Premedication Drugs Flashcards Preview

Anesthesiology > Premedication Drugs > Flashcards

Flashcards in Premedication Drugs Deck (89)
Loading flashcards...
1

Purposes of premedication

1. Sedation, analgesia
2. Anesthetic sparing effect
3. Reduction of stress and catecholamine release
4. Redution of O2 demand
5. Increased safety for animals and staff
6. Decrease parasympathetic tone

2

Drugs classes used in premedication

1. Anticholinergics
2. Alpha 2 agonists
3. Phenothiazines and butyrophenones
4. Benzodiazepines
5. Opioids
6. Antihistamines and antibiotics

3

MOA Anticholinergics

Inhibit parasympathetic nervous system
Antagonize muscarinic acetylcholine receptors

4

Anticholinergic drugs

Atropine and glycopyrrolate

5

Atropine

Lipid soluble
Absorbed well IM/SC/PO
Crosses BBB and placenta

Dose: 0.01-0.04 mg/kg IV

6

Glycopyrrolate

Water soluble
Absorbed slowly IM/SC/PO
Does not cross BBB and placenta

Slower than atropine, half the dosage

7

Indications for Anticholinergics

Need for increasing the heart rate (opioid induced or reflex bradycardia)
Need for decreasing salivation and bronchial secretions

8

Contraindications for Anticholinergics

-Tachycardia
-Hyperthyroidism
-Most heart diseases
-Narrow angle glaucoma

9

Cardiovascular side effects of Anticholinergics

1. Second degree AV block (bradycardia and cardiac arrect)
2. Tachycardia
3. Hypertension

10

What part of the heart do Anticholinergics effect?

SA node particularly
AV node is weakly effected

11

Medetomidine/Atropine disadvantages

Vasoconstriction, tachycardia, hypertension

12

Other effects of anticholinergics

1. Relaxes lower esophageal sphincter
2. Mydriasis
3. Bronchodilation
4. Dries airway secretions
5. intestinal paralysis
6. CNS toxicity

13

What drug treats anticholinergic CNS toxicity?

Physostigmine

14

Which Anticholinergic is preferred in rabbits?

Glycopyrrolate

Atropine is broken down too quickly

15

Which class has the strongest available sedative ability?

Alpha-2 Agonists

16

Do Alpha-2 agonists have specific antagonists?

Yes

17

MOA: Alpha-2 agonists

Competitive agonist of alpha-2 receptor (suppress NE release)

18

Location of alpha-2 receptors

1. CNS presynaptic membrane
2. Postsynaptic membrane
3. Extra-synaptic sites

19

Alpha-2 agonist presynaptic effects

1. Sedation
2. Analgesia
3. Reduction of sympathetic outflow from brain
4. Reduction of stress response

20

Alpha-2 agonist postsynaptic effects

Vasoconstriction of arteries and veins

21

Alpha-2 agonist extra synaptic effects

1. Inhibition of lipolysis
2. Inhibition of insulin release- hyperglycemia
3. Natural ligand with Epinepherine
4. Interaction with stress response

22

Alpha-2 agonist CNS effects

1. Species specific sedative (weak in pigs)
2. Some analgesia- synergism with opioids
3. Muscle relaxation

23

Alpha-2 agonist Cardiovascular effects

1. Strong vasoconstriction- high SVR and BP
2. Reflex bradycardia- low CO and tissue perfusion
3. May develop hypotension

24

Should alpha-2 agonists be used with atropine?

No- reflex bradycardia does not need to be treated

25

Alpha-2 agonist Respiratory effects

1. Mild respiratory depression (decreased RR)
2. Increase in tidal volume
3. Increased upper airway resistance
4. V/Q mismatch in horses and ruminants- decreased PaO2
5. Bronchoconstriction, lung edema, and hypoxemia in Ruminants

26

Which alpha-2 agonist is contraindicated in sheep?

Xylazine

27

Alpha-2 agonist GI effects

1. Decreased salivation
2. Decreased lower esophageal sphincter tone
3. Decreased GI motility
4. May induce vomiting- esp cats

28

Xylazine side effect in cattle

Uterine contractions and abortion

29

Alpha-2 agonist indications

1. Sedation of aggressive animmals
2. Sedation in the ICU
3. Sedation to manage post-op airway obstruction
3. Prevention/tx of seizures

30

Alpha-2 agonist contraindications

1. Too young or too old
2. Hemodynamic instability
3. Severely debilitated patient
4. Not suitable for most at risk patients