Pre-medicant Drugs

Question 1

How do alpha-2-agonists work?

Answer 1

Drugs that bind alpha 2 receptors in the brain and spinal cord
Block transmission of nociceptive impulses
Exact mechanism not fully mechanism

Question 2

What are examples of alpha-2-agonists?

Answer 2

Medetomide

Dexmedetomidine

Question 3

What are advantages of alpha-2-agonists

Answer 3

Duration and level of sedation, dose dependant
Profound drug sparing effect
Provides muscle relaxation
Provides analgesia

Question 4

What are disadvantages of alpha-2-agonists?

Answer 4

Profound effects on CVS
Caution in patients with cardiovascular disease, liver disease or vomiting patients
Dries bronchial secretions

Question 5

How do phenothiazines work?

Answer 5

Dopamine receptor antagonists

Question 6

What are examples of phenothiazines?

Answer 6

Acetylpromazine (ACP)

Question 7

What are the advantages of ACP?

Answer 7

Tranquilise/ sedation - increasing dose can lead to longer sedation rather than deeper
Long duration action - up to 6hrs
Smooth recovery
Relatively safe for CVS - protective against arrhythmias
Relatively safe for respiratory system 0 at standard doses
Anti-emetic
Smooth muscle relaxation
Mild anti-histamine effect

Question 8

What are disadvantages of ACP?

Answer 8

Causes vasodilation and will lead to hypotension
May cause hypothermia 
Decreased seizure threshold 
Slow to reach peak effect
Long duration 
No analgesia 
Unpredictable effects

Question 9

When should ACP be used with care?

Answer 9

in the hypo-volameic, dehydrated, large and epileptic

Question 10

How do benzodiazepines work?

Answer 10

Work by enhancing the neurotransmitter GABA

Question 11

What are examples of benzodiazepines?

Answer 11

Diazepam

Midazolam

Question 12

What are advantages of benzodiazepines?

Answer 12

Safe
Minimal effects on CVS and respiratory system
Good muscle relaxation
anti-epileptic action

Question 13

What are disadvantages of benzodiazepines?

Answer 13

can have unpredicatable action
not sufficient premed when used alone in healthy animals
diazepam is painful when given by I/m injection

Question 14

How do anti-muscarinic work?

Answer 14

Decrease parasympathetic tone by blocking transmission via acetyl choline .
They also antagonise the parasympathetic nervous system

Question 15

What are examples of anti-muscarinic?

Answer 15

Atropine

Glycopyrrolate

Question 16

What are advantages of anti-muscarinic?

Answer 16

Reduces salivation and bronchial secretion
Counteracts bradycardia where there is vagal stimulation likely
Counteracts bradycardia in patients with high vagal tone
Helps prevent ‘vagal events’ during reversal of muscle relaxants

Question 17

What are disadvantages of anti-muscarinic?

Answer 17

Can cause increased HR and metabolic rate
May cause arrhythmias
Thickens bronchial secretions
Gastrointestinal ileus
Pupil dilation can lead to visual disturbance

Question 18

How do opioids work?

Answer 18

Act by combining with specific receptors in the brain and spinal cord.
Decrease the transmission of noxious stimuli

Question 19

What are examples of opioids?

Answer 19

Full agonists - morphine, pethidine, fentanyl, methadone
Partial Agonists - buprenorphine.
Antagonists - naloxone

Question 20

What are advantages of opioids?

Answer 20

Provide analgesia, euphoria and sedation
Little effect om respiration at correct dose
Little effect on CVS
Drug sparing effect
Pain relief provided may improve ventilation in cases of thoracic wall injury

Question 21

What are disadvantages of opioids?

Answer 21

High doses lead to profound respiratory depression 
Contraindicated in animals with ICP
Vomitting may occur due to morphine 
Constipation 
Anti-tussive effect 
Urinary retention if given spinally