Alpha 2 agonists

Question 1

What pathways do alpha-2 agonists affect?

Answer 1

perception, modulation, and transmission.

Question 2

Why is sedation so effective with alpha 2 agonists?

Answer 2

because of a decrease in norepi release

Question 3

What is the competitive antagonist for dexmedetomidine?

Answer 3

atipamezole

Question 4

What is the competitive antagonist for xylazene?

Answer 4

yohimbine

Question 5

What are the sedative and analgesic effects of alpha 2 agonists?

Answer 5

they have competitive agonism for alpha-2 receptors in the sensory cortex of the brain, causing sedation. The alpha 2 receptors in the spinal cord cause analgesia and muscle relaxation.

Question 6

What are the autonomic nervous system effects of alpha 2 agonists?

Answer 6

cause vasoconstriction

Question 7

Which is the most specific alpha 2 agonist?

Answer 7

dexmedetomidine

Question 8

Which is the least specific alpha 2 agonist?

Answer 8

xylazine

Question 9

What are the most common routes of administration of alpha 2 agonists?

Answer 9

IV or IM.

Question 10

T/F: alpha 2 agonists don’t cross the BBB

Answer 10

False.

Question 11

What is the emetic of choice for use in cats?

Answer 11

xylazine

Question 12

T/F: the cardiovascular effects of alpha 2 agonists are bi-phasic.

Answer 12

True.

Question 13

What is phase I when using alpha 2 agonists likely to cause?

Answer 13

peripheral vasoconstriction, which will increase systemic vascular resistance and cause a transient increase in mean arterial blood pressure, causing reflex bradycardia. The heart rate will drop to maintain constant cerebral perfusion pressure.

Question 14

What receptors mediate phase I?

Answer 14

alpha 1 receptors

Question 15

What receptors mediate phase II? What is the result of phase 2?

Answer 15

alpha 2 receptors mediate it. There is peripheral vasodilation, decrease in norepi, and the heart rate stays low. Can lead to hypotension and bradycardia.

Question 16

By what percentage can cardiac output decrease with alpha 2 agonists?

Answer 16

30-50%

Question 17

When should you treat decreased heart rate and what do you do to treat it?

Answer 17

Treat when the patient becomes cardiovascularly unstable. You can reverse or give an anti-cholinergic if the P is in sx.

Question 18

What is the most common bradyarrhythmia to occur with alpha 2 agonists?

Answer 18

second degree incomplete AV block

Question 19

What causes decreased cardiac output when using alpha 2 agonists?

Answer 19

increase BP and reflex bradycardia.

Question 20

What effect do alpha 2 agonists have on the respiratory system?

Answer 20

decrease in resp rate and mild resp. depression. In sheep, goats, and horses you will see an increase resp. rate, airway pressures, and pulmonary resistance. These changes can lead to hypoxemia or pulmonary edema.

Question 21

Do alpha 2 agonists have a diuretic effect?

Answer 21

Yes. they reduce ADH release and its function.

Question 22

In what animals may these drugs cause abortion in?

Answer 22

In ruminants, due to myometrial contractions.

Question 23

What are the clinical uses of alpha 2 agonists?

Answer 23

sedation (dose dependent, NOT anesthesia), pre-anesthetic, analgesia**, emetic, behavioral, and chemical ejaculation in horses.
**=important

Question 24

What 2 drugs should you not use with alpha 2 agonists?

Answer 24

epinephrine and atropine.

Question 25

When are alpha 2 agonists contraindicated?

Answer 25

in critically ill patients and patients with shock.

Question 26

How should the reversal agents for alpha 2 agonists be administered?

Answer 26

IM. Administering it IV can cause cardiovascular collapse.

Question 27

Will alpha-2 antagonists reverse both sedative and analgesic effects?

Answer 27

Yes.