Opioids Flashcards
How many Canadians report pain (both acute and chronic)?
More than 40% of Canadians report poorly managed pain
What is the definition of pain?
An unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage
What are the four G-protein coupled opioid receptors found in the human body?
- Mu
- Kappa
- Delta
- Nociceptin
How do opioid receptors modify perception of pain?
These receptors are Gi or Go coupled proteins.
When an agonist binds to these proteins, cAMP decreases and Inwardly rectifying K+ channels are inhibited
“Calms down pain signals”
Where are the opiod receptors located?
Peripheral, spinal, and brain receptors
What are some examples of endogenous opiods?
- Enkephalin
- Dynorphin
- Substance P
- Endorphin
What are some characteristics of endogenous opioids?
They are short peptide molecules
Need to undergo some post-translational modifications and metabolic activity to become active
Released from synaptic vesicles
What is the biggest source country of pharmaceutical grade exogenous opioids?
Tasmania, an Australian state
Which opioids undergo both Phase I and II metabolism?
- Codeine (Morphine–>Morphine-6-glucoronide)
- Hydrocodone (Hydromorphone–>Hydromorphone-6-glucoronide or Norhydrocodone)
- Oxycodone (Oxymorphone–>Inactive metabolites or Noroxycodone)
What opioids undergo Phase II metabolism only?
Morphine (Morphine-6-glucoronide)
What opioids undergo Phase I metabolism only?
- Fentanyl (Norfentanyl)
- Methadone (inactive metabolites
- Tramadol (O-desmethyltramadol)
In general, how does Acetaminophen impart an analgesic effect?
It is a CNS-selective cyclooxygenase inhibitor
Anandamide reuptake inhibitor (boost endocannabinoid levels)
In general, how do NSAIDs impart an analgesic effect?
- They are COX inhibitors (and subsequently inhibit prostaglandins, which are mediators of pain, inflammation, and fever
In general, how do cannabinoids impart an analgesic effect?
Activate CB1 (a G-protein coupled receptor involved in neurotransmission)
Once CB1 is activated by a cannibinoid, it inhibits release of neurotransmitter
What distinguishes endogenous opioids from exogenous opioid drugs?
Endogenous opioids are peptides