Antiemetics

Question 1

Activation of vomit center

Answer 1

Direct - upsetting sights/smells/pain. Direct from sensor organs, fear or anticipation
Indirect - activations of chemoreceptor trigger zone by either stomach/small intestine sending signals or drugs (anticancer/opioids, ipecac) activating CTZ

Question 2

Receptors involved in emetic response

Answer 2

Serotonin, glucocorticoids, substance P, neurokinin, dopamine, acetylcholine, histamine

Question 3

Ondansetron

Answer 3

Serotonin receptor antagonist (5-HT3) in the chemoreceptor trigger zone (CTZ) and afferent vagal neurons in upper GI tract.
Even more effective combined with dex

Question 4

Glucocorticoids as antiemetics

Answer 4

Methylprednisolone (solumedrol) and dex. Mechanism unknown

Question 5

Aprepitant

Answer 5

Substance P/neurokinin1 antagonist. Prolonged duration of action, but should be combined with other drugs (good with dex or zofran)
Inhibitor and inducer of CYP3A4 so has complicated drug reactions

Question 6

Benzos for antiemetics

Answer 6

Lorazepam in combo for CINV (chemotherapy induced). Helps sedate, suppress emesis and anterograde amnesia. Also good for EPS from other antiemetics like phenothiazine

Question 7

Dopamine antagonists

Answer 7

Sides of EPS, antichol effects, hypotension and sedation

Promethazine (phenergan) - resp depression and local tissue injury

Question 8

Butyrophenones for antiemetic

Answer 8

Haloperidol and droperidol (inapsine)

Also block D2 receptors in CTZ

Question 9

Metoclopramide

Answer 9

Reglan

Blocks dope receptors in CTZ

Question 10

Cisplantin

Answer 10

Chemo drug with max N/V 48-72 hours after

Question 11

Hyperemisis gravidum

Answer 11

Hypokalemia, dehydration, 5% loss of body weight, ketonuria

Doxylamine plus B6 (pyridoxine) is effective without negative fetal outcomes

Question 12

Scopolamine

Answer 12

Muscarinic antagonist
Blocks neuronal pathway from inner ear to vomit center
Dry mouth, blurred vision, drowsiness, urinary retention, constipation, disorientation

Question 13

Antihistamines for motion sickness

Answer 13

Dimenhydrinate which block receptors for acteylcholine and histamine which both contribute to antiemetic effects

Question 14

Two main ways CTZ activated

Answer 14

Signals from stomach and small intestine

Direct action of chemicals

Question 15

Receptors involved in vomiting

Answer 15

Serotonin (5HT3)
Glucocorticoids
Substance P
Neurokinin
Dopamine
Histamine
ACH

Question 16

Serotonin receptor antagonists

Answer 16

Zofran, best for chemotherapy, radiation, anesthesia, viral gastritis, preggo

Question 17

Zofran MOA

Answer 17

Blocks 5ht3 serotonin receptors in CTZ and upper GI

Question 18

Zofran adverse

Answer 18

Headache, dizzy, Diarrhea, GI, QT prolongation
4mg IV
8mg IM
Peds 0.1mg/kg SIVP max 4mg

Question 19

Metoclopramide

Answer 19

Blocks dopamine/serotonin receptors in CTZ, also increases upper GI motility by enhancing Ach
Good for post operative procedures, also good for chemo/opioids/toxins

Question 20

Metoclopramide interactions and adverse

Answer 20

EPS, sedation, diarrhea
Antipsychos and MAOIs may interact
Contras are bowel obstruction/perforation/bleeding, EPS, seizures, hypersens

Question 21

Metoclopramide dose

Answer 21

10mg IV in 50mL over 15 minutes or 10 IM for migraine
For nausea over 5 minutes or 10mg IM still
No repeats