Lecture 3 8/27/24

Question 1

What are the main reasons to use opioids?

Answer 1

-mainstay of analgesia
-drug/species dependent sedative effects

Question 2

What are the synergistic effects of opioids when combined with a major sedative?

Answer 2

-more profound sedation
-more profound analgesia

Question 3

What is the mechanism of action for opioids?

Answer 3

binds to mu, kappa, and/or delta opioid receptors, generally resulting in inhibition

Question 4

What are the classifications of opioids based on receptor selectivity?

Answer 4

-pure mu agonist
-partial mu agonist
-mixed agonist/antagonist

Question 5

How does a mixed agonist/antagonist work?

Answer 5

-agonist at the kappa receptor
-antagonist at the mu receptor
-activates kappa receptor to inhibit pain

Question 6

What are the characteristics of pure mu agonists?

Answer 6

-profound analgesia
-moderate sedation

Question 7

Which opioids fall into the pure mu agonist category?

Answer 7

-morphine
-meperidine
-hydromorphone
-oxymorphine
-methadone
-fentanyl
-remifentanil

Question 8

What are the characteristics of partial mu agonists?

Answer 8

-moderate analgesia
-minimal sedation

Question 9

Which opioid is the main drug in the partial mu agonist category?

Answer 9

buprenorphine

Question 10

What are the characteristics of kappa agonists/mu antagonists?

Answer 10

-mild analgesia for visceral pain only
-moderate sedation

Question 11

Which opioid is the main drug in the kappa agonist/mu antagonist category?

Answer 11

butorphanol

Question 12

At which locations do opioids function?

Answer 12

-brain
-spinal cord
-peripheral nociceptors
-joints
-immune cells

Question 13

What are the routes of administration for opioids?

Answer 13

-IV
-IM
-epidural
-oral/transmucosal
-transdermal

Question 14

What are the opioid side effects seen at the CNS level?

Answer 14

-analgesia
-sedation
-dysphoria/possible euphoria
-increased locomotor activity

Question 15

What is the opioid side effect seen at the respiratory level?

Answer 15

dose-dependent respiratory depression

Question 16

Which species must be carefully monitored for resp. depression when using opioids?

Answer 16

primates and rabbits

Question 17

What is the opioid side effect seen at the cardiovascular level?

Answer 17

drug-dependent, vagally mediated bradycardia

Question 18

Which opioid is most associated with bradycardia side effects?

Answer 18

methadone

Question 19

Which drugs are used to treat opioid-induced bradycardia?

Answer 19

-atropine
-glyco

Question 20

What are the opioid side effects seen at the GI level?

Answer 20

-ileus/constipation
-nausea and vomiting

Question 21

How do opioids affect temperature regulation in cats?

Answer 21

all opioids lead to hyperthermia in cats

Question 22

What are the characteristics of opioid-induced histamine release?

Answer 22

-primarily associated with morphine
-seen most commonly with fast IV administration
-can lead to hypotension, tachycardia, and urticaria

Question 23

Which opioids are at greatest risk for diversion/inappropriate use by people?

Answer 23

pure mu agonists, which are schedule II

Question 24

What are the characteristics of morphine?

Answer 24

-duration of action around 2-4 hours
-most common side effects are vomiting and histamine release
-full mu agonist

Question 25

What are the characteristics of meperidine?

Answer 25

-duration of action around 1 hour
-most common side effects are vomiting, histamine release, and anti-cholinergic effects (increased heart rate)
-full mu agonist

Question 26

What are the characteristics of hydromorphone?

Answer 26

-duration of action around 4-6 hours
-most common side effects are panting and vomiting
-full mu agonist

Question 27

What are the characteristics of methadone?

Answer 27

-duration of action around 2-4 hours
-NMDA antagonist/good for wind-up/chronic pain
-most common side effect is profound bradycardia
-full mu agonist

Question 28

What are the characteristics of fentanyl?

Answer 28

-duration of action around 30 minutes
-given as a CRI or transdermal patch to increase duration
-also given oral/transmucosal
-full mu agonist

Question 29

What are the characteristics of remifentanil?

Answer 29

-duration of action around 3-5 minutes
-given as a CRI to increase duration
-metabolized by plasma esterases; safe for the liver
-full mu agonist

Question 30

What are the characteristics of thiafentanil, carfentanil, and etorpine?

Answer 30

-very potent!!
-small volumes used for immobilization of large zoo species
-PPE must be used
-must have reversal agent readily available
-full mu agonists

Question 31

What are the characteristics of buprenorphine?

Answer 31

-partial mu agonist
-duration of action around 6-8 hours
-given oral/transmucosal
-difficult to reverse
-adverse effects are mild

Question 32

What are the characteristics of simbadol?

Answer 32

-concentrated buprenorphine
-duration of action around 24 hours
-licensed for cats
-given SQ

Question 33

What are the characteristics of transdermal buprenorphine?

Answer 33

-licensed for cats
-up to 96 hours of analgesia
-must be applied 2 hours prior to painful stimulus
-less crazy side effects compared to simbadol

Question 34

What are the characteristics of butorphanol?

Answer 34

-mixed kappa agonist and mu antagonist
-duration of action around 1 hour
-mild adverse effects
-kappa agonism causes sedation
-act as reversal agents for full mu agonists

Question 35

What are the characteristics of naloxone?

Answer 35

-opioid antagonist
-duration of action around 20-30 minutes
-may need to be given multiple times for opioids with longer durations of action

Question 36

What are the characteristics of naltrexone/nalmefene?

Answer 36

-opioid antagonists
-longer duration of action
-used in wildlife/zoo species that cannot be monitored closely enough to use naloxone