Antiemetics

Question 1

What are glucocorticoids mentioned?

Answer 1

Dexamethasone and Methylprednisolone.

Question 2

What is the mechanism of action of Dexamethasone?

Answer 2

May work via inhibition of the nucleus tractus solitarius, serotonin reduction, and prostaglandin synthesis.

Question 3

What are the uses of Dexamethasone?

Answer 3

Multimodal PONV prophylaxis in moderate to high-risk patients. Combination therapy recommended (e.g., 5-HT3 antagonist + dexamethasone for children at moderate/high risk).

Question 4

What is the dosage of Dexamethasone?

Answer 4

4 mg IV after induction.

Question 5

What are the adverse effects of Dexamethasone?

Answer 5

Can increase blood glucose levels.

Question 6

What are the clinical considerations for Dexamethasone if PONV occurs within 6hrs postop?

Answer 6

If PONV occurs within 6 hours post-op, repeat doses of the same prophylactic antiemetic should be avoided.

Question 7

What is the use of Methylprednisolone?

Answer 7

Given for PONV.

Question 8

What is the dosage of Methylprednisolone?

Answer 8

40 mg IV.

Question 9

What is the mechanism of action of Ondansetron?

Answer 9

Blocks 5-HT3 receptors in the chemoreceptor trigger zone and GI tract.

Question 10

What are the uses of Ondansetron?

Answer 10

Most widely used antiemetic; more effective for vomiting than nausea.

Question 11

What is the dosage of Ondansetron?

Answer 11

4 mg IV at the end of the procedure.

Question 12

What is the duration of Ondansetron’s effect?

Answer 12

4-6 hours.

Question 13

What are the adverse effects of Ondansetron?

Answer 13

High doses prolong QT interval.

Question 14

What is the dosage of Granisetron?

Answer 14

Given at the end of surgery.

Question 15

What is the mechanism of action of Palonosetron?

Answer 15

Longer half-life than other 5-HT3 antagonists (44 hours).

Question 16

What are the uses of Palonosetron?

Answer 16

Preferred for PDNV (Post-Discharge Nausea and Vomiting).

Question 17

What are the clinical considerations for Palonosetron?

Answer 17

Efficacy increases when combined with dexamethasone.

Question 18

What is the dosage of Palonosetron?

Answer 18

Given at induction.

Question 19

What is the mechanism of action of NK1 Receptor Antagonists?

Answer 19

Blocks NK1 receptors in the nucleus of the solitary tract (NST), where vagal inputs trigger vomiting.

Question 20

What is the use of Aprepitant?

Answer 20

NK1 Receptor Antagonists, FDA-approved for PONV.

Question 21

What is the use of Rolapitant?

Answer 21

NK1 Receptor Antagonists, Has a long half-life, making it effective for PDNV.

Question 22

What is the mechanism of action of Droperidol?

Answer 22

Blocks dopamine receptors in the CNS.

Question 23

What are the uses of Droperidol?

Answer 23

PONV prophylaxis.

Question 24

What is the dosage of Droperidol?

Answer 24

0.625 – 1.25 mg IV given at the end of surgery.

Question 25

What are the adverse effects of Droperidol?

Answer 25

May cause extrapyramidal side effects; contraindicated in Parkinson’s disease.

Question 26

What is the use of Haloperidol?

Answer 26

Alternative to droperidol.

Question 27

What is the dosage of Haloperidol?

Answer 27

1 – 2 mg IV.

Question 28

What are the adverse effects of Haloperidol?

Answer 28

QT prolongation risk.

Question 29

What is the mechanism of action of Transdermal Scopolamine?

Answer 29

Blocks cholinergic impulses to prevent nausea and vomiting.

Question 30

What are the uses of Transdermal Scopolamine?

Answer 30

Most effective when used with PCA (patient-controlled analgesia) for postoperative pain.

Question 31

What is the dosage of Transdermal Scopolamine?

Answer 31

1.5 mg patch applied behind the ear 4 hours before anesthesia.

Question 32

What is the duration of Transdermal Scopolamine's effect?

Answer 32

3 days.

Question 33

What are the adverse effects of Transdermal Scopolamine?

Answer 33

Sedation, dizziness, dry mouth, blurred vision.

Question 34

What is the mechanism of action of Benzodiazepines (Midazolam)?

Answer 34

Reduces dopamine’s emetic effects and decreases serotonin release.

Question 35

What are the uses of Midazolam?

Answer 35

Sedation near the end of surgery. May help reduce PONV but can prolong recovery.

Question 36

What is the mechanism of action of Metoclopramide?

Answer 36

Weak antiemetic with mild dopamine receptor-blocking effects.

Question 37

What are the uses of Metoclopramide?

Answer 37

PONV prophylaxis.

Question 38

What is the dosage of Metoclopramide?

Answer 38

Doses >20 mg effective.

Question 39

When should Metoclopramide be given?

Answer 39

Given at the end of surgery.

Question 40

What are the adverse effects of Metoclopramide?

Answer 40

Can cause dyskinesia and extrapyramidal effects at high doses. Contraindicated in Parkinson’s disease and bowel obstruction.

Question 41

What are the final notes on PONV prophylaxis?

Answer 41

Multimodal PONV prophylaxis is recommended for moderate/high-risk patients. Combination therapy (e.g., 5-HT3 antagonist + dexamethasone) is preferred. Rescue therapy should differ from the prophylactic drug used. If PONV occurs within 6 hours post-op, do not repeat the same prophylactic antiemetic.