Chapter 10 - Opioids Flashcards
What are opiods?
a class of psychoactive substances that acy on opioid receptors in the CNS and other parts of the body; produces euphoria (highly abused)
Opioids are called ____ and are used for ____
pain relief (also used to treat diarrhea and as a cough suppressant)
Opioid death in Canada
major drugs of abuse and causes of many accidental overdose; today fentanyl is the main concern; ~20 deaths a day;
Opioids are derived from ____
papaver somniferum (sap of the poppy is raw opium)
Three naturally occurring opiates (from opium)
Morphine, codeine, thebaine
Morphine can be further processed into ____
Heroine
(Heroine = morphine + acetic anhydride)
Five semisynthetic opioids
Diacetylmorphine (heroine), desomorphine (krokodil), buprenorphind, hydrocodone, oxycodone
Two fully synthetic opioids
Fentanyl, methadone
-not derived from naturally occurring opioids
History of opium use
Used for 1000s of years; sold in drug stores in 19th century
Absorption (pharmacokinetic properties)
Oral administration (codéine, méthadone); IV injection (heroine; most common for illicit use); inhalation (used to be smoked)
Distribution (pharmacokinetic properties)
readily cross BB ; differ in speed (ex heroine crosses faster than morphine, produces greater high, more potent, 4-8x more addictive)
Metabolism (pharmacokinetic properties)
Occurs in the liver; active metabolites with similar psychoactive properties are common
Elimination (pharmacokinetic properties)
Rates vary from drug to drug
- methadone and buprenophine and long elimination rates (not as potent)
What is the endogenous opioid system?
Comprised of several NT and receptors; NTs consist of β- endorphin, met-enkephalin, leu-enkephalin, dynorphin A, dynorphin B, and neoendorphin (they are neuropeptides that are cleaved from larger propeptide molecules)
What is proopiomelanocortin?
source of β-endorphin
what is proenkephalin
the source of met- and leu- enkephalin
what is prodynorphine
the source of dynorphin A, dynorphin B, and neoendorphin
endogenous opioids bind to what 3 types of opioid receptors?
µ (pronounced “mu”)
Δ (“delta”)
κ (“kappa”)
most opioids act on the ____ receptor
µ
-opioids are classified by the effects on the receptor
pure opioid receptor agonists are ____ and ____
fentanyl and morphone
partial opioid receptor agonists
lower efficacy for activating receptors than full agonists
-buprenorphine
pure opioid receptor antagonists
block receptors; used to treat opioid addiction or emergency antidote
-naloxone and naltrexone
2 ways opioids increase dopamine release in nucleus accumbens
- inhibiting GABA neurons in the VTA that synapse on DA neurons (leads to disinhibition of DA neurons therefor incr DA in the mesolimbic projection)
- inhibiting GABA neurons in the NA that project to the VTA (also leads to disinhibition.. same as prev)
2 ways opioids affect the pain system
2 pathways affecting nociception
1. Pain information is carried by Aδ and C fibers through the dorsal horn of the spinal cord and release glutamate and substance P at synapses with spinothalamic neurons.
2. Spinothalamic neurons send nociceptive information to the thalamus which routes the information to somatosensory cortex, the cingulate cortex, and the amygdala
