Ondansetron

Question 1

What is the brand/trade name for ondansetron?

Answer 1

• Zofran

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}

Question 2

What is the pharmacologic category/class of ondansetron?

Answer 2

• Antiemetic
• Selective 5-HT₃ receptor antagonist

5-HT = serotonin

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}

Question 3

What is the mechanism of action of ondansetron?

Answer 3

• Competitive antagonism of serotonin peripherally on vagal nerve terminals and centrally in the chemoreceptor trigger zone/vomiting center

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}

Question 4

What is the standard dose of ondansetron for PONV prophylaxis or rescue therapy? When should the prophylactic dose be given?

Answer 4

• 4 mg
• administered ~30 mins before emergence for prophylaxis

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}

Question 5

What is the onset of action for ondansetron?

Answer 5

• ~5 minutes, with peak in 10-30 mins

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}

Question 6

What is the duration of action for ondansetron?

Answer 6

• 3-6 hours

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}

Question 7

What are two important anesthetic considerations when administering ondansetron?

Answer 7

• QTc prolongation with high doses and when administered with other drugs known to cause this
• Risk for serotonin syndrome, especially when administered with other serotonergic drugs (e.g. SSRIs, fentanyl, metoclopramide)

_{Anesthesia Guidebook - Episode 19: Anesthesia Top Drawer Run Down - Part 3
UpToDate - Ondansetron: Drug Information}