Premedication- Opioids And Muscle Relaxants

Question 1

What are the strongest available systemic analgesics?

Answer 1

Opioids!

• best choice for treatment of acute pain!

Question 2

T/F: The benefits of using opioids during anesthesia is that you can decrease the dose of anesthetics and they cause minimal CV side effects

Answer 2

True

Question 3

Which opioid is a mixed agonist-antagonist ?

Answer 3

Butorphanol

Antagonist on mu and agonist on kappa

Question 4

Is butorphanol a good choice for strong pain?

Answer 4

NOPE

Can up-regulate pain because of antagonistic effect

Question 5

Potency tells you the _______ and efficacy tells you the _________ of the effect

Answer 5

Dose; strength

Eg fentanyl is more potent than hydromorphone, therefore less dose is needed for the same effect

Question 6

What drug is a partial mu agonist.

Answer 6

Buprenorphine

Question 7

T/F: under appropriate conditions, a partial agonist may act as an antagonist of a full agonist

Answer 7

True

Question 8

What effects do opioids have on CNS?

Answer 8

Analgesia!!
- great for acute pain, not so much for chronic

Decrease MAC
-species dependent (may increase the MAC in horses)

Question 9

T/F: sedation by opioids is stronger if there is pain

Answer 9

True

Question 10

What is the MOA of opioids to induce or inhibit vomiting?

Answer 10

Outside BBB- stimulate chemoreceptor trigger zone —> simulate vomiting

Inside BBB- inhibit vomiting center

Question 11

Do lipid or water soluble opioids cause more vomiting?

Answer 11

Water soluble (eg morphine) - enter the brain slowly, therefore work more on CTZ peripherally to induce vomiting

Question 12

What effects do opioids have on the CV system?

Answer 12

No direct effects!
-suitable for most risk patients

May indirectly decrease HR and BP be reducing sympathetic tone and increasing parasympathetic tone

Question 13

What effects do opioids have on the respiratory system?

Answer 13

Depress

However healthy animals can tolerate high doses well

Question 14

Opioids cause myosis in _______ and mydriasis in _______

Answer 14

Dog; cat

Question 15

What are the effects of opioids on the GI ?

Answer 15

Dedication
Obstipation
Spasm of the sphincter of Oddi (hepato-pancreatic sphincter)

Question 16

Normally opioids cause hypothermia, but post-op we are concerned about hyperthermia in what species?

Answer 16

Cats

Question 17

When are opioids indicated?

Answer 17

Premedication!
-alone or combo with benzodiazepines/ ketamine/acepromazine/a2 agonists

Perioperative analgesia

Treatment of acute and chronic pain

Question 18

What is the onset and duration of morphine?

Answer 18

Slow onset 30-40min

Long duration 4-6hrs

Question 19

Morphine is metabolized in the liver to??

Answer 19

Active metabolite

Question 20

Why may hydromorphone/oxymorphone be preferred to morphine in dogs?

Answer 20

Morphine may cause histamine release, especially after high doses

Question 21

T/F: morphine is used for epidural analgesia

Answer 21

True

-duration 12-24hrs

Question 22

What is the MOA of mathadone?

Answer 22

Full u agonist

NMDA antagonist

Question 23

T/F: fentanyl has a long onset and duration of action

Answer 23

False

Onset 15-20min

Question 24

Remifentanil has similar potency to fentanyl, but has what property that makes it more ideal for CRI?

Answer 24

Does not accumulate

Fentanyl accumulator after long infusions

Question 25

What is a weak and short acting opioid analgesic that can worsen strong pain sensation, and may antagonize ful u agonists ?

Answer 25

Butorphanol

Question 26

What opioid has a stronger effect than butorphanol but weaker than morphine?

Answer 26

Buprenorphine (partial u agonist)

Question 27

Why do we prefer Buprenorphine in cats rather than full u agonists?

Answer 27

Cause less excitation | Can be given in oral mucosa

Question 28

What is the onset and duration of action of Buprenorphine ?

Answer 28

Onset 20-40min Duration 6-8hrs

Question 29

How is tramadol administered?

Answer 29

PO

Question 30

What is the MOA of tramadol

Answer 30

Inhibit NE and serotonin repudiate | -> metabolized in liver -> metabolite is a U opioid agonist

Question 31

What are the opioid antagonists?

Answer 31

Naloxone | Naltrexone

Question 32

What opioid antagonist is long acting and reveres long acting opioids like carfentanyl in wild animals

Answer 32

Naltrexone

Question 33

What centrally acting muscle relaxant is used in large animal anesthesia?

Answer 33

Guaifenesin

Question 34

Can guaifenesin be used as a sole agent for pre-medication ?

Answer 34

Nope | -no analgesia or unconsciousness

Question 35

T/F: Guaifenesin is a muscle relaxant, therefore we should be concerned about significant impacts on cardiovascular and respiration

Answer 35

False Has minimal effect on CV and respiratory system

Question 36

What is the most common concentration used for guaifenesin?

Answer 36

5% GG in dextrose

Question 37

What are complications if a >10% concentration of Guaifenesin is used?

Answer 37

Thrombophlebitis, hemolysis

Question 38

What is the onset of effect of Guaifenesin?

Answer 38

Very short !! Onset 2min Duration 10-20min

Question 39

What is the use of guaifenesin

Answer 39

Premedication | Part of triple drip - GG+ a2 agonsit + ketamine