There are various ways of describing what is opioid. The common feature of all the drugs belonging to the group of these drugs is a phenanthrene ring with side chain and additional rings that might be added to the central ring itself or to the side chains.
1. Naturally occurring: morphine, codeine, kheline, noscapine, and thebaine.
2. Semi-synthetic: Diacetylmorphine (diamorphine, heroin), hydrocodeine, oxymorphone
3. Synthetic: Further sub classified under opioid as
a) Phenyl piperidines: Meperidine (Pethidine), phenoperidine and fentanyl and its congeners
b) Morphinans: Levorphanol, butarphanol
c) Benzomorphans: Pentazocine, phenazocine
d) Diphenyl compounds: Methadone
e) N-allyl compounds: At 17 position, i.e., at tertiary amine; if an allyl group is attached to the N-, then resultant compounds completely change their entire spectrum and get converted as antagonists, as described by what is Opioid .
One example is the following
N-allyl normorphine (Nallorphine), n-allyl oxomorphine (Naloxone). In all the compounds, the changes at the N-allyl position convert them into an antagonist. For example: n-allyl cyclobutyl methyl butarphanol (Nalbuphine)
It becomes absolutely imperative that the relevance of all these drugs in correlation with their receptors be taken into consideration.
Logically the second opioid emerges on the basis of the clinical activity in association with receptor binding.
This was in brief about what is Opioid?
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