S11) Pharmacology of Airway Control Flashcards

1
Q

Describe the autonomic innervation of the airway smooth muscle

A
  • Parasympathetic (dominant) – bronchoconstriction, vascular dilatation, increased secretion from mucus glands
  • Sympathetic – innervates vascular smooth muscle & glands (doesn’t affect airway, but β-adrenoreceptors found in airway smooth muscle)
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2
Q

What does asthma control mean?

A
  • Minimal symptoms during day and night
  • Minimal need for reliever medication
  • No exacerbations
  • No limitation of physical activity
  • Normal lung function (FEV1 and/or PEF >80% predicted or best)
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3
Q

Outline the stepwise treatment approach for asthma

A
  • Step 1 – short acting β2 agonists, consider low dose ICS
  • Step 2 – regular low dose ICS
  • Step 3

A. LABA + low dose ICS

B. LABA + ↑ dose ICS / stop LABA if no effect

  • Step 4 – LABA + high dose ICS (can add LTRA/aminophylline)
  • Step 5 – daily oral steroid + high dose ICS + consider others
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4
Q

What is used to treat mild intermittent asthma in Step 1 of asthma control?

A

Mild intermittent asthma – short-acting β2-agonists e.g. salbutamol, terbutaline

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5
Q

Describe the Step 1 treatment aims in asthma control

A
  • Symptom relief through reversal of bronchoconstriction
  • Used on an as-required basis (not regularly)
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6
Q

Describe the site and/or mechanism of action of β2 agonists in Step 1 of asthma control

A
  • Acts predominantly on airway smooth muscle
  • Potentially inhibits mast cell degranulation (if used intermittently)
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7
Q

Illustrate the β2 receptor function in airway smooth muscle

A
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8
Q

Classify the different inhaled β2 agonists in terms of the speed of onset and the duration of action

A
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9
Q

Identify some side effects of β2 agonists

A

Adrenergic i.e. tachycardia, palpitations, tremor

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10
Q

What is used as regular preventer therapy in Step 2 of asthma control?

A

Regular preventer therapy – inhaled corticosteroids

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11
Q

What are the four conditions one must consider before starting Step 2 in the asthma control for a patient?

A
  • Using β2 agonist ≥ 3 times/week
  • Symptoms ≥ 3times/week
  • Waking ≥ 1time/week
  • Exacerbation requiring oral steroids in last 2 years
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12
Q

What are the aims of Step 2 treatment in asthma control?

A
  • Improve symptoms
  • Improve lung function
  • Reduce exacerbations
  • Prevent death
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13
Q

Illustrate the systemic availability of inhaled drugs

A
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14
Q

Provide some examples of inhaled corticosteroids

A
  • Budesonide
  • Beclomethasone
  • Fluticasone
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15
Q

Provide an example of a combined LABA and steroid

A

Symbicort

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16
Q

Provide an example of a leukotriene receptor antagonists

A

Montelukast

17
Q

What are some ADRs for leukotriene receptor antagonists?

A
  • Angioedema
  • Dry mouth
  • Anaphylaxis
  • Arthralgia
  • Fever
18
Q

Describe the mechanism of action for LTRAs

A
  • LTRAs lock the effect of cysteinyl leukotrienes in the airways at the CysLT1 receptor
  • Leukotrienes are released by mast cells/eosinophils, induce bronchoconstriction, mucus secretion and mucosal oedema and promote inflammatory cell recruitment
19
Q

Provide some examples of methylxanthines

A
  • Theophylline
  • Aminophylline
20
Q

Describe the mechanism of action for methylxanthines

A
  • Antagonise adenosine receptors
  • Inhibit phosphodiesterase
  • Increase cAMP
21
Q

What are the ADRs for methylxanthines?

A
  • Common – nausea, headache, reflux
  • Potentially life-threatening toxic complications – arrhythmias, fits
22
Q

What possible drug interactions might methylxanthines have?

A

Levels increased by CYP450 inhibitors e.g. erythromycin, ciprofloxacin

23
Q

Provide some examples of long acting anticholinergics

A
  • Tiotropium bromide
  • Glycopyrronium
24
Q

What are the indications for LAMAs?

A
  • COPD
  • Severe asthma
25
Q

Describe the mechanism of action for long acting anticholinergics

A

LAMAs bind to M3 muscarinic receptor and block it’s action (prevent bronchoconstriction)

26
Q

What are the ADRs of LAMAs?

A

Anticholinergic – dry mouth, urinary retention, glaucoma

27
Q

Describe the mechanism of action of omalizumab (anti-IgE)

A

Biological therapies:

  • Prevents IgE binding to high affinity IgE receptor
  • Cannot bind to IgE already bound to receptor, so cannot cross-link IgE and activate mast cells
28
Q

Describe the mechanism of action of reslizumab (Anti IL-5)

A

Biological therapies:

  • Reduce peripheral blood and airway eosinophil numbers
  • Most effective at reducing rate of severe asthma exacerbations