2.09 Analgesic drugs Flashcards
What class of drugs affects pain at the site of injury by decreasing inflammation?
NSAIDS
What group of drugs block nerve condition?
Local anaesthetics
What 2 groups of drugs modify the transmission of nociceptive signals in the dorsal horn of the spinal cord?
Opioids
antidepressant drugs
What activates or potentiates descending inhibitory controls on pain sensation?
Opioids
Are the following weak or strong opioids? morphine hydromorphone fentanyl heroin
Strong
Are the following weak or strong opioids?
codeine
tramadol
dextropropoxyphene
Weak opioid
What group of drugs do these belong to?
diclofenac
indomethacin
naproxen
NSAID
What are the 3 mechanisms involved in descending tracts and suppression of nociceptive transmission in the dorsal horn?
- Direct presynaptic inhibition of neurotransmitter release
- Direct postsynaptic inhibition
- Indirect inhibition
How does direct presynaptic inhibition of neurotransmitter release on nociceptors work?
There is GPCR activity that suppresses the opening of Voltage activated calcium channels
(calcium is required for exocytosis, so this is dampened)
How does direct postsynaptic inhibition work in nociceptive transmission at the dorsal horn?
There is GPCR mediated K+ channel opening; this hyperpolaises the cell;
more stimulus is required before an action potential is sent
How does indirect inhibition work in nociceptive transmission at the dorsal horne?
Activation of the inhibitory interneurons
-enkephalinergic and GABAergic
suppress transmission of pre and post-synaptic mechanisms.
Which mechanism of dorsal horn nociceptive neurotransmission do opioid drugs mimic?
Indirect inhibition- activation of inhibitory interneurones.
Which 3 sites can opioid receptors be found?
pons/midbrain: periacqueductal grey matter, nucleus raphe magnus
spinal cord
What is the cellular action of opioids?
Opioids bind GPCR coupled opioid receptors.
These are all coupled to Gi or Go.
This causes:
-Inhibition of voltage activated Ca channels (pre-synaptic)
-Opening of K+ channels (post-synaptic)
What are mu opioid receptors responsible for?
analgesic action
se: respiratory depression, constipation, euphoria, sedation, dependence
