Premedication- Opioids And Muscle Relaxants Flashcards

1
Q

What are the strongest available systemic analgesics?

A

Opioids!

  • best choice for treatment of acute pain!
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2
Q

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

A

True

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3
Q

Which opioid is a mixed agonist-antagonist ?

A

Butorphanol

Antagonist on mu and agonist on kappa

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4
Q

Is butorphanol a good choice for strong pain?

A

NOPE

Can up-regulate pain because of antagonistic effect

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5
Q

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

A

Dose; strength

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

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6
Q

What drug is a partial mu agonist.

A

Buprenorphine

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7
Q

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

A

True

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8
Q

What effects do opioids have on CNS?

A

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

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

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9
Q

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

A

True

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10
Q

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

A

Outside BBB- stimulate chemoreceptor trigger zone —> simulate vomiting

Inside BBB- inhibit vomiting center

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11
Q

Do lipid or water soluble opioids cause more vomiting?

A

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

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12
Q

What effects do opioids have on the CV system?

A

No direct effects!
-suitable for most risk patients

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

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13
Q

What effects do opioids have on the respiratory system?

A

Depress

However healthy animals can tolerate high doses well

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14
Q

Opioids cause myosis in _______ and mydriasis in _______

A

Dog; cat

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15
Q

What are the effects of opioids on the GI ?

A

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

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16
Q

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

A

Cats

17
Q

When are opioids indicated?

A

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

Perioperative analgesia

Treatment of acute and chronic pain

18
Q

What is the onset and duration of morphine?

A

Slow onset 30-40min

Long duration 4-6hrs

19
Q

Morphine is metabolized in the liver to??

A

Active metabolite

20
Q

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

A

Morphine may cause histamine release, especially after high doses

21
Q

T/F: morphine is used for epidural analgesia

A

True

-duration 12-24hrs

22
Q

What is the MOA of mathadone?

A

Full u agonist

NMDA antagonist

23
Q

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

A

False

Onset 15-20min

24
Q

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

A

Does not accumulate

Fentanyl accumulator after long infusions

25
Q

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

A

Butorphanol

26
Q

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

A

Buprenorphine (partial u agonist)

27
Q

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

A

Cause less excitation

Can be given in oral mucosa

28
Q

What is the onset and duration of action of Buprenorphine ?

A

Onset 20-40min

Duration 6-8hrs

29
Q

How is tramadol administered?

A

PO

30
Q

What is the MOA of tramadol

A

Inhibit NE and serotonin repudiate

-> metabolized in liver -> metabolite is a U opioid agonist

31
Q

What are the opioid antagonists?

A

Naloxone

Naltrexone

32
Q

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

A

Naltrexone

33
Q

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

A

Guaifenesin

34
Q

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

A

Nope

-no analgesia or unconsciousness

35
Q

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

A

False

Has minimal effect on CV and respiratory system

36
Q

What is the most common concentration used for guaifenesin?

A

5% GG in dextrose

37
Q

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

A

Thrombophlebitis, hemolysis

38
Q

What is the onset of effect of Guaifenesin?

A

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

39
Q

What is the use of guaifenesin

A

Premedication

Part of triple drip - GG+ a2 agonsit + ketamine