Airway Control

Question 1

describe the principles of management of the 5 step approach in asthma

Answer 1

start on step most appropriate to severity

once controlled, step down if possible

control = symptoms minimised day and night, minimal need for reliever meds, no exacerbations, no limitation of physical activity, normal lung function

always review inhaler technique & any trigger factors

Question 2

Bronchidilators:
what they are used for
mechanism of action
administration
ADRs
DDIs

Answer 2

symptom reflief & reversal of bronchoconstriction

bind B2 adrenoceptors in bronchial smooth msuc
= increased cAMP
subsequent decreased [Ca], reducing binding of Ca to troponin preventing musc contraction
optimal deposition in pulmonary tract with particle size 1-5 microns
variation in half lives of different drugs determines therapeutic dose
(fast acting - immediate use/relievers, slow acting - adjuvant with corticosteroid)

aerosol, powder, nebulised, IV

high doses = systemic adrenergic effects = tachycardia, palpitatons, tremors (minimised with inhaled administration)

interacts with Beta antagonists (beta blockers) e.g. propanolol:
these bind to both B1 & 2 adrenoceptors causing asthma symptoms

Question 3

Corticosteroids:
what they are used for
route of administration
mechanism of action
ADRs

Answer 3

longer term management of asthma (glucocorticoids), especially eosinophilic asthma

inhalation, orally

anti-inflammatory effect: suppress gene transcription in inflammatory cells
repress inflammatory responses
induce apoptosis in inflammatory cells, reducing number of mast cells

newer drugs have fewer ADRs because designed to have poor systemic absorption
croaky voice, sort throat, thrush

Question 4

Leukotrine receptor antagonists:
what they are used for
overall mechanism of action
overall ADRs
2 types

Answer 4

add-on therapy in asthma

prevent release of LTC leukotrine from mast cells and eosinophils, which normally induce bronchoconstriction, mucus secretion, mucosal oedema and promote inflammatory cell recruitment

angioedema, dry mouth, anaphylaxis, arthralgia, fever, gastric disturbances

Anticholinergics, Methylanthines

Question 5

Anticholinergics (a Leukotrine receptor antagonist):
examples
mechanism of action
ADRs

Answer 5

Ipatropium, Tiotropium (longer acting)

muscarinic receptor antagonists
bind to and block action of M2 muscarinic receptors
preventing bronchoconstriction and inhibiting mucus secretion

Tiotropium ADRs: dry mouth, urinary retention, glaucoma

Question 6

Methylanthines (a Leukotrine receptor antagonist):
examples
mechanism of action
ADRs

Answer 6

theophylline, aminophylline

mechanism not entirely understood, but thought to antagonise adenosine receptors

psychomotor agitation, tachycardia

Question 7

treatment of acute severe asthma

Answer 7

OSHIT:
Oxygen (high flow)
Salbutamol (nebulised)
Hydrocortisone/Prednisolone
Ipatropium (if not responding to above or life threatening)
Theophylline (aminophylline IV)

Question 8

What is the 5 step approach in asthma treatment

Answer 8

1. inhaled short acting B2 agonist when required (e.g. salbutamol)
2. add inhaled steroids (e.g. beclomethasone)
3. add inhaled long acting B2 agonist (e.g. salmeterol)
4. increase inhaled steroid levels or add 4th drug (i.e. leukotrine receptor antagonist, theophylline or oral B2 agonist(
5. add oral steroid or anti-IgE