COPD/asthma - therapeutics

Question 1

COPD - approach to treatment 4 steps

Answer 1

1 - short acting bronchodilators PRN ( beta2 agonists or anticholinergics)

2 - short acting bronchodilators plus regular long acting bronchodilators

3 - long acting beta2 agonists plus regular low dose inhaled steroids or regular long acting anticholinergics.

4 - long acting beta2 agonists plus regular low dose inhaled steroids plus regular long acting anticholinergics.

Question 2

why is it better to give resp drugs by inhalation than systemically

Answer 2

50-100 fold lower doses needed.

Question 3

why are inhalers often ineffective

Answer 3

due to poor technique. a spacer can be used if need be.

Question 4

side effects of beta2 agonists

Answer 4

tachcardia arrhythmias, tremor, anxiety, hypokalaemia due to stim of sodium pump. only really at high inhaled doses or when given orally or IV

Question 5

unwanted side effects of corticosteroids

Answer 5

oral candida, hoarse voice. systemic effects are rare with inhaled steroids.

Question 6

general MOA of corticosteroids

Answer 6

via glucocorticoid response elements to change transcription of inflamm genes. for cytokines etc.

Question 7

metabolic effects of corticosteroids

Answer 7

lots. immunosuppression. muscle wasting, hyperglycaemia due to fat breakdown. catabolic so ski thinning, easy bruising, osteoporosis.

mineralocorticoid effects - hypertension. hypokalaemia, oedema.

mood and sleep disturbance.

Question 8

problems with long term corticosteroids.

Answer 8

can switch off pituitary ACTH secretion leading to adrenal atrophy and lack of endogenous production. sudden withdrawal can cause an addisionian crisis.

Question 9

management of an acute exacerbation of COPD

Answer 9

• careful oxygen therapy as chronic CO2 retainers rely on hypoxic drive to breathe.
• regular bronchodilators via nebulisation.
• oral corticosteroids for 7-14 days (40mg prednisolone)
• consider broad spectrum antibiotics for S. pneumoniae, H. influenzae and M. catarrhalis such as amoxicillin.

Question 10

4 steps approach to asthma treatment

Answer 10

1 - short acting bronchodilators PRN (beta2 agonists only)

2 - above plus inhaled steroids.

3 - above plus long acting beta2 agonist usualy in a combo inhaler with the steroids.

4 - increase the inhaled steroid dose or consider leukotriene receptor antagonist (monteleukast).

4 - oral steroids.

Question 11

effect of monteleukast

Answer 11

a leukotriene receptor antagonist . maily bronchodilatory. given orally in maintenance treatment of asthma, blocks the receptors on inflamm cells and smooth muscle.

Question 12

give a methylxanthine

Answer 12

theophylline. can be given orally or IV.blocks adenosine receptors and inhibits phosphodiesterases. causes bronchodilation.

Question 13

side effects of methylxanthines

Answer 13

• most toxic bronchodilator
• very narrow therapeutic index
  = GI problems eg nausea, vomit, diarrhoea,
• cardiac disturbances such as tahcy and arrhythmias.
• CNS stim = headaches, insomnia, convulsions…

Question 14

example of a cromolyn

Answer 14

sodium cromoglycate. inhaled. high treatment failure rate. MOA unknown, prevents mast cell degranulation in vitro.
- few adverse effects but weak.