Opioid Analgesics 1 Flashcards
What are the general indications for opiates?
- Moderate to severe dental pain - that cannot be managed effectively by NSAIDS
- Those whom NSAIDS are contraindicated
What term is used to describe opiates, their antagonists, and the receptors stimulated by opioid drugs?
Opioids
How can opioids be classified?
- Mechanism of action:
- Agonists, partial agonists, mixed opioids (agonists/antagonists), antagonists
- Chemical structure
- Degree of efficacy that they produce
What are opioids mechanism of action?
- They bind to receptors in both CNS and spinal cord
- Produce altered perception of pain reaction
True or false: opioid receptors that mediate specific pharmacologic effects and adverse reactions are stimulated to varying degrees by individual opioids?
True
Where do opiates have their analgesic effect?
On the descending pain-modulating circuit - where there’s a lot of endogenous opioid peptides
Where do systemic opiates produce analgesia?
At widely distributed sites throughout the CNS
In the pain modulatory system, what neurotransmitter is used?
Serotonin
What activates the descending pathway circuit of pain?
- Noxious stimuli
- Pain
- Pyschological factors (placebo responders)
- Opioids
The analgesia system is mediated by what 3 major componenets, where chemical mechanisms of opioid analgesics will take place?
- Periaquaductal grey matter (midbrain)
- Nucleus raphe magnus (medulla)
- Pain inhibitory neurons (dorsal horns of the spinal cord)
In addition to the opiate receptors - what other kind of receptors or connections are there in the descending pathways?
Noradrenergic and serotonergic receptors
Which projections are Serotonergic? And what are they highly sensitive to?
Projections from the periaqueductal gray matter (PAG) and RVM (rostroventral medulla)
Highly sensitive to morphine
What projections are noradrenergic?
Projections from the dorsolateral pons - application of Norepinephrine to spinal cord blocks noxious stimuli in dorsal horn
What are the 3 groups of endogenous opioids?
- Endophins
- Enkephalins
- Dynorphins
What 3 different receptors do the endogenous opioids act through?
- Mu
- Delta
- Kappa
They are G protein-coupled receptors
Where are the endogenous opioid peptides produced?
In the pituitary gland and the hypothalamus
The endophrins cross-top in the limbic system, what is an indication of this?
When people get emotional when they take opioids
Which endogenous opioid is expressed in cells in the arcuate nucleus of the hypothalamus and in the brainstem, act via mu and influences appetite and sexual behavior?
Beta-endorphins
Which endogenous opioid is widely distributed throughout the brain and acts via mu and delta?
Enkephalins
Which endogenous opioid is found in the spinal cord and in many parts of the brain, including the hypothalamus, acts via kappa?
Dynorphins
What are endorphins derived from and what do they produce?
Derived from precursor molecules and produce opiate-like effects.
Where are endorphins found?
In the gut (pancreatic islet cells), sympathetic nervous system, adrenal medullary chromaffin cells, CNS
MU receptors
Naturally occuring endorphins as well as opioid medications act via the mu receptors found in where?
The gastrointestinal tract - why you can get constipation from opioids (slows down the GI tract)
What are the first isolated compounds on enkephalins?
- Leucine-enkephalin
- Methionine-enkephalin
