Bronchodilators and immune suppressants in airway disease

Question 1

Leukotriene receptor antagonist (Monteleukast): Mechanism of action

Answer 1

LTC4 release by mast cells and eosinophils can induce bronchoconstriction, mucus secretion and mucosal oedema, and promote inflammatory cell recruitment
LRAs block the effect of cysteinyl leukotrienes in the airways at the CysLT1 receptor

Question 2

Leukotriene receptor antagonist (Monteleukast): Side effects

Answer 2

Angioedema
Dry mouth Anaphylaxis Arthralgia
Fever
Gastric disturbances 
All very rare

Question 3

Leukotriene receptor antagonist (Monteleukast): Cautions

Answer 3

Churg-Strauss syndrome has occurred very rarely in association with the use of montelukast; in many of the reported cases the reaction followed the reduction or withdrawal of oral corticosteroid therapy. Prescribers should be alert to the development of eosinophilia, vasculitic rash, worsening pulmonary symptoms, cardiac complications, or peripheral neuropathy.

Question 4

Leukotriene receptor antagonist (Monteleukast): Dose

Answer 4

10 mg once daily,

Question 5

Methylxanthines (e.g. Aminophylline and Theophylline): Mechanism of action

Answer 5

Non-selective phosphodiesterase inhibitors that prevent the degradation of cAMP, also act as adenosine receptor antagonists.

Question 6

Methylxanthines (e.g. Aminophylline and Theophylline): Effects

Answer 6

The combined effect is smooth muscle relaxation and bronchodilation.

Question 7

Methylxanthines (e.g. Aminophylline and Theophylline): Side Effects

Answer 7

Narrow therapeutic window
Frequent side-effects – nausea, headache, reflux
Tachycardia
Arrhythmias, fits

Question 8

Methylxanthines (e.g. Aminophylline and Theophylline): Cautions

Answer 8

levels increased by cytochrome P450)inhibitors eg erythromycin, ciprofloxacin

Question 9

Methylxanthines (e.g. Aminophylline and Theophylline): Dose

Answer 9

Narrow margin between therapeutic dose and toxic dose - must check levels

sever acute asthma IV infusion 500-700 micrograms/kg/hour adjusted to blood concentration

oral 225 mg BD