Antihistamines - H1 receptor blocker

Question 1

What is the main compound that is released causing an allergic reaction?

1 - prostoglandin
2 - nitric oxide
3 - histamine
4 - heparin

Answer 1

3 - histamine

Question 2

Which is the main cell responsible for releasing histamine that is key in initiating allergic reactions?

1 - basophils
2 - eosinophils
3 - neutrophils
4 - mast cells

Answer 2

4 - mast cells
- released from storage granules
- basophils can also secrete histamines, just not as much as mast cells

Question 3

Once released by mast cells, which 2 of the following is histamine responsible for?

1 - vasoconstriction
2 - vasodilation
3 - inflammation
4 - coagulation

Answer 3

2 - vasodilation
3 - inflammation

Question 4

Although primarily released by mast cells during an allergic reaction, which 2 of the following can histamine also be produced?

1 - endothelium in afferent arteriole of kidneys
2 - brain as a neurotransmitter
3 - enterochromaffin cells
4 - tunica media of blood vessels

Answer 4

2 - brain as a neurotransmitter
3 - enterochromaffin cells
- involved in gastric acid secretion

Question 5

When a foreign body enters the cell and causes an allergic reaction, B cells become activated and release an antibody that activates mast cells. Which antibody is this?

1 - IgG
2 - IgA
3 - IgM
4 - IgE
5 - IgD

Answer 5

4 - IgE
- IgE cells prime mast cells, so when they come into exposure with pollen they cause granules to be released, which contains histamine

Question 6

H1-receptors are present on endothelium, nerve endings, smooth muscle and in the brain. Which 2 of the following affects do H1 receptors in the endothelium have?

1 - dilation of blood vessels and increased leaking
2 - oedema
3 - erythema
4 - all of the above

Answer 6

4 - all of the above
- oedema and erythema are due to increased blood flow that leaks into tissues

Question 7

H1-receptors are present on endothelium, nerve endings, smooth muscle and in the brain. What affect do H1 receptors on the smooth muscle of the lungs have?

1 - bronchodilation
2 - oedema
3 - erythema
4 -bronchoconstriction

Question 8

H1-receptors are present on endothelium, nerve endings, smooth muscle and in the brain. Which 2 of the following affects do H1 receptors at nerve endings have?

1 - dilation of blood vessels and increased leaking
2 - pain
3 - erythema
4 - itching

Answer 8

2 - pain
4 - itching

Question 9

What type of receptor are H1 receptors?

1 - nuclear receptors
3 - ion channel receptors
3 - GPCRs
4 - enzyme-linked receptors
5 - ligand gates receptors

Answer 9

3 - GPCRs

Question 10

Which of the following is NOT a H1 receptor antagonist, more commonly known as anti-histamines?

1 - Chlorphenamine
2 - Cetirizine
3 - Cyclizine
4 - Ondansetron
5 - Loratadine

Answer 10

4 - Ondansetron
- acts as a 5-HT3 receptor antagonists

Question 11

All of the following are H1 receptor antagonist, more commonly known as anti-histamines that bind and inhibit histamine binding. Is this reversible or irreversible?

• Chlorphenamine
• Cetirizine
• Cyclizine
• Loratadine

Answer 11

• reversible

Question 12

Which of the following conditions are H1 receptor antagonist, more commonly known as anti-histamines not useful in treating?

1 - cellulitis
2 - pruritus (itchyness)
3 - urticaria (hives)
4 - rhinitis (hay fever)
5 - angioedema

Answer 12

1 - cellulitis
- can also be used in anaphylaxis, but only after other life saving treatment has been given

Question 13

All of the following are H1 receptor antagonists, but which one is a 1st generation anti-histamine?

• Chlorphenamine
• Cetirizine
• Cyclizine
• Loratadine

Answer 13

• Chlorphenamine

Question 14

Chlorphenamine is a 1st generation anti-histamine. Which of the following is the key side effect of this medication?

1 - weight loss
2 - hypertension
3 - sedation
4 - rhabdomyolysis

Answer 14

3 - sedation
- drug has high lipid solubility so can cross the blood brain barrier
- histamine regulates wakefulness
- so less histamine causes sedation

Question 15

All of the following are H1 receptor antagonists. Which one of these medications should be avoided in patients with severe liver disease for risk of precipitating hepatic encephalopathy?

• Chlorphenamine
• Cetirizine
• Cyclizine
• Loratadine

Answer 15

• Chlorphenamine

Question 16

All of the following are H1 receptor antagonists. All can be taken orally, but which one can also be given via IV?

• Chlorphenamine
• Cetirizine
• Cyclizine
• Loratadine

Answer 16

• Chlorphenamine
• orally its given every 4-6h