Antiemetics

Question 1

Molecular Targets of the Vomiting Reflex

Answer 1

Question 2

describe the 2 phases of Chemotherapy Induced Nausea and Vomiting (CINV)

Answer 2

1. Acute phase - universally experienced (within 24 hours)
2. Delayed phase - affects only some patients (days 2-5)

Question 3

Scopolamine is a _____

Answer 3

Scopolamine is a muscarinic antagonist

Question 4

Scopolamine is used for prevention and treatment of _____

is it a 1st line agent for CINV?

Answer 4

Scopolamine is used for prevention and treatment of motion sickness

NOT a 1st line agent for CINV

Question 5

list H₁ antagonists

Answer 5

• Diphenhydramine
• Meclizine
• Cyclizine

Question 6

what do H₁ antagonists act on and used for?

Answer 6

vestibular afferents & brainstem -

motion sickness & postoperative emesis

Question 7

list 5-HT₃ Antagonists

Answer 7

“setron”

Ondan-setron, Grani-setron

Question 8

where are 5-HT₃ receptors found?

Answer 8

Critical sites involved in emesis:

• Vagal afferents
• Solitary tract nucleus
• CTZ
• Area Postrema

Question 9

What is the DOC for prophylaxis against immediate CINV?

Answer 9

“-setron” (5-HT₃ antagonists)

Question 10

5-HT₃ Antagonists are also effective against _____

not effective against ____ and ____

Answer 10

5-HT₃ Antagonists are also effective against hyperemesis gravidarum

not effective against delayed CINV and motion sickness

Question 11

Ondansetron AE

Answer 11

• Torsades de pointes
• Headache
• Constipation
• Serotonin syndrome

Question 12

list NK1 antagonists for Substance P

Answer 12

Aprepitant, Fosaprepitant (parenteral)

Question 13

prophylaxis against delayed CINV

Answer 13

Aprepitant/Fosaprepitant

Question 14

Aprepitant/Fosaprepitant is given orally in combination with ___ and ___

Answer 14

Aprepitant/Fosaprepitant is given orally in combination with dexamethasone and 5-HT3 antagonist

Question 15

___ undergoes extensive CYP3A4 metabolism

affecting the metabolism of ___ and ___

Answer 15

Aprepitant undergoes extensive CYP3A4 metabolism

affecting the metabolism of warfarin and OCPs

Question 16

list D₂ receptor Antagonists at the CTZ

Answer 16

• Prochlorperazine
• Promethazine
• Droperidol

Question 17

D2 receptor antagonists have antihistaminic and anticholinergic properties, effectively treating ____

but not effective in ____

Answer 17

D2 receptor antagonists have antihistaminic and anticholinergic properties, effectively treat​ing motion sickness

but not effective in CINV

Question 18

D₂ antagonists have a potential for adverse _____

Answer 18

D₂ antagonists have a potential for adverse extrapyramidal effects

Question 19

list the benzodiazepines

Answer 19

-zepam, -zolam

Lorazepam, Alprazolam, Diazepam

Question 20

Lorazepam, Alprazolam, Diazepam MOA

Answer 20

activates GABA_A in CNS increasing frequency of Cl^- channel opening

no intrinisic antiemetic effects but reduce anticipatory component of nausea and vomiting d/t sedative, amnesic, and anti-anxiety effects

Question 21

Lorazepam, Alprazolam, Diazepam AEs

Answer 21

CNS depression and dependence

Question 22

describe Dronabinol (Δ-9-tetrahydrocannabinol)

Answer 22

• naturally occurring cannabinoid
• stimulates CB1 receptors in the brainstem

Question 23

CINV prophylactic agent when other anti-emetic medications are not effective

Answer 23

Dronabinol

Question 24

Dronabinol AEs

Answer 24

• Marijuana-like “highs”
• Prominent central sympathomimetic activity
  
  • Palpitations, tachycardia, vasodilation, hypotension
  • conjunctival injection (bloodshot eyes)
• Paranoid reactions/ thinking abnormalities
• Abrupt withdrawal of dronabinol → an abstinence syndrome (irritability, insomnia, and restlessness)
• Great caution prescribing to persons with substance abuse Hx