Antiemetics - Ondansetron (Zofran)

Question 1

Where is the primary vomiting center located in the brain?

A) Cerebellum

B) Nucleus tractus solitarius (medulla)

C) Thalamus

D) Hypothalamus

Answer 1

B) Nucleus tractus solitarius (medulla)

Question 2

Which of the following areas provide sensory input to the vomiting center? (Select 3)

A) Chemoreceptor trigger zone

B) Gastrointestinal (GI) tract

C) Vestibular system

D) Prefrontal cortex

Answer 2

A) Chemoreceptor trigger zone,
B) Gastrointestinal (GI) tract,
C) Vestibular system

Question 3

What is the standard intravenous (IV) dose of Ondansetron for treating nausea and vomiting?

A) 2 mg IV

B) 4 mg IV

C) 8 mg IV

D) 16 mg IV

Answer 3

B) 4 mg IV

TxWes Reference
Dose: 4mg
Onset: 10 min
Duration: 4-9 hr

Question 4

What is the oral dose range of Ondansetron for treating nausea and vomiting?

A) 2-4 mg PO

B) 4-8 mg PO

C) 8-16 mg PO

D) 16-24 mg PO

Answer 4

C) 8-16 mg PO

Question 5

For treating pruritus resulting from neuraxial morphine, what is the recommended IV dose of Ondansetron?

A) 2 mg IV

B) 4 mg IV

C) 8 mg IV

D) 16 mg IV

Answer 5

C) 8 mg IV

Question 6

What is the maximum dose of Ondansetron recommended for patients with liver disease?

A) 4 mg IV

B) 8 mg IV

C) 16 mg IV

D) 24 mg IV

Answer 6

B) 8 mg IV

Question 7

What is the concentration of Ondansetron solution for intravenous administration?

A) 1 mg/mL

B) 2 mg/mL

C) 4 mg/mL

D) 8 mg/mL

Answer 7

B) 2 mg/mL

Question 8

What is the primary mechanism of action of Ondansetron (Zofran)?

A) Dopamine receptor antagonist

B) 5-HT3 serotonin receptor antagonist

C) Histamine H1 receptor antagonist

D) GABA receptor agonist

Answer 8

B) 5-HT3 serotonin receptor antagonist

Question 9

Ondansetron works by blocking serotonin receptors in which of the following locations? (Select 2)

A) Central chemoreceptor trigger zone (CTZ)

B) Peripheral gastrointestinal tract

C) Vestibular system

D) Central nervous system (CNS)

Answer 9

A) Central chemoreceptor trigger zone (CTZ)
B) Peripheral gastrointestinal tract

Question 10

Which statement accurately describes Ondansetron’s central action?

A) Ondansetron acts centrally by blocking dopamine receptors in the brain.

B) Ondansetron acts centrally at the chemoreceptor trigger zone (CTZ) without causing significant neurological effects.

C) Ondansetron causes notable neurological side effects such as dizziness and confusion.

D) Ondansetron has central effects but primarily targets peripheral serotonin receptors.

Answer 10

B) Ondansetron acts centrally at the chemoreceptor trigger zone (CTZ) without causing significant neurological effects.

Question 11

What is the primary ligand for Ondansetron (Zofran)?

A) Dopamine

B) Norepinephrine

C) Serotonin

D) Acetylcholine

Answer 11

C) Serotonin

Question 12

Serotonin’s highest concentration in the body is found in which two primary locations?

A) Liver and Kidneys

B) Brain and Gastrointestinal tract

C) Lungs and Heart

D) Colon and Stomach

Answer 12

B) Brain and Gastrointestinal tract

Question 13

Which type of nausea is Ondansetron (Zofran) not effective against?

A) Chemotherapy-induced nausea

B) Motion sickness / vestibular stimulation

C) Postoperative nausea

D) Nausea from radiation therapy

Answer 13

B) Motion sickness / vestibular stimulation

Question 14

Which organs have detectable levels of serotonin, but are not the primary sites of its highest concentration? (Select 3)

A) Liver

B) Kidneys

C) Brain

D) Colon

Answer 14

A) Liver
B) Kidneys
D) Colon

Question 15

What is the onset time for Ondansetron (Zofran)?

A) Delayed

B) Rapid

C) Slow

D) Variable

Answer 15

B) Rapid

Tx Wes Reference:
10 min

Question 16

What is the approximate half-life of Ondansetron (Zofran)?

A) 1 hour

B) 2 hours

C) 4 hours

D) 8 hours

Answer 16

Answer: C) 4 hours

*Kane Preop Meds: give towards end of case bc don’t want PONV after when pt’s awake
Dose: 4-8 mg IV
*

Question 17

What is the typical duration of action for Ondansetron (Zofran)?

A) 2-4 hours

B) 4-6 hours

C) 6-12 hours

D) 12-24 hours

Answer 17

C) 6-12 hours

TxWes Reference:
4-9hr

Question 18

What is the primary metabolic pathway for Ondansetron (Zofran)?

A) Hydroxylation on the indole ring

B) Methylation of the nitrogen atom

C) Oxidation of the phenyl ring

D) Glucuronidation of the hydroxyl group

Answer 18

A) Hydroxylation on the indole ring

Question 19

After hydroxylation on the indole ring, Ondansetron (Zofran) is further metabolized by which processes?

A) Hydrolysis and methylation

B) Conjugation with glucuronide or sulfate

C) Reduction and oxidation

D) Acetylation and phosphorylation

Answer 19

B) Conjugation with glucuronide or sulfate

Question 20

Ondansetron (Zofran) may have reduced effectiveness in individuals with variations in which enzyme activity?

A) CYP3A4

B) CYP2D6

C) CYP2C19

D) CYP1A2

Answer 20

B) CYP2D6

Question 21

Why should Ondansetron (Zofran) be used with caution in patients with congenital QT prolongation?

A) It may worsen renal function.

B) It can lead to a higher risk of torsades de pointes.

C) It may interact with other antihistamines.

D) It can cause severe gastrointestinal bleeding.

Answer 21

B) It can lead to a higher risk of torsades de pointes.

Question 22

When should Ondansetron (Zofran) be administered in relation to emergence from anesthesia?

A) 5 minutes before emergence

B) 15 minutes before emergence

C) 30 minutes before emergence

D) 1 hour before emergence

Answer 22

C) 30 minutes before emergence

PONV Mordecai Fall 2024

Dolasetron (Anzemet)
Granisetron (Kytril)
Ondansetron (Zofran)
4mg within 15-20 of surgery end; data unclear on 4mg vs. 8mg
Palonosetron (Aloxi) Generally reserved for chemotherapy

Question 23

Which of the following conditions require ECG monitoring when administering Ondansetron (Zofran)? (Select 4)

A) Hypokalemia (hypoK+)

B) Hypercalcemia

C) Hypomagnesemia (hypoMg2+)

D) Congestive heart failure (CHF)

E) Bradyarrhythmias

Answer 23

A) Hypokalemia (hypoK+)
C) Hypomagnesemia (hypoMg2+)
D) Congestive heart failure (CHF)
E) Bradyarrhythmias

or other QT interval prolonging meds

Question 24

Which of the following side effects are commonly associated with Ondansetron (Zofran)? (Select 3)

A) Headache

B) Diarrhea

C) Rash

D) Prolonged QT interval

Answer 24

A) Headache
B) Diarrhea
D) Prolonged QT interval