Antiasthmatics

Question 1

Why are inhaled corticosteroids often used to control asthma?

Answer 1

Fast acting due to lipophilicity
High receptor binding affinity
Required at low dosage
Extensive first-pass effect hence less systemic side effects

Question 2

Montelukast mechanism of action

Answer 2

Competitive antagonist against cysteinyl leukotriene receptor

Question 3

Effects of fluticasone

Answer 3

Reduced inflammation
Reduced airway hyperresponsiveness in a few weeks
Increases resolution

Question 4

AE of inhaled corticosteroids

Answer 4

Oropharyngeal candidiasis
Cough
Adrenal suppression
Osteoporosis

Question 5

What types of asthma does montelukast treat

Answer 5

Prophylaxis and chronic asthma

Aspirin or exercise-induced asthma

Question 6

Sodium cromoglycate mechanism of action

Answer 6

• Inhibits mast cell degranulation induced by IgE-mediated cross-linking to prevent histamine, prostaglandin and leukotriene release
• Promotes Annexin A1 secretion to block histamine and eicosanoid release from mast cells
• Blocks inflammatory mediator release from eosinophil, neutrophil and macrophages
• Prevents cold, dry air and exercise-induced bronchospasm

Question 7

AE of sodium cromoglycate

Answer 7

Dry mouth, throat irritation, coughing

Question 8

Omalizumab mechanism of action

Answer 8

Binds to free IgE to reduce cell-bound IgE, decrease expression of high affinity receptors, reduce mediator release, allergic inflammation

Question 9

List the types of asthma relievers

Answer 9

B2 agonists
Methylxanthines
Muscarinic antagonists
Ipratropium bromide
Tiotroprium bromide

Question 10

Why are b2 agonists used with ICS?

Answer 10

• ICS upregulates b2 receptor expression
• Effective anti-inflammatory
• Decreased mucus hypersecretion
• Decreased airway hypersensitivity
• Decreased eosinophilia

Question 11

AE of b2 agonist

Answer 11

Fine tremor of skeletal muscle
Muscle cramps
Peripheral vasodilation
Tachycardia
Hypokalemia
Hyperglycemia

Question 12

Pathway of salbumatol to ASM relaxation

Answer 12

Salbutamol binds to b2 GPCR, increasing adenylyl cyclase levels which increases cAMP levels. This decreases intracellular Ca2+, myosin light chain kinase and increases K+ conductance. Calcium forms complex with MLCK, which when phosphorylated, causes smooth muscle contraction. Thus, their lowered levels results in ASM relaxation.

Question 13

Theophylline mechanism of action

Answer 13

1) Inhibits PDE to prevent cAMP breakdown
2) Blocks adenosine receptor to prevent bronchoconstriction
3) Increase epinephrine release from adrenal medulla to increase binding to b2 receptor

Question 14

When is ipratropium bromide and tiotropium bromide used?

Answer 14

COPD

Question 15

AE of IB and TB?

Answer 15

Dry mouth, elderly urinary retention, paradoxical bronchospasm

Question 16

Typical asthma rescue therapy?

Answer 16

ICS + formoterol (LABA)