Opioids

Question 1

where do opioids come from

Answer 1

opium poppy seed pod juice

Question 2

what 3 main drugs does opium contain

Answer 2

heroin, codeine, morphine

Question 3

what is the difference between opiate and opioid

Answer 3

opiate = any natural component of opium
opioid = any natural or synthetic derivative of opium

Question 4

why do we give opioids as pre-meds

Answer 4

because general anesthetics do not inhibit pain signal generation, so a painful stimulus during a procedure could transmit enough pain signals to the RAS to awaken the patient - giving an opioid prevents pain signal generation

Question 5

where are opioid receptors present

Answer 5

pain pathways and in most other organ systems

Question 6

T/F mammals produce endogenous opioids

Answer 6

T

Question 7

what 5 uses are opioid drugs used for

Answer 7

1) analgesia
2) cough suppression (antitussive)
3) sedation
4) treatment of diarrhea
5) emesis (apomorphine)

Question 8

what are the opioid receptor families that cause:
- immediate analgesia
- dysphoria

Answer 8

immediate analgesia:
- Mu
- Delta
- Kappa

dysphora:
- Sigma

Question 9

what is the mechanism of action of opioids on pre-synaptic receptors

Answer 9

mu, delta, kappa receptors inhibit Ca entry, which inhibits NT release

Question 10

what is the mechanism of action of opioids on post-synaptic receptors

Answer 10

mu receptors open K channels, which causes hyperpolarization and inhibits APs

Question 11

what are the effects of mu opioid receptor stimulation (4)

Answer 11

• intense analgesia
• euphoria
• miosis or mydriasis
• respiratory depression (dose-dependent)

Question 12

what are the effects of delta opioid receptor stimulation (4)

Answer 12

similar to Mu

Question 13

what are the effects of kappa opioid receptor stimulation

Answer 13

• moderate analgesia
• no respiratory depression

Question 14

what are the effects of sigma opioid receptor stimulation

Answer 14

• dysphoria
• hallucinations
• respiratory and vasomotor stimulation

Question 15

what can stimulate sigma receptors

Answer 15

opioids and some non-opioids such as ketamine

Question 16

what are the 3 properties of opioid stimulation (i.e. what are the 3 ways that opioids can act on opioid receptors)

Answer 16

1) full agonist
2) partial agonist/antagonist
3) mixed agonist/antagonist

Question 17

which opioids are full Mu agonists?

Answer 17

• morphine
• codeine
• hydromorphone
• meperidine
• fentanyl

Question 18

how does fentanyl act on opioid receptors (and which ones)

Answer 18

full mu agonist

Question 19

how does butorphenol act on opioid receptors (and which ones)

Answer 19

mu partial agonist/antagonist and kappa agonist

Question 20

T/F if you have a patient that presents with severe pain, you should first give a weaker opioid such as butorphanol and then give a stronger opioid such as fentanyl if pain persists

Answer 20

F; if you do this the butorphanol will block the effects of fentanyl by acting as a partial agonist/antagonist on the mu receptor

Question 21

what two drugs are mu partial agonists/antagonists

Answer 21

butorphanol and buprenorphine

Question 22

what is the difference between buprenorphine and butorphanol

Answer 22

both are mu partial agonists/antagonists, butorphanol is a kappa agonist whereas buprenorphine is a kappa antagonist

Question 23

what are the 5 main analgesic opioids

Answer 23

1) morphine
2) hydromorphone
3) fentanyl
4) butorphanol
5) buprenorphine

Question 24

what is the main anti-diarrheal opioid

Answer 24

loperamide

Question 25

what is the main antitussive opioid

Answer 25

butorphanol

Question 26

what is the main emetic opioid

Answer 26

apomorphine

Question 27

what opioids are used for chemical immobilization

Answer 27

1) etorphine 2) carfentanyl

Question 28

what is the duration of analgesia of hydromorphone

Answer 28

3-6h

Question 29

what is the duration of analgesia of buprenorphine

Answer 29

4-8h

Question 30

what is the analgesic potency of fentanyl relative to morphine

Answer 30

100x

Question 31

are opioids weak acids or weak bases

Answer 31

bases

Question 32

what is the metabolism of opioids

Answer 32

phase I and II metabolism with high first-pass effect

Question 33

T/F codeine has a high analgesic effect in dogs because it gets metabolized to morphine

Answer 33

F

Question 34

In regards to full mu agonists: - sedation is most likely in _________ - excitement is likely in __________

Answer 34

- dogs and primates - most other species

Question 35

high doses of morphine cause what in cats; what drug does not do this

Answer 35

excitement - called sham rage; not seen with hydromorphone

Question 36

what can morphine trigger but not fentanyl or hydromorphone

Answer 36

histamine release -> hypotension

Question 37

death from opioid overdose is due to

Answer 37

respiratory arrest -> due to respiratory depression (mu effect)

Question 38

what do we use to reverse opioid overdose

Answer 38

naloxone

Question 39

what effects to opioids have on the gastrointestinal tract

Answer 39

- increase segmentation but reduce propulsion -> constipation - bile sphincter constriction -> biliary colic - nausea and vomiting

Question 40

what is the effect of opioids on the urogenital system

Answer 40

- increases bladder sphincter and detrusor muscle tone -> urgency to urinate but difficult - slows uterine contractions and inhibits birth reflexes

Question 41

T/F fentanyl can be used as an analgesic + sedative prior to induction

Answer 41

T

Question 42

overdose of fentanyl causes

Answer 42

seizures

Question 43

how is fentanyl commonly administered

Answer 43

patch

Question 44

etorphine is _______ more potent than morphine and carfentanyl is _____ more potent than morphine

Answer 44

4000x; 10,000x

Question 45

what is the reversal agent for carfentanyl and etorphine (M99)

Answer 45

diprenorphine (M50/50)

Question 46

the main beneficial effect of buprenorphine is via stimulation of what receptor

Answer 46

kappa receptor stimulation

Question 47

T/F butorphanol is commonly used for post-op analgesia

Answer 47

T

Question 48

how is buprenorphine administered in cats

Answer 48

IM; transmucosal at home

Question 49

how is buprenorphine absorbed

Answer 49

transmucosally

Question 50

what is the main advantage of buprenorphine

Answer 50

at home administration to animals with chronic pain

Question 51

how is apomorphine given

Answer 51

in the eye

Question 52

how does apomorphine trigger vomiting

Answer 52

dopamine receptors

Question 53

T/F vomiting from apomorphine administration can be stopped by giving naloxone

Answer 53

F

Question 54

how does naloxone work

Answer 54

inhibits mu receptors

Question 55

T/F naloxone can be used to treat circulatory shock

Answer 55

T