Analgesics And Anti-emetics

Question 1

What are the pharmacological targets for anti-emetic drugs?

Answer 1

Histamine receptors (H1)

Serotonin receptors (5HT3)

Muscarinic receptors (M)

Dopamine receptors (D2)

Substance P/Neurokinin (NK1)

Question 2

Which part of the brain controls the vomiting reflex?

Answer 2

The medulla oblongata

Question 3

Name three drugs that are histamine receptor antagonists and their primary uses

Answer 3

Cyclazine -motion sickness

Cinnarizine -motion sickness, vestibular disorders (eg. Vertigo)

Promethazine -severe morning sickness

Question 4

How do hisamine receptor agonists work?

Answer 4

By activating H-receptors on the blood vessels in the inner ear, causing local vasodilation, increased permeability and reversal of the underlying problem of endolymphatic hydrops

Question 5

Give an example of a hisamine receptor agonist

Answer 5

Betahistine hydrochloride

Question 6

Name two muscarinic receptor antagonists and what they are mainly used for

Answer 6

Hyoscine

Scopolamine

Motion sickness and general purpose anti-emesis

Question 7

What are the side effects of muscarinic receptor antagonists?

Answer 7

Dry mouth

Blurred vision

Question 8

Which part of the vomiting reflex do dopamine receptor antagonists work on, and therefore what types of sickness do they prevent?

Answer 8

The chemoreceptor trigger zone:

GI disorders

Viral gastroenteritis

Opioid induced emesis

Uraemia

Question 9

Name three dopamine receptor antagonists

Answer 9

Phenothiazines

Perphenazine

Prochloropromazibe

Metoclopramide

Domperidone

Question 10

Name the serotonin receptor antagonists and the types of emesis they are used against

Answer 10

Ondansetron

Granisetron

Palonosetron

Tropisetron

Used for chemotherapy, anaesthetic and radiation induced emesis

Question 11

When are neurokinin-1 (substance P) receptor antagonists used?

Answer 11

In late phase emesis with cytotoxic drugs: chemotherapy induced and anaesthetic induced emesis

Question 12

Name two NK1 receptor antagonists

Answer 12

Aprepitant

Fosaprepitant

Casopitant

Maropitant

Question 13

What are the side effects associated with substance P antagonists?

Answer 13

Fatigue

Listlessness

Constipation or diarrhoea

Loss of appetite

Hiccups

Dizziness

Tinnitus

Headache

Question 14

What are the different classes of analgesics?

Answer 14

Opioids

Antidepressants

Antiepileptics

Local anaesthetics

Question 15

How do opioids work in pain relief?

Answer 15

By acting at the level of the spinal cord to decrease neurotransmitter release and block postsynaptic receptors

and in the brain stem by activating inhibitory pathways (the body’s own suppression of pain)

Question 16

What are the side effects associated with opioids?

Answer 16

Nausea

Vomiting

Constipation

Drowsiness

Respiratory depression

Hypotension

Sedation

Dependency

Question 17

How do serotonin and noradrenaline reputable inhibitors (SNRI) and selective serotonin reputable inhibitors (SSRI) work to reduce pain?

Answer 17

By preventing the recycling of neurotransmitters, which increases the action of the ascending pain pathways in the brain

Question 18

How do antiepileptic drugs work to reduce pain?

Answer 18

They inhibit voltage-gated Na+ and Ca2+ channels to inhibit action potential firing and to prevent impulse transmission

Enhance neuronal inhibition

Question 19

Which antiepileptic drugs are used for analgesia?

Answer 19

Carbamazepine

Gabapentin

Both used for neuralgia and neuropathic pain

Question 20

How do local anaesthetics work?

Answer 20

By inhibiting voltage-gated Na+ channels or NMDA receptors, which inhibits nerve firing and impulse transmission

Question 21

Which drugs are local anaesthetics?

Answer 21

Lidocaine

Ketamine