antiemetic

Question 1

what is nausea

Answer 1

unpleasant feeling that often precedes vomiting

Question 2

what is emesis (vomiting)

Answer 2

forcible emptying of gastric, and occasionally intestinal contents

Question 3

what are anti emetic agents

Answer 3

used to relieve N&V
- harder to control nausea

Question 4

vomiting reflex

Answer 4

in brain regions:
- vomiting center (VC): medulla oblongata, coordinated muscles involved in vomiting
- chemoreceptor trigger zone (CTZ): MO, once stimulated leads to vomiting reflex

Question 5

vomiting reflex hypothermia

Answer 5

• histamine (H1 receptors)
• ACh (muscarinic receptors)
• 5-HT (serotonin) (5-HT3 receptors)
• dopamine (DA2 receptors)
• substance P (neurokinin 1 receptors)

Question 6

antiemetic drugs

Answer 6

most drugs are receptor antagonists
- inhibit neurotransmitter action in vomiting reflex

used in many causes of N&V
- cancer chemotherapy induced (CINV)
- postoperative with general anesthesia
- motion sickness

work before N&V start

Question 7

mechanism of action and indications (5-HT antagonists)

Answer 7

• block 5-HT3 (serotonin) receptors in the CTZ/VC and GI
• CINV, post op N&V
• most successful
• ondansetron

Question 8

moa and indications (dopamine antagonists)

Answer 8

• block DA receptors in CTZ
• can be used for other things: antipsychotic and prokinetic (increase GI motility) agents
• good for more severe vomiting (CINV, radiation therapy)
• chlorpromazine (antipsychotic)
• metoclopramide (prokinetic)

Question 9

moa and indications (ACh antagonists)

Answer 9

• block ACh receptors in inner ear and reticular formation
• block transmission of nauseating stimuli to VC
• used for motion sickness
• taken in patch behind ear (PO AE)
• scopolamine

Question 10

moa and indications (antihistamine antagonists)

Answer 10

• block H1 receptors
• prevent cholinergic stimulation in vestibular and reticular areas
• traditional antihistamines
• dimenhydrinate (gravol)

Question 11

antiemetics adverse effects

Answer 11

vary according to drug used:
- ondansetron: dysrhythmia (long Q-T)
- DA antagonists: movement disorders
- scopolamine: anticholinergic effects
- antihistamines: sedation + anticholinergic effects

Question 12

mechanism of action and indications (glucocorticoids)

Answer 12

• unknown mechanism of action as antiemetic
• CINV
• used alone and in combination
• methylprednisolone
• dexamethasone

Question 13

moa and indications (substance P/neurokinin 1 receptor antagonists)

Answer 13

• blocks in CTZ
• prevents post op and CINV
  prolonged duration of action

Question 14

moa and indications (tetrahydrocannabinol THC)

Answer 14

synthetic derivatives of psychoactive substnace in marijuana
- used for N&V associated with chemotherapy
- second line drugs
- nabilon, dronabinol

Question 15

client care

Answer 15

drugs taken prophylactically
- chemotherapy: 30min to 3 hours before
- motion sickness: diminhydrinate 1 hour before travel, scopolamine patch applied 4h before travel