Anti-histamines (Drugs) Flashcards Preview

Mechanism of Drug Action (Drugs) > Anti-histamines (Drugs) > Flashcards

Flashcards in Anti-histamines (Drugs) Deck (24)
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1
Q

What are the anti-histamines?

A
  1. H1 receptor antagonists
  2. H2 receptor antagonists
2
Q

What are the inhibitors of mast cell degranulation?

A
  1. Sodium cromoglycate
  2. Omalizumab
  3. β2-adrenoreceptor agonist
  4. PDE inhibitors
3
Q

What is the mechanism of action of sodium cromoglycate?

A

Stabilises mast cells and prevents degranulation by reducing [Ca2+] influx, possibly by reducing inward Cl- conductance.

4
Q

What is the mechanism of action of omalizumab?

A

Sequesters IgE and prevents binding to FcεR1 receptors.

5
Q

What is the mechanism of action of β2-adrenoreceptor agonists and PDE inhibitors in inhibition of mast cell degranulation?

A

Raised intracellular [cAMP] inhibits mast cell degranulation

6
Q

What are examples of 1st generation H1 receptor antagonists?

A
  1. Mepyramine
  2. Promethazine
7
Q

What are the clinical uses of 1st generation H1 antagonists?

A
  • Sedative
  • Motion sickness
  • Morning sicknes
8
Q

What are examples of 2nd genration H1 antagonists?

A

Terfenadine

9
Q

What are examples of 3rd generation H1 receptor antagonists?

A
  1. Fexofenadine
  2. Loratadine
10
Q

What are the clinical uses of 3rd generation H1 antagonists?

A
  • Hay fever
  • Urticaria
11
Q

What drugs can be used to raise [cAMP]i and inhibit mast cell degranulation?

A
  • β2-adrenoreceptor agonists (e.g. salbutamol)
  • PDE inhibitors (e.g. theophylline)
12
Q

What is the difference between 1st and 2nd generation antihistamines?

A

1st generation crossed BBB and caused CNS effects (e.g. drowsiness due to arousal effects of histamine) while 2nd generation didn’t

13
Q

What was the major side effect of terfenadine?

A
  • Caused long QT syndrome and sudden cardiac death
  • Due to inhibition of hERG channels in cardiac tissue (responsible for repolarisation)
14
Q

What is the pharmacokinetics of terfenadine?

A

Prodrug metabolised to active fexofenadine by cyt3A4 in liver.

15
Q

What drugs are used to treat allergic reactions and mastocytosis?

A
  1. Inhibitors of mast cell degranulation
  2. Anti-histamines
  3. RTK inhibitor (mastocytosis only)
16
Q

What is imatinib used for and its mechanism of action?

A
  • Use: Treatment of mastocytosis
  • Mechanism of action: RTK inhibitor
17
Q

What is a CCK inhibitor?

A

Proglumide

18
Q

What are the H2 receptor antagonists?

A
  • Cimetidine
  • Ranitidine
19
Q

What is a proton pump inhibitor?

A

Omeprazole

20
Q

How is anaphylactic shock treated?

A

IV injection of adrenaline

21
Q

What drugs are used to treat gastric ulcers?

A

Inhibitors of gastric acid secretion:

  1. CCK inhibitors
  2. H2 antagonists
  3. Proton pump inhibitors
  4. Antacids
  5. ACh inhibitors
    (6. Vagotomy, not drug)

Treatment of H. pylori infection: Clarithromycin

22
Q

What is the preferred drugs used for first-line treatment of gastric ulcers clinically?

A

Proton pump inhibitors

23
Q

What is the mechanism of action of misoprostol?

A
  • PGE2 analogue
  • Co-administered with NSAIDs to prevent gastric side-effects
24
Q

What is arthrotec?

A

Diclofenac (NSAID) + Misoprostol