Wed 1 opioid analgesics Flashcards
Descending pain pathways inhibit transmission of signal through what order of neurons?
1st and 2nd
Opiate vs opioid
opiate: drug derived from opium poppy
opioid: generic term; all substances, endogenous and exogenous, that bind opioid receptors
Mu vs Kappa opioid receptors
effects
endogenous opioids that react here
BOTH: decreased GI motility, analgesia
Mu: Resp. depression, physical dependance
Endorphins, Endomorphins
Kappa: Sedation
Dynorphins
What types of proteins are Mu and kappa? How do opioids work on channels in the ascending pain pathway?
G-protein coupled receptors (Mu and Kappa) in the opioid signal transduciton pathway
presynaptic inhibition is the stoppage of Ca channels
postsynaptic inhibition is the activation of K channels
What opioid receptor is on the first order neuron and the second order neuron in the ascending pain pathway? This blocks the release of what neurotransmitter?
Mu
glutamate and substance P
How do opioids work on the descending inhibitory pain pathway?
stop GABA secretion.
opioid —-/ Gaba —-/ main inhibitory pain neuron —-/ pain
Two examples of opioid antagonists
Naloxone - acute overdose - injection - short duration of action
Naltrexone - addiction - oral
Example of a partial opioid agonist
codeine
Two mixed agonist-antagonists
Pentazocine:
- agonist at Kappa
- antagonist at Mu
Buprenorphine:
- Partial Mu agonist, antagonist at all others
- often used with naloxone, an antagonist
Two examples of transdermal opioids
fentanyl, buprenorphine
Action of opioids on:
Cortex
Pain perception, reaction to pain, euphoria, sedation
Action of opioids on:
Medulla
Respiratory depression
Antitussive effects
Nausea, vomiting
Thermoregulation
Action of opioids on:
Spinal cord
Depresses pain reflexes
Stimulates non-pain reflexes
Action of opioids on:
eye, occulomotor nerve
Miosis (pinpoint pupils) – little tolerance so good indicator of opioid use
Action of opioids on:
Vagus nerve
Bradycardia
Increased GI tone
