Antiemetics

Question 1

Which types of drugs are are anti emetic?

Answer 1

Histamine receptor antagonists
Serotonin receptor antagonists 
Muscarinic receptor antagonists 
Dopamine receptor antagonists
Cannabinoids
Neurokinin 1 antagonists
Corticosteroids and dexamethasone

Question 2

What is emesis?

Answer 2

The act or instance of vomiting

Question 3

What is an antiemetic?

Answer 3

An agent that prevents vomiting

Question 4

Where is emesis controlled and centralised?

Answer 4

Within the brainstem in a neural network on the dorsal surface of the medulla oblongata.

Question 5

What regulates the vomiting reflex?

Answer 5

CNS

Question 6

What are the 3 major inputs to the dorsal vagal complex which cause nausea and vomiting?

Answer 6

1 - chemoreceptor trigger zone (toxins, drugs)
2 - vagal pathway (sensory input (pain smell sight), stimuli from pharynx and GI tract)
3 - vestibular pathway (disorienting motion)

Question 7

Where is the main site of action of antiemetic drugs?

Answer 7

Chemoreceptor trigger zone

Question 8

What are Cyclizine, Cinnarizine and Promethazine? What do they treat? Side effects?

Answer 8

Histamine 1 antagonists/antihistamines that treat motion sickness & morning sickness. Side effects of drowsiness and sedation

Question 9

What is Betahistamine hydrochloride? How does it work? What does it treat? Side effects?

Answer 9

Histamine 3 agonist that treats vertigo. Works b activating H3 receptors on blood vessels in the inner ear to cause local vasodilation and increased permeability. Side effects of GI disturbances, headaches, rashes and pruritus

Question 10

What are Hyoscine and Scopolaimine? What do they treat? Side effects?

Answer 10

Muscarinic receptor antagonists that treat motion sickness. Side effects of dry mouth and blurred vision

Question 11

What are phenothiazines (perphenazine, prochloropromazine, metoclopramide and domperidone)? What do they treat? Side effects?

Answer 11

Dopamine receptor antagonists used to treat severe morning sickness. Side effects of sedation hypotension dystopia and dyskinesia

Question 12

What is ondansetron? What does it treat? Side effects?

Answer 12

Anti emetic serotonin receptor antagonist used to treat CINV and PONV. Side effects of GI disturbances and headache

Question 13

What is Aprepitant? What does it treat? Side effects?

Answer 13

Neurokinin 1 antagonist that treats CINV and PONV. Side effects of fatigue constipation diarrhoea loss of appetite ringing in ears and hiccups

Question 14

How do Cannabinoids work? e.g. nabilone

Answer 14

Act as agonists of cannabin receptors

Question 15

Name 3 Emetics used to induce vomiting

Answer 15

Ipecac, apomorphine and activated charcoal