Pharma 2: Treatment Of Pain Flashcards
Morphine
Derived from
Administration
Derived from opium (papaver somniferum)
Available orally, IV IM epidural
Endogenous opioid peptides
B-endorphin
Leu-enkephalin
Met-enkephalin
Dynorphin
(natural)
Opioid receptors
U
S
K
Opioid receptor mechanism
G protein coupled; Go/Gi—> inhibit AC
There4 no cAMP no PKA
U agonists
MAIN ANALGESIC OPIOID
Where are opioid receptors located
Nociceptive Primary Afferent Fibers
SC
Supraspinal sites
Periphery
GIT
U agonist
Morphine
Opioid analgesics and u agonists
Morphine
Codeine
Pethidine
Fentanyl
U agonist and SNRI
Tramadol
U agonist NMDA RECEPTOR ANTAGONIST
Methadone (used to treat addicts)
U antagonist with longer duration of action
Naloxone
Naltrexone
Drug of abuse and u agonist
Heroin (diamorphine)
Opioid receptor like (ORL1)
Properties
An orphan receptor ie has no affinity for opioid nor is it bind or gets blocked by NALOXENE
It has a similar amino acid sequence though
Opioid receptor location
70% of m-OR found on central terminals of small-medium diameter PRIMARY AFFERENT FIBERS—> C and Ad fibers which transmit sensations of pain
Ab fibers and opioid receptors
NONE since Ab is for touch sensation
Opioid receptors location in spinal cord
Highest levels are found superficially in Lamina 1 and 2 where the c fibers end
Lower levels (quantities)—> deepest laminae
Supraspinal OR
Reostral ventromedial
Periaqeuductal grey body
Opioid receptors in the cns
Most are presynaptic ie not even in the lamina