Central analgesics Flashcards
What is an opioid?
Any substance, whether endogenous or synthetic, that produces morphine-like effects that are blocked by antagonist such as naloxone.
Name 2 natural opioids.
Morphine & codeine.
Name 5 semi-synthetic opiates.
Hydromorphone, Hydrochodone, oxymorphone, oxycodone, etylmorphine.
Name 3 fully synthetic opioids.
Fentanyl, methadone & tramadol.
Name 4 endogenous opioids.
Endorphins, enkephalins, dynorphins and endomorphins.
Name 4 opioid receptors.
Mu, delta, kappa & NOP.
Explain the mechanism of action of activation opioid receptors.
It promotes opining K+ channels –> hyperpolarization of membrane makes cells less likely to fire action potentials. Inhibits opening of voltage-gated Ca2+ channels. Inhibits adenylyl cyclase - causes MAPK activation, mediate long term adaptive changes occurring in response to prolonged receptor activation.
Which opioid receptor is responsible for the major pharmacological effect of morphine?
Mu receptor.
What are the pharmacological action of mu-opioid receptor activation?
Analgesia, hyperalgesia, euphoria, respiratory depression, nausea, miosis, constipation and histamine release.
What is the mechanism of action of Clonidine?
It is a partial agonist with alpha-2a/alpha-1 selectivity.
Where are alpha 2 receptors located?
On the terminals of sensory C-fibers and post-synaptic on second order neurons.
Name 4 antidepressant drug used for pain relieve.
Amitriptiline, Duloxetine, venlafaxine & Fluoxetine.
What is the mechanism of action of Gabapentanoids?
They bind to the alpha2-delta subunit of voltage-gated calcium channels and reduce calcium influx into nerve terminals.
Where is the alpha2-delta subunit heavily expressed?
In the spinal dorsal horn.
