Pharmacology Of Asthma

Question 1

Salbutamol mechanism of action

Answer 1

Agonist at the β2 receptor on airway smooth muscle cells. Activation reduces Ca2+ entry and this prevents smooth muscle contraction.

Question 2

Drug target of salbutamol

Answer 2

Beta 2 adrenergic receptor

Question 3

Side effects of salbutamol

Answer 3

Palpitations/ agitation
Tachycardia/ Arrythmias
Hypokalaemia (at higher doses)

Question 4

Extra info on salbutamol

Answer 4

Salbutamol is a short acting beta agonist (SABA). It’s half life is 2.5-5hours.

Beta 2 selectivity is not absolute – as a result, cardiac (beta 1) effects can be seen.
Hypokalaemia can be caused via an effect on sodium/ potassium ATPase. This effect can be exacerbated by coadministration with corticosteroids

In 2020, salbutamol was the 12th most commonly prescribed drug in the West London area

Question 5

Fluticasone mechanism

Answer 5

Very powerful drugs. Multiple actions on many different cell types. Fluticasone directly decreases inflammatory cells such as eosinophils, monocytes, mast cells, macrophages, and dendritic cells. It reduces the number of these cells and also the number of cytokines they produce.

Question 6

Fluticasone drug target

Answer 6

Glucocorticoid receptor

Question 7

Fluticasone side effect

Answer 7

Local side effects:
Sore throat, hoarse voice, opportunistic oral infections

Systemic side effects:
Growth retardation in children
Hyperglycaemia
Decreased bone mineral density
Immunosuppression
Effects on mood
(Many others)

Question 8

Fluticasone extra info

Answer 8

Greater affinity for the glucocorticoid receptor compared to cortisol.

Oral bioavailability <1%. Therefore, any systemic delivery via the inhaled route is predominantly through the pulmonary vasculature.

In 2020, fluticasone was the 72nd most commonly prescribed drug in the West London area

Question 9

Mometasone mechanism of action

Answer 9

Very powerful drugs. Multiple actions on many different cell types. Mometasone directly decreases inflammatory cells such as eosinophils, monocytes, mast cells, macrophages, and dendritic cells. It reduces the number of these cells and also the number of cytokines they produce.

Question 10

Mometasone target

Answer 10

Glucocorticoid receptor

Question 11

Mometasone side effects

Answer 11

Local side effects:
Sore throat, hoarse voice, opportunistic oral infections

Systemic side effects:
Growth retardation in children
Hyperglycaemia
Decreased bone mineral density
Immunosuppression
Effects on mood
(Many others)

Question 12

Mometasone extra info

Answer 12

Greater affinity for the glucocorticoid receptor compared to cortisol.

Oral bioavailability <1%. Therefore, any systemic delivery via the inhaled route is predominantly through the pulmonary vasculature.

In 2020, mometasone was the 62nd most commonly prescribed drug in the West London area

Question 13

Budesonide mechanism of action

Answer 13

Budesonide Very powerful drugs. Multiple actions on many different cell types. Budesonide directly decreases inflammatory cells such as eosinophils, monocytes, mast cells, macrophages, and dendritic cells. It reduces the number of these cells and also the number of cytokines they produce.

Question 14

Budesonide drug target

Answer 14

Glucocorticoids receptor

Question 15

Budesonide side effect

Answer 15

Local side effects:
Hoarse voice, opportunistic oral infections

Systemic side effects:
Growth retardation in children
Hyperglycaemia
Decreased bone mineral density
Immunosuppression
Effects on mood
(Many others)

Question 16

Extra info on Budesonide

Answer 16

Oral bioavailability >10%. Therefore, inhaled budesonide will still result in some systemic absorption through the gastro-intestinal tract.

Less potent than fluticasone and mometasone

In 2020, budesonide was the 71st most commonly prescribed drug in the West London area

Question 17

Montelukast mechanism of action

Answer 17

Antagonism of CysLT1 leukotriene receptor on eosinophils, mast cells and airway smooth muscle cells decreases eosinophil migration, broncho-constriction and inflammation induced oedema

Question 18

Montelukast target

Answer 18

CysLT1 leukotriene receptor

Question 19

Side effects of Montelukast

Answer 19

Mild side effects:
Diarrhoea
Fever
Headaches
Nausea or vomiting

Serious side effects:
Mood changes
Anaphylaxis

Question 20

Extra info of Montelukast

Answer 20

For prophylaxis of exercise-induced bronchoconstriction, montelukast should be administered at least 2 hours before initiating exercise.

In 2020, montelukast was the 95th most commonly prescribed drug in the West London area