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Pharmacology - Year 2 AC > Week 5 - Asthma > Flashcards

Week 5 - Asthma Flashcards

1
Q

What are the main first line drugs of asthma?

A

Glucocorticoids (steroids)

B2 adrenergic agonists

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2
Q

Where is the site of bronchodilator action?

A

Smooth muscle in the bronchiole walls

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3
Q

Name the types of bronchodilator

A

B2 adrenergic receptor agonists

Theophylline

Muscarinic receptor antagonists

Leukotriene receptor antagonists

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4
Q

What is the mechanism of action of B2 adrenergic receptor agonists?

A

Direct action on B2 adrenoreceptors on bronchiole smooth muscle to relax muscle

Also:
Inhibit mediator release from mast cells and monocytes

May act on cilia to increase mucus clearance

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5
Q

Name the shorter acting B2 adrenergic receptor agonists and what their duration of action is

A

Salbutamol
Terbutaline

  • max effect within 30 mins
  • lasts 4-6 hours
  • used “as needed” to control symptoms
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6
Q

Name the longer acting B2 adrenergic receptor agonists and what their duration of action is

A

Salmeterol

  • duration of action = 12 hours
  • 2X daily in patients not controlled with glucocorticoids
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7
Q

How are B2 agonists administered and why?

A

Inhalation

  • to target action in lung
  • minimise systemic effects
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8
Q

What are the unwanted effects of B2 agonists?

A
  • most common = tremor (activate B2 receptors in skeletal muscle)
  • result from absorption in to systemic circulation

-some tolerance to them may be developed (receptors get desensitised) - prevent by use of a glucocorticoid

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9
Q

What is the mechanism of action of theophylline?

A

Phosphodiesterase (PDE) inhibitor

-mechanism still unclear

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10
Q

How is theophylline administered?

A

Orally (sustained release tablet)

IV in acute severe asthma (can’t inhale anything far enough)

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11
Q

When is theophylline used?

A

Second line drug

-used with steroid when asthma response to B2 agonist is inadequate

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12
Q

What are the side effects of theophylline?

A
  • CNS - stimulant (tremor, sleep disturbance)
  • CV (stimulates heart, vasodilation)
  • GI tract (anorexia, N+V)
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13
Q

What are the actions of muscarinic antagonists?

A

Block action of endogenous acetylcholine at muscarinic receptors

  • relax bronchial smooth muscle - bronchodilatoion
  • inhibit elevated mucus secretion in asthma
  • may increase clearance of bronchial secretions
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14
Q

What is the main muscarinic receptor antagonist used?

A

Ipratropium

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15
Q

When are muscarinic receptor antagonists used?

A

-adjunct to B2 agonists and steroid when these are insufficient

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16
Q

How are muscarinic receptor antagonists administered and what is their duration of action?

A
  • aerosol inhalation
  • max effect 30 mins, lasts 3-5 hours
  • poorly absorbed in to systemic circulation
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17
Q

What are the side effects of muscarinic receptor antagonists?

A

Few unwanted effects - safe, well tolerated

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18
Q

What is the mechanism of action of leukotriene antagonists?

A
  • act at cysteinyl-leukotriene receptors on bronchiole smooth muscle cells
  • prevent actions of LTC4 and LTD4 which are bronchial spasmogens and stimulate mucus secretion
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19
Q

Name some leukotriene receptor antagonists

A

Montelukast (1X daily)

Zafirlukast (2X daily)

20
Q

How are leukotriene receptor antagonists administered?

A

Orally

21
Q

What are leukotriene receptor antagonists used for?

A
  • prevent exercise induced and aspirin sensitive asthma
  • action additive with B2 agonists
  • main use as add on for uncontrolled, mild-moderate asthma
22
Q

What does aspirin block in asthma?

A

The cyclooxygenase pathway

Therefore more leukotrienes are produced instead of prostaglandins because the pathway is sent to the right

23
Q

What are the side effects of leukotriene antagonists?

A

Headache

GI disturbances

24
Q

What is the mechanism of action of glucocorticoids?

A
  • enter cells
  • bind to intracellular receptors in cytoplasm - GRa and GRb
  • receptor complex moves to nucleus
  • binds to DNA in nucleus
  • alters gene transcription (repression of IL-3)
25
Q

What are the actions of glucocorticoids?

A

Reduce production of

  • cytokines
  • spasmogens (LTC4, LTD4)
  • leukocyte chemotaxins (LTB4, PAF)

Therefore reduce:

  • bronchospasm
  • recruitment and activation of inflammatory cells
26
Q

Name some glucocorticoids

A

Beclometasone diproprionate
Budesonide
Fluticasone propionate

Occasionally prednisolone or hydrocortisone

27
Q

How are glucocorticoids administered and how long does it take for an effect to take place?

A

Usually given by inhalation (metered dose inhaler, localises effect in lung)

Full effect takes several days to develop

28
Q

Which glucocorticoids are often given for acute exacerbations?

A

Hydrocortisone

Oral prednisolone

29
Q

What are the side effects of glucocorticoids?

A

-uncommon with inhaled steroids

-oropharyngeal thrush and dysphonia
(Minimised using spacer)

  • oral/regular large doses -serious effects
  • e.g. Adrenal suppression - pts carry steroid card
30
Q

What is the mechanism of action of cromoligate?

A

Not fully understood

-mast cell stabiliser (but not main action)

31
Q

How is cromoligate administered?

A

Inhalation - aerosol, nebuliser solution or powder

Prophylactic use

  • prevent both phases of attack
  • most effective in children
  • effects may take weeks to develop
32
Q

What are the side effects of cromoligate?

A
  • irritation of upper respiratory tract

- hypersensitivity reactions reported - rare

33
Q

What is the drug related to cromoligate?

A

Nedocromil sodium

34
Q

Who responds to chromoligate?

A

Not all asthmatics respond

  • unpredictable
  • children respond better than adults
35
Q

What does cromoligate do?

A
  • can reduce both early and late phase responses
  • reduce bronchial hyper-reactivity
  • effective in asthma caused by - antigen, exercise, irritants
36
Q

What does lipocortin do?

A

Inhibitor of phospholipase A2

  • lose production of leukotrienes
  • reduced inflammation in tissue
37
Q

What are biologic agents?

A
  • new development
  • recombinant DNA-derived humanised IgG1 monoclonal antibody
  • binds to human IgE, inhibits binding of IgE to IgE receptor on the surface of mast cells and basophils
  • inhibits IgE mediated cascade of asthma
38
Q

Name a biologic agent

A

Omalizumab

39
Q

How are biologic agents administered?

A

Sub cut injection every 2-3 weeks

  • absorbed slowly
  • peak plasma conc. in 7-8 days
40
Q

What does the IgE antibody cause?

A

Inflammatory cell recruitment –> bronchoconstriction

41
Q

What are the side effects of Omalizumab? (Biologic agent)

A

Few but can be severe

  • anaphylaxis - allergic reaction to protein
  • malignancies (slightly higher rate than normal)
42
Q

What would be used to treat a mild asthmatic with rare attacks?

A

Inhaled B2 agonist when required

43
Q

What would be used to treat a mild asthmatic with frequent attacks?

A
  • glucocorticoid for prophylaxis

- B2 agonist when needed for acute attack

44
Q

What would be used to treat moderate to severe asthma?

A

-drug combination preferred

  • usually B2 agonist with glucocorticoid
  • a combined inhaler
45
Q

What are the aims of drug treatment in asthma?

A
  • to reduce inflammation
  • to prevent bronchoconstriction
  • to restore airways calibre to normal

Pharmacology - Year 2 AC (14 decks)

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