Physiology and Pharmacology: (Challis) 11 Asthma Flashcards

1
Q

What is asthma and what does it result in

A

Chronic inflammatory disease of the airways

  • results in airways hyperresponsiveness
  • further resulting in ‘reversible’ airway obstruction
  • though hypertrophy/hyperplasia
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2
Q

How can difficulty breathing be quantified?

A

Measured through FEV1 (Forced expiratory volume in 1 second)

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3
Q

What effect does an allergen have on response with regards to time?

A

Initial response in attack termed ‘early phase’
- around %60 FEV1 capacity

Some sufferers experience late phase hours later
- more severe broncho-constriction than early phase

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4
Q

Mechanism of early phase attack

A

Eliciting agent
-> stimulates mast cells

  • > release of spasmogens, chemotaxins and chemokines
  • > spasmogens cause bronchospasm
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5
Q

Mechanism of late phase attack

A

Infiltration of cytokine releasing TH2 cells + inflammatory cells e.g. eosinophils

  • > mediators, EMBP, ECP released
  • >
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6
Q

Define prophylaxis

- example of agents used

A

Prevent/reduce inflammation using anti-inflammatory agents e.g. using corticosteroids

  • beclomethasone
  • fluticasone
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7
Q

Problems associated with chronic corticosteroid dosing

  • newer corticosteroids minimize risks how? example of one?
A
  • Cushing’s syndrome
  • Thinning of skin / easy bruising
  • Increased risk of infection
  • Increased abdominal fat
  • Negative Ca2+ balance -> osteoporosis

New steroid Fluticazone minimises side effects by

  • direct delivery to lungs
  • favourable pharmacokinetics (poor systemic absorbance, hangs around in airways, any in blood quickly metabolised by liver)
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8
Q

Treatments for symptomatic relief? Examples + why they are effective

A

Rapid reversal of bronchoconstriction -> Beta2-selective adrenoceptor agonists

e.g. salbutamol, terbutaline, salmeterol

Effective because they relax bronchoconstriction irrespective of cause

  • stimulates muscle relaxation
  • inhibit mucus secretion
  • decrease tissue oedema
  • may possess some anti-inflammatory activity
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9
Q

Why choose a B2 selective agonist when treating asthma over a non-selective B adrenoceptor agonist?

A

Minimise side effects -> non-selective agonist will relieve symptoms but also stimulate heart beat speed, contractile strength

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10
Q

Explain the long-acting nature of salmeterol

A

Due to the long hydrophobic tail of the molecule that acts like a leash, tethering the molecule to the receptor

this means that the agonist can later re-assert agonist action when the site is free, regardless if a molecule was bound to the site beforehand

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