Antiemetics Flashcards Preview

Year 2 Pharmacology > Antiemetics > Flashcards

Flashcards in Antiemetics Deck (15):
1

What anti-metics are used for cancer patients?

Histamine H1-Receptor Antagnists - Cyclizine, Cinnarizine, Promethazine

Histamine H3-Recepor Antagonists - Betahistin, Hydrochlordie

5-HT3 Receptor Antagonists - Ondansetron, Granisettron, Palonosetron

Muscarinic mACh Receptor Antagonists - Hyoscine, Scopolamine

D2-Receptors Antagonists - Phenothiazines, Prochloropromazine, Perphenazine

Cannabinoids - Nabilone

Dexamthasone

Corticosteroids

Neurokinin-1 Antagonists - Aprepitant

2

What is the physiology of emesis?

  • Controlled by the CNS (medulla)
  • There are 3 major inputs to the dorsal vagal complex:
  • 1) chemoreceptor trigger zone 2) the vagal pathway (GIT pharyx, senses) 3) vestibular pathway (in ear).
  • Need to block the neurotransmitters (and the receptor they come from) involved in the triggering or emesis response:
  • Serotonin -5HT3 Receptors
  • ACh - Muscarinic Receptors
  • Dopamine - D2 Receptor
  • Substance p - NK1 Receptor
  • Histamine - H1 Receptor
  • Enkephalin - Delta Receptor

3

Examples of Histamine H1 Receptor Antagonists

Cyclizine (motion sickness)

Cinnarzine (motion sickness/vestibular disorders)

Promethazine (pregnancy morning sickness)

4

Side effects of H1 receptors

Drowsiness, sedation

5

H3 agonist > Anti vertigo drugs

Betahistine

Hydrochloride

6

What is the role of h3 Agonist

Acts on blood vessel in the inner ear

Side effects are: GI probs, headache, rash, itcing

7

Examples of Muscarinic Receptor Antagonists

  • Hyosine
  • Scopolaimine

8

Side effects of Muscarinic receptor antagonist

  • dry mouth
  • blurred vision
  • less sedative

9

What are Dopamine receptor antagonists

Have a powerful anti-emetic action. Antagoise muscarinic/histamine receptors

 

to treat severe morning sickness

10

Example of a dopamine receptor antagonist to treat morning sickness

  • Phenothiazines

Side effects: sedative, hypotension, dystonia, dyskinsia

11

Example of dopamine receptor antagonist which Penetrates blood brain barrier, Acts on GIT; increasing GI motility

Metoclopramide

Side effects: movement disorders (esp. children), fatigue, motor restlessness, spasmodic torticollis, occulogyric crises, menstruation disorders (via effect on prolactin release), Rare Reactions; QT prolongation

 

12

Example of dopamine receptor antagonist used to treat migraines and cytotoxic therapy-induce emesis 

Domperidone (Motilium, Motillium)

 

side effects: fewer side effects

13

Exampe of serotonin receptor antagonists

Ondansetron

Drug choice for CINV + PONV

 

Side effects: GI upset, headache

other drugs ending in 'tron'

14

Example of neurokinin 1 antagonist

  • Aprepitant

Side effects: fatigue / listlessness, constipation / diarrhea, loss of appetite, hiccups

Rare Side Effects: dizziness, ringing in the ears, hiccups, dyspepsia, diarrhoea, constipation, anorexia; asthenia, headache..

15

Anti -emetics

Vagal pathway

Vestibular pathway

Vommiting centre

Chemoreceptor trigger zone