Antiemetic Agents

Question 1

Where is the vomiting center in the brain?

Answer 1

lower medulla

Question 2

Which receptors are involved in the chemoreceptor associated N/V?

Answer 2

• D2 (dopamine)
• 5HT3 (serotonin)
• NK1 (neurokinin)

Tx: Ondansetron (Zofran)

Question 3

Which receptors are involved in the Cortex and Thalamus receptors [pain, anxiety, anticipation]?

Answer 3

• GABA
• H1

Tx: Benzodiazepines

Question 4

Which receptors are associated with Vestibular system N/V?

Answer 4

• ACh

- H1

Question 5

Serotonin 5-HT3

Answer 5

Ex. Ondansetron (Zofran)

-Lasts 4-9 hours
-Oral or IV
-Reduce dose in hepatic insufficiency*
-Most effective when given preventatively 30 mins before chemotherapy
-Efficacy enhanced with corticosteroid*
ADE: headache, constipation

Dolasetron - most pronounced QT interval prolongation

Question 6

Substance P/Neurokinin 1 Receptor Antagonist

Answer 6

-Advantage: relief from delayed emesis

Question 7

Antihistaminic- Anticholinergic Agents

Answer 7

Ex. Dimenhydrinate (Dramamine)
or
Diphenhydramine (Benadryl)

Question 8

Which Antihistaminic-Anticholinergic is particularly good for vertigo?

Answer 8

Meclizine (Antivert)

Question 9

Phenothiazines

Answer 9

1. Prochlorperazine (Compazine)

Use: breakthrough N/V from chemo

ADE: prolonged QT, sedation, tardive dyskinesia*

Question 10

Phenothiazines: Chlorpromazine (Thorazine)

Answer 10

Dopaminergic blocker and alpha blocker

so… causes decreased BP. Also can affect body temperature

Question 11

Butyrophenones

Answer 11

1. Haloperidol
2. Droperidol
   - QT prolongation/Torsades de pointes (so, get an EKG beforehand)

Question 12

Benzodiazepines

Answer 12

1. Alprazolam (Xanax)
2. Lorazepam (Ativan)
   - give these before chemo

Question 13

Cannabinoids

Answer 13

1. Dronabinol (Marinol)

- Rx

Question 14

Which antiemetic is first line in pregnancy?

Answer 14

Pyridoxine

-can consider methylprednisolone in addition (but don’t exceed 6 weeks)