Antiemesis

Question 1

vomiting center is

Answer 1

the medulla oblongata

Question 2

the vestibular apparatus has which receptors

Answer 2

H1 and muscarinic receptors

Question 3

what is CTZ

Answer 3

The CTZ evolved so that toxic substances could be removed from the body.

Question 4

what’s on the CTZ

Answer 4

The serotonin type 3 (5-HT3), neurokinin 1 (NK1), dopamine 2 (D2), and muscarinic 1 (M1) receptors have all been identified on the CTZ.

Question 5

What is Ménière’s disease?

Answer 5

Vestibular disorders (i.e. Ménière’s disease) are sort of like motion sickness but they’re due to damage to the vestibular apparatus that leads to similar types of problems

Question 6

use for severe morning sickness

Answer 6

vitamin B6, doxylamine

Question 7

morning sickness drug known to cause birth defects

Answer 7

thalidomide

Question 8

drug for chemotherapy with the worst history of emesis

Answer 8

cisplatin

Question 9

drugs to use while a patient is on cisplatin to prevent the risk of emesis

Answer 9

Palonosetron, aprepitant, dexamethasone

Question 10

drugs good at preventing acute phase and delayed phase of vomiting

Answer 10

palonosetron and aprepitant

Question 11

Palonosetron

Answer 11

• It is a 5-HT3 receptor antagonist
• Peripheral in the gut, Central in CTZ and NTS
• Long Half life: Delayed phase emesis
• Eliminated in Urine
• treatment of chemotherapy, radiation-induced and post-operative nausea and vomiting
• it has little to no effect in delayed nausea and vomiting of post-operative

Question 12

Aprepitant

Answer 12

• NK1 receptor antagonist
• central action on NTS and vomiting center
• approved for delayed nausea and vomiting of highly emetogenic treatments
• Potent inhibitiors of CYP3A4
• must decrease the dose of dexamethasone by 50%

Question 13

moderate to high risk of emesis in chemotherapy drugs

Answer 13

cyclophosphamide, anthracyclines, dacarbazine, nitrogen mustard

Question 14

low risk and very low risk of emesis in chemotherapy drugs

Answer 14

palcitaxel, etoposide, bleomycin, methotrexate, vinca alkaloids

Question 15

D2 dopamine receptor antagonists

Answer 15

metoclopramide, phenothiazines

Question 16

D2 antagonists are for

Answer 16

motion sickness

post operative emesis

Question 17

risks include movement disorders and so you avoid them in treating emesis.

Answer 17

phenothiazines; antipsychotics

Question 18

H1 histamine receptor antagonist

Answer 18

diphenhydramine, meclizine, doxylamine

Question 19

diphenhydramine

Answer 19

motion sickness

Question 20

meclizine

Answer 20

motion sickness, vestibular disturbances

Question 21

doxylamine

Answer 21

pregnancy-associated vomiting

Question 22

scopalamine

Answer 22

-transdermally
you do not want to give this drug systemically because you can get blurred vision, dry mouth, but can be used for motion sickness

Question 23

tetrahydrocannabinol agonists

Answer 23

• dronabinol is pretty much a pot pill, used against chemotherapy induced emesis
• also used for glaucoma
• risks associated with medical marijuana and synthetic

Question 24

a. Bulk-forming laxatives

Answer 24

Methylcellulose and psyllium (Metamucil) are common OTC laxatives that are bulk-forming

Question 25

b. There are a group of stool surfactant agents that act as laxatives

Answer 25

i. Docusate is an OTC stool surfactant agent. It can also be given in the hospital to treat post-operative constipation.
ii. Glycerin and mineral oil are stool surfactant agents but they should not be used because of leakage

Question 26

c. Osmotic laxatives

Answer 26

1. GoLytely is an osmotic laxative but it has a bad taste and you need to drink 4 liters of it before a colonoscopy.
2. So in an effort to make osmotic laxatives more palatable, they were able to reduce the volume of GoLytely by half. This was called HalfLytely and you only have to drink 2 liters before a colonoscopy. Also, HalfLytely has proportionately more water than the other ingredients.
3. Osmotic laxatives include magnesium hydroxide, magnesium citrate, and sodium phosphate.

Question 27

d. Stimulant laxatives

Answer 27

are avoided because they’re irritating to the bowel and they have complications. They promote peristalsis so that bowel contents are removed. Senna, aloe, and cascara are naturally occurring stimulant laxatives

Question 28

i. Opioid agonists

Answer 28

include loperamide and diphenoxylate which inhibit peristalsis in the GI tract to prevent diarrhea. Diphenoxylate is sold OTC in combination with atropine (antimuscarinic) as Lomotil. The atropine can interfere with peristalsis as well but it’s really there to prevent people from abusing the opioid.

Question 29

ii. The biggest issue with opioid agonists

Answer 29

is they can sometimes get into the CNS to cause dependence. Usually they don’t get into the CNS however

Question 30

b. Colloidal bismuth compounds

Answer 30

include bismuth subsalicylate (Pepto-Bismol). Pepto-Bismol has two actions.

Question 31

Colloidal bismuth compounds mechanism

Answer 31

i. It interferes with loss of material from the bowel so that diarrhea is prevented.
ii. Bismuth subsalicylate also helps to coat the stomach and so people sometimes use it to treat an upper GI irritation. So Pepto-Bismol can be used to reduce heartburn although it has no effect on stomach acid itself