Opioid analgesics

Question 1

definition: opium

Answer 1

exudate from poppy seeds containing 20 biologically active components including morphine and codeine

Question 2

definition: opiate

Answer 2

drug extracted from exudate of the poppy

Question 3

definition: opioid

Answer 3

natural or synthetic drug that binds to opioid receptors producing agonist effects

Question 4

what are the endogenous opioids?

Answer 4

endorphins, enkaphalins, dynorphins

Question 5

what are the endogenous opioid receptors?

Answer 5

mu 1

Question 6

where are the mu 1 receptors located? what is their function?

Answer 6

outside spinal cord

central interpretation of pain - supraspinal analgesia

Question 7

where are the mu 2 receptors located? what is their function?

Answer 7

throughout CNS - brainstem and spinal cord

supraspinal and spinal analgesia 
respiratory depression 
constipation 
physical dependence 
euphoria

Question 8

what are the metabolites of morphine?

Answer 8

morphine-6-glucoronide (M6G) and M3G

Question 9

how is morphine metabolized?

Answer 9

glucoronidation

Question 10

heroin and codeine are metabolized to what compound?

Answer 10

morphine

Question 11

what GPCRs are associated with opioid binding?

Answer 11

Gi / Go

Question 12

what is the mechanism of opioid binding to Gi / Go receptors?

Answer 12

inhibition of adenylyl cyclase - decreased cAMP
loss of intracellular calcium and decreased release of NTs
increase postsynaptic opening of potassium - hyperpolarization

Question 13

what is the mechanism of analgesia for opioids in the ascending pain pathways?

Answer 13

inhibition of afferent pain transmission
peripheral effects
dorsal horn - presynaptic blocking of pain mediating NTs and postsynaptic activation of secondary afferent neurons via increased potassium

Question 14

opioids have what effect on NTs in the spinal cord? what is the result?

Answer 14

opioids activate GABA neurons in spinal cord

reduced activation of secondary afferent neurons

Question 15

what is the mechanism of analgesia for opioids in the DESCENDING pain pathways?

Answer 15

blockage of inhibitory GABAergic interneurons

Question 16

what are the sites of action for opioids in the descending pain pathways?

Answer 16

periaqueductal gray - midbrain
rostral ventral medulla - brainstem
locus coeruleus - pons

Question 17

what occurs as a result of increased pCO2 following opioid-induced respiratory depression? what is the clinical significance?

Answer 17

reflexive cerebral dilation

contraindication in head trauma

Question 18

what is the mechanism for opioid-induced cough suppression?

Answer 18

via brainstem chemoreceptor trigger zone (area postrema)

Question 19

what are the CV effects of opioids?

Answer 19

hypotension and bradycardia

Question 20

which drug class should be avoided in combination with opioid use? which opioid specifically should be avoided? why?

Answer 20

MAOI

meperidine

hyperpyrexic reaction including hypertension

Question 21

what are the opioid antagonists? what is their clinical use?

Answer 21

naloxone, naltrexone

opioid overdose

Question 22

what are the cough suppressant opioid agents?

Answer 22

codeine, dextromethorphan

Question 23

what is the role of diphenoxylate?

Answer 23

antidiarrheal

Question 24

what is the role of loperimide?

Answer 24

antidiarrheal

Question 25

morphine is an agonist at which receptors?

Answer 25

mu, kappa, delta

Question 26

hydromorphone is how many times more potent than morphine?

Answer 26

7-10x

Question 27

which opioid antagonist is the primary overdose agent that can reverse CNS and respiratory depression within 30 seconds?

Answer 27

naloxone (IV)

Question 28

which opioid antagonist is the primary maintenance drug in the treatment of addiction?

Answer 28

naltrexone

Question 29

how do opioids affect the reward pathway?

Answer 29

modify action of DA in nucleus accumbens and central/ventral tegmental areas

Question 30

what is the leading cause of opiate dependence and abuse?

Answer 30

euphoria

Question 31

what agent is the primary pharmacologic intervention used to treat opioid addiction? what is the strategy?

Answer 31

methadone tapering effect