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pharm II > Alpha 2 agonists and antagonists > Flashcards

Alpha 2 agonists and antagonists Flashcards

1
Q

Name the alpha 2 agonists

A
  1. Dexmedetomidine (Dexdom)
  2. Xylazine
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2
Q

Name the alpha 2 antagonists

A
  1. Atipamezole
  2. Yohimbine
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3
Q

____________ is a mixed A2 agonist/antagonist

A

Medetomidine / Vatinoxan (Zenalpha)

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4
Q

Which parts of the pain pathway do A2 agonists act on?

A
  1. Transmission
  2. Modulation
  3. Perception
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5
Q

Xylazine is approved for use in __________

A

Horse, deer, elk

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6
Q

Dexmedetomidine is approved for us in __________

A

Dogs, cats, exotics

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7
Q

Which species is most sensitive to xylazine?

A

Cows

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8
Q

Why is xylazine not frequently used in small animals?

A

More potent than dexdom, increased morbidity

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9
Q

What is the overall clinical effect of A2 agonists?

A

Sedation and analgesia

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10
Q

Which A2 agonist is more selective to A2?

A

Dexmedetomidine

less A1 effects

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11
Q

How are A2 agonists commonly given?

A

IV or IM

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12
Q

Why are A2 agonists not given SQ?

A

Poor absorption due to local vasoconstriction (some a1 effects)

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13
Q

Which A2 agonist has a longer duration of action?

A

Dexmedetomidine > xylazine

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14
Q

What is the clinical indications for use of xylazine in cats?

A

Emetic of choice for cats to induce vomiting

stimulation of A2 receptors in the emetic center and CRTZ

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15
Q

What occurs in phase I when using A2 agonists?

A

Phase I - Peripheral phase

  • Peripheral vasoconstriction mediated by a1 receptors
  • Causes reflex bradycardia and INC. systemic BP

dont give anticholinergics (Atropine, Glycopyrrolate) during Phase I

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16
Q

What occurs in phase II when using A2 agonists?

A

Phase II - Central phase

  • Decreased sympathetic tone (Dec NE)
  • HR stays low
  • Peripheral vasodilation leading to hypotension and bradycardia

CO can decrease 30-50% with A2 agonists

17
Q

What is the most common arrhythmia seen with A2 agonists?

A

2 degree AV block

18
Q

What does a biphasic effect mean in regards to A2 agonists?

A

Initial vasoconstriction and hypertension followed by vasodilation and hypotension due to CNS depression

19
Q

What might happen to BP if you give atropine for reflex bradycardia?

A

Hypertension and increased afterload (not good)

20
Q

___________ is a specific competitive antagonist for dexmedetomidine

A

Atipamezole (Antisedan)

21
Q

___________ is a specific competitive antagonist for yohimbine

A

Xylazine

22
Q

You want to reverse the effects of an A2 agonist, what route of admin would you give the reversal?

A

IM

More side effects when given IV like CV collapse

23
Q

Effect of A2 agonists on GI motility?

A

Decreases GI motility

Emetic of choice in cats

24
Q

Effects of A2 agonists on the uterus?

A

Stimulates myometrial contractions, risk for abortions

25
Q

Effects of A2 agonists on the kidneys?

A

Mild diuresis (PU) by reducing ADH release

26
Q

What can be high on a biochem panel when using A2 agonists?

A

Glucose (hyperglycemia)

Due to decrease release of insulin

more pronounced in horses and ruminants

be careful using A2 agonists on diabetic patients

27
Q

Which metabolic condition would be a precaution when selecting an A2 agonist?

A

Diabetes

A2 decreases insulin resulting in hyperglycemia

28
Q

A2 agonists can cause _________ (hypothermia/hyperthermia)

A

Hypothermia (low temp) due to vasoconstriction

29
Q

What precaution must be taken when using A2 agonists on deer?

A

Delayed hypersensitivity rxn

30
Q

A2 agonists should not be used concurrently with ____________

A

Epinephrine and atropine

31
Q

__________ is the most selective A2 antagonist

A

Atipamezole (Antisedan)

32
Q

What GI side effects can be seen after administration of Atipamezole?

A

Mild salivation and diarrhea

(A2 antagonist - Reversal agent)

33
Q

What side effects can be seen if an A2 antagonist is given without an A2 agonist?

A

CNS excitement, tachycardia and hypotension due to vasodilation

34
Q

Why might Medetomidine/Vatinoxan (ZenAlpha) be used over other A2 agonists?

A

Faster onset, shorter duration

  • can still be reversed with Atipamezole
  • less CV depression (less hypotension)

good for outpatient procedures

35
Q

Medetomidine/Vatinoxan (ZenAlpha) precautions?

A

Beware of hypotension in cats and horses

36
Q

Other therapeutic uses for A2 agonists?

A

Mitoban toxicity, Amitraz tick collar toxicity

37
Q

A2 agonists can be used in horses for?

A

Chemical ejaculation

pharm II (23 decks)

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