Talk:Morphinan

You have missed out the ether bridge between carbon atoms 4 and 5 - this is neccesary for opioid like actions. I refuse to beleive that methylamphetamine acts in the same way or has similar structures to opioids. Opioids act at defined receptors - mu delta and kappa, producing a cascade of chemical actions in the cell - methamphetamine acts to block the dopamine re-uptake protein at the synapse - thus concentrating dopamine (and to some extent nor-adrenaline) in the synapse - in addition, it encourages the sysnthesis of more dopamine in the pre-synaptic nerve end, but dexamphetamine is better at this than methaphetamine

No, the 4,5-epoxy bridge is not necessary for opioid activity -- see levorphanol, for example.--84.163.107.162 01:59, 14 September 2007 (UTC)

That is not correct: the 4,5-epoxy bridge is required for calling the structure morphinans. Morphinans are the simplified structure based on the morphine backbone. The structure shown here is that of a pro-morphinan which lack the 4,5-epoxy bridge. The first pro-morphinan is synthesised in nature by a P450 enzyme called Salutaridine Synthase, and the last pro-morphinan, the tetra-acyclic salutaridinol-7-acetate, is converted to the first pentacyclic morphinan/opiate alkaloid by thebaine synthase 144.32.241.129 (talk) 16:42, 17 October 2025 (UTC)

Um, I think Codeinone and Morphinone should be removed from the list of morphinans since they have an intact E ring and thus aren't morphinans. Aj1976 08:21, 6 November 2007 (UTC)

Why is the 4,5 bridge an epoxy and not just an ether? —Preceding unsigned comment added by 12.147.63.195 (talk) 14:54, 7 February 2011 (UTC)

The first phrase should be "opiate" instead of "opioid". Please change. — Preceding unsigned comment added by 89.204.139.99 (talk) 21:27, 2 March 2014 (UTC)

Misclassification of fentanyl, methadone and loperamide

The Structure section currently lists fentanyl, methadone and loperamide as examples following the description of the morphinan class. This appears chemically incorrect/misleading. Fentanyl is a phenylpiperidine derivative, methadone is a diphenylheptane derivative, and loperamide is a piperidine derivative; these compounds do not possess the morphinan tetracyclic scaffold. By contrast, morphine is explicitly classified as having morphinan as its parent hydride. I suggest removing the sentence or rewriting it to distinguish structurally unrelated opioid classes. (Reference: James A, Williams J. Basic Opioid Pharmacology - An Update. Br J Pain. 2020 May;14(2):115-121. doi: 10.1177/2049463720911986. Epub 2020 Mar 20. PMID: 32537150; PMCID: PMC7265597.) Deniz Altungoz (talk) 14:36, 20 September 2026 (UTC)