptor binding Piritramide is a synthetic p-opioid with morphine-like affinity and receptor selectivity. 

Chen, J.C., Smith, E.R., Cahill, M., Cohen, R., Fishman, J.B. The opioid receptor binding of dezocine, morphine, fentanyl, butorphanol and nalbuphine. Life Sci. 1993, 52, 389-396. 

Christensen, C.B. The opioid receptor binding profiles of ketobemidone and morphine, Pharmacol. Toxicol. 1993, 73, 344-345. 

Dynorphin may also influence nociception at the spinal level. The levels of prodynorphin mRNA and immunoreactive dynorphin increase in the chronic inflammatory arthritic model (158). Dynorphin also inhibits morphine or P-endorphin-induced analgesia in naive animals and enhances analgesia in tolerant animals, indicating that this peptide may have a regulatory role in opioid analgesia (159). This effect does not appear to be mediated by a classical opioid receptor, since des-tyrosine dynorphin, which does not bind to opioid receptors, also antagonizes morphine analgesia (160). 

Bond C, LaForge KS, Tian M, et al Single-nucleotide polymorphism in the human mu opioid receptor gene alters beta-endorphin binding and activity possible implications for opiate addiction. Proc Natl Acad Sci U S A 95 9608-9613, 1998 Borron SW, Monier C, Risede P, et al Flunitrazepam variably alters morphine, bu-prenorphine, and methadone lethality in the rat. Hum Exp Toxicol 21 399-603, 2002... 

Morphine and its derivatives continue to be considered the gold standard for alleviating pain. Morphine is metabolized in the liver via N-dealkylation and glu-coronidation at the third (M3G) or sixth position (M6G). Although M3G are the most common metabolites (accounts for 50% of the metabolites produced), they elicit no biological activity when bound to MOR. It is the M6G metabolite (accounts for 10% of the metabohtes produced) that elicits the nociceptive/analgesic effect upon binding to the p opioid receptor (Dahan et al. 2008). M6G is predominately eliminated via renal excretion. 

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