pharmacology of pain lecture 3 Flashcards
2 types of opioids
morphine
synthetic analogues
structure of morphine
backbone is phenathrene
3 rings at 90 degrees to the other 2
2 planar rings and 2 aliphatic rings
free hydroxyl groups on benzene ring
what does morphine affect
CNS
gi tract
4 types of receptor
mu
delta
kappa
sigma
Mu receptor what is it responsible for
analgesic action of morphine also respiratory depression euphoria sedation and dependence
delta receptor what is it responsible for
important in periphery
contributes to analgesia
kappa receptor what is it responsible for
it contributes to analgesia
may cause sedation and dysphoria
don’t contribute to dependence
some analgesics are kappa selective
sigma receptor
not true opioid receptor
some opioid cause hallucinations
only certain opioid bind such as pentazocine
effects of opioids on the nociceptive pathway
peripheral action
inhibits discharge of nociceptive afferent
morphine also releases histamine from mast cells
effects of opioids on the nociceptive pathway
in the spinal cord
inhibits neurotransmission in the dorsal horn
iv in spinal cord is very effective
what are opioids attached too
g proteins
what of the g proteins cause when activated
inhibition of adenylate cyclase
decreasing intracellular cAMP
coupled to K+ and Ca2+ which inc or dec their opening
this can inhibit pre synaptic transmission reducing post.
more the 75% are
are presynaptic mu receptors in the dorsal horn
antagonists of opioid receptors
naloxone,
naltrexone
morphine inhibits what in the dorsal horn
inhibits the release of substance p
