anti-emetics

Question 1

how chemotherapy (cisplatin) causes nausea/vomiting

Answer 1

toxic to enterochromaffin cells, causing them to release free radicals, which release lots of 5-HT (seretonin): this 5-HT binds to 5-HT3a receptors in CHEMORECEPTOR TRIGGER ZONE, which activates muscarinic receptors in VOMITING CENTRE= vomiting

Question 2

treatment of chemotherapy induced vomiting

Answer 2

ONDANSETRON: 5-HT3a receptor anatagonist= less activation of CTZ

Question 3

how motion sickness causes nausea/vomiting

Answer 3

causes neural mismatch in labyrinth, which activates H1 receptors on vestibular nuclei, which activates MUSCARINIC receptors on CTZ, which activates muscarinic receptors on VC

Question 4

treatment of motion sickness induced vomiting

Answer 4

promethazine (H1 antagonist) or hyoscine (muscarinic antagonist)

Question 5

gastroparesis induced nausea/vomiting

Answer 5

less emptying of stomach due to less contraction- activates 5HT3a receptors which activates VC

Question 6

treatment of other causes of vomiting eg parkisons drugs/pregnancy/GI issues

Answer 6

METOCLOPRAMIDE- both D2 antagonist (D2 receptros also present on CTZ) and 5-HT3a antagonist

Question 7

side effect of muscarinic receptor antagonist

Answer 7

dry mouth + drowsiness (dizziness)

Question 8

side effect of H1 antagonist

Answer 8

drowsiness (you wanna go sleep during motion sickness

Question 9

side effect of D2 antagonists

Answer 9

extra-pyramidal side effects and galactorrhoea

Question 10

side effects of 5HT3a antagonists

Answer 10

headaches and constipation