GI Pharmacology 2 - Slides 1-15

Question 1

List the indications for anti-emetic drugs

Answer 1

Severe nausea and vomiting
Motion sickness
Post-operative nausea and vomiting
Nausea and vomiting associated with chemotherapy

Question 2

What causes vomiting reflex?

Answer 2

Mediated through the vomiting center in the medulla

Vagus nerve, spinal motor nerves to the abdominal muscles

Question 3

What happens when the vomiting reflex is activated?

Answer 3

Reverse peristalsis of the upper GI tract
Glottis closes, breath is held, esophageal and gastric sphincters relax
Abdominal muscles contract to eject gastric contents

Question 4

What are anti-muscarinic agents used for? What options do we have?

Answer 4

Motion sickness

Scopolamine

Question 5

Side effects of scopolamine?

Answer 5

Dry mouth
Blurred vision
Urinary retention

Question 6

What anti-histamines are used as anti-emetics?

Answer 6

Dimenhydrinate (Dramamine)
Promethazine
They cause sedation, anti-muscarinic side effects

Question 7

What are ondansetron, dolasetron, granisetron?

Answer 7

5-HT3 receptor antagonists

Both CNS and peripheral

Question 8

Indications for ondansetron, dolasetron, granisetron?

Answer 8

Effective in CINV (cisplatin)

Question 9

Adverse effects of ondansetron, dolasetron, granisetron?

Answer 9

Headache, diarrhea, constipation

Question 10

What are the phenothiazines?

Answer 10

Prochlorperazine
Chlorpromazine
Fluphenazine
Haloperidol

Question 11

What is the MOA of the phenothiazines?

Answer 11

D2 receptor antagonists in the CTZ

Question 12

Adverse effects of the phenothiazines?

Answer 12

Dizziness
Fatigue
Seizures
Sedation
Increase prolactin
Neuroleptic malignant syndrome

Question 13

What are the cannabinoids?

Answer 13

Dronabinol
THC, oral formulation
Can be used for CINV when other agents have failed

Question 14

MOA of Dronabinol?

Answer 14

Works via central action on the vomiting center

Question 15

Adverse effects of Dronabinol?

Answer 15

Confusion
Euphoria
Dizziness
Mood changes
Orthostatic hypotension
Increased appetite

Question 16

What is Aprepitant?

Answer 16

Substance P antagonists

It is an antagonist at NK1 substance P receptor

Question 17

What is Aprepitant used for?

Answer 17

Vomiting due to cisplatin in all acute (24 hr) patients and many delayed phase (36-72 hour) patients

Question 18

How does Aprepitant compare to the 5ht antagonists?

Answer 18

5ht antagonists work best against acute phase, Sub P best against delayed phase

Question 19

How is Aprepitant administered?

Answer 19

Given with chemo and on following 2 days

Question 20

What is Metoclopramide?

Answer 20

PROKINETIC DRUG
D2 antagonist, D2 receptors suppressed
Decreased CTZ sensitivity, antiemetic
Works by blocking the presynaptic D2 receptors and increasing ACH release
This increases gastric emptying/upper GI motility/Lower esophageal sphincter tone

Question 21

Indications for Metoclopramide?

Answer 21

Gastroparesis

GERD

Question 22

Adverse effects of Metoclopramide?

Answer 22

Dizziness, fatigue, seizures, sedation

Increases prolactin, can cause neuroleptic malignant syndrome

Question 23

What is Cisapride?

Answer 23

Prokinetic
5HT4 agonist
5HT3 antagonist

Question 24

Indications for Cisapride?

Answer 24

GERD

Gastroparesis not controlled by other treatments

Question 25

Adverse effects of Cisapride?

Answer 25

Cardiac arrhythmias, prolonged QT interval due to CYP3A4 interaction with other drugs (increases cisapride) Headache, N/V, abdominal pain

Question 26

What is erithromycin?

Answer 26

Prokinetic drug | Motilin type actions in upper GI tract, LES

Question 27

Indications for erithromycin?

Answer 27

Diabetic gastroparesis

Question 28

Toxicities with erithromycin?

Answer 28

Cramps Impairs motility Dumping of stomach contents into small bowel (used for bezoars due to Procardia XL)

Question 29

Which agent is used for bezoars due to procardia XL?

Answer 29

Erithromycin

Question 30

What is Lubiprostone?

Answer 30

PGE1 analog used for IBS | It activates Cl channels to increase fluid secretion into the GI tract

Question 31

Indications for Lubiprostone?

Answer 31

Treatment of chronic idiopathic constipation and IBS-constipation LUB = lube = lubes GI tract = less constipation

Question 32

What is Alosetron?

Answer 32

5HT3 antagonist, decreases gastric motility

Question 33

Indications for Alosetron?

Answer 33

Diarrhea predominant IBS in women

Question 34

Cautions with Alosetron?

Answer 34

It was introduced and withdrawn in 2000 due to acute ischemic colitis Reintroduced in 2002 with a black box warning and lower dose/specific education and monitoring conditions Use is very limited, a prescribing program is required, at lower doses

Question 35

Adverse effects of Alosetron?

Answer 35

Constipation, sometimes severe requiring constipation Hypertension Arrhythmias Sleep disorders