opioids Flashcards
Morphine
Phenanthrene alkaloids-
Codeine
Phenanthrene derivative- metabolized to morphine
Opiate
Natural
mu receptors
endorphins –>enkephalins–>dynorphins
delta
enkephalins—>endorphins —dynorphins
kappa
Dynorphine —>endorphins—>enkephalins
Opioid receptors are
GPCRs
We have natural ligands that activate our
mu receptors (in CNS and GI system)
Until 1990s, these receptors were known as
orphan receptors —we weren’t able to identify molecules that activated them. Molecules identified were fatty molecules :
Molecule that was discovered which activated the orphan receptors
Andamamide
Endogenous opioid peptides
endorphins and enkefalin— “Runners High”
Most of these opioids are well absorbed, but they undergo
First pass effect –these drugs may be better absorbed –IV. IM TD
Morphine is metabolized to
M3G (90%-excitatory/ euphoric) and M6G (10% analgesia)
Heroin is metabolized to
6-monoacetylmorphine (6-MAM is looked for in the urine) and morphine . Heroin is esterified morphine
How do opioids work?
Opioid receptors are on both the pre syn and post sun – opioids will activate both.
Pre syn- associated with voltage calcium channels.
Post syn-associated with voltage gated potassium channels.
If ligand binds to post syn=efflux of potassium
If ligand binds to pre syn=blocks calcium channels
The receptors are in the brain and spinal cord.
