Emetics and anti-emetics

Question 1

What are the 2 main drugs used to induce emesis in small animals?

Answer 1

Xylazine and apomorphine

Question 2

What is the mechanism of action of xylazine?

Answer 2

a2-adrenoceptor agonist, binds to receptors in CTZ

Question 3

How is xylazine administered?

Answer 3

I.V. or I.M.

Question 4

What is the main use of xylazine?

Answer 4

Emetic in cats

Question 5

What are the side effects associated with xylazine?

Answer 5

Sedation

Question 6

What is the mechanism of action of apomorphine?

Answer 6

Dopamine agonist, binds to receptors in CTZ

Question 7

How is apomorphine administered?

Answer 7

Parentrally (tablet can be placed under eye and removed once vomiting begins)

Question 8

What is the main use of apomorphine?

Answer 8

Emetic in dogs

Question 9

What are the side effects associated with apomorphine?

Answer 9

Protracted vomiting, excitement, restlessness

Question 10

In which species should vomiting never be induced?

Answer 10

Horses and rabbits

Question 11

What are the 4 therapeutic options for preventing emesis?

Answer 11

Phenothiazines, metoclopramide, neurokinin antagonists, 5HT3 antagonists

Question 12

What is the mechanism of action of phenothiazines?

Answer 12

D2 antagonist

Question 13

Describe the pharmacokinetics of phenothiazines

Answer 13

• Oral administration
• Well absorbed and distributed
• Excreted by kidneys

Question 14

What are the main uses of pheothiazines?

Answer 14

• Broad spectrum anti-emetic

- Sedative

Question 15

What are the side effects associated with phenothiazines?

Answer 15

Hypotension, bradycardia, sedation

Question 16

What is the mechanism of action of metoclopramide?

Answer 16

D2 antagonist

Question 17

Describe the pharmacokinetics of metoclopramide

Answer 17

• Oral, I.M., subcutaneous or slow I.V. administration
• 1st pass metabolism
• Excreted by kidneys

Question 18

What are the side effects associated with metoclopramide?

Answer 18

Movement disorders and fatigue

Question 19

What are the main uses of metoclopramide?

Answer 19

• Anti-emetic

- Gastric motility disorders

Question 20

What is the mechanism of action of neurokinin antagonists?

Answer 20

Nk-1 receptor antagonist

Question 21

Describe the pharmacokinetics of neurokinin antagonists

Answer 21

• Oral or subcutaneous administration

- Hepatic metabolism

Question 22

What are the main uses of neurokinin antagonists?

Answer 22

Broad specturm anti-emetic

Question 23

Are there any side effects associated with neurokinin antagonists?

Answer 23

Hypersalivation and diarrhoea

Question 24

Describe the mechanism of action of 5HT3 antagonists

Answer 24

5HT3 antagonist

Question 25

What are the main uses of 5HT3 antagonists?

Answer 25

Use if metoclopramide is uneffective

Question 26

Are there any side effects associated with 5HT3 antagonists?

Answer 26

Usually well tolerated with few side effects