Sedation and premedication

Question 1

Name a phenothiazine used as a sedative …

Answer 1

Acepromazine

Question 2

Name a NMDA antagonist…

Answer 2

Ketamine

Question 3

What effects can phenothiazines have on the cardiovascular system?

Answer 3

Hypotension due to vasodilation, Syncope due to hypotension (high vagal tone) and bradycardia, Adrenaline reversal potentiating vasodilation, anti-arrhythmia, reduced PCVNA

Question 4

What effects do Phenothiazines have on the respiratory system?

Answer 4

Decrease sensitivity to CO2, paired with a decrease in respiratory rate, potentiate the respiratory depressant effect of other drugs

Question 5

How can Phenothiazines act as anti-emetics?

Answer 5

They inhibit dopamine activity in the CTZ

Question 6

How can sedative drugs cause hypothermia?

Answer 6

Due to vasodilation and decreased activity in the thermoregulatory centre

Question 7

Does ACP have analgesic effects?

Answer 7

No

Question 8

What is the onset and offset of ACP?

Answer 8

Onset - 30 mins, Offset - 4-8 hrs

Question 9

Name four receptors which are acted upon by Phenothiazines.

Answer 9

Dopamine, adrenergic (a1), cholinergic, histamine

Question 10

Does ACP cause muscle relaxation in patients? What potential problems does this cause?

Answer 10

Yes, causes muscle relaxation around the pharynx (particularly problematic in brachycephalics)

Question 11

Name three alpha-2 agonists commonly used in practice…

Answer 11

Medetomidine, xylazine, romifidine, detomidine

Question 12

Do alpha-2 agonists have analgesic effects?

Answer 12

Yes

Question 13

How are a2As dealt with in the body?

Answer 13

Metabolised in the Liver and excreted in the urine.

Question 14

What cardiovascular effects are observed with a2A administration?

Answer 14

Initial arterial hypertension with resulting peripheral vasoconstriction. Reflex bradycardia occurs(vagal and sympatholytic). Eventually BP is reduced to just below normal.

Question 15

How do a2As cause diuresis?

Answer 15

Decreased ADH secretion, reduced renin secretion (RAAS), aids urethral relaxation

Question 16

What respiratory effects can a2As have on patients?

Answer 16

Reduced RR, increased TV. Overall minute ventilation does not change.

Question 17

a2As act as muscle relaxants. What effect can this have in the body?

Answer 17

Increased risk of gastro-oesophageal reflux (reduced LOS tone). Mydriasis and reduced aqueous tumour production.

Question 18

Atipamezole can act as a reversal for which class of sedatives? What side effects may occur?

Answer 18

a2As - tachycardia, muscle tremors, over alertness, panting, vomiting.

Question 19

Which Benzodiazepines are liscenced for use in veterinary practice?

Answer 19

None though diazepam and midazolam are commonly used

Question 20

What is the mechanism of action of Benzodiazepines?

Answer 20

They act upon bdz receptors associated with GABAa receptors. They increase GABA affinity of these receptors (in inhibitory neurotransmitter)

Question 21

Does Ketamine act as a muscle relaxant?

Answer 21

No, it increases muscle tone.

Question 22

Does Ketamine have analgesic effects?

Answer 22

Yes