Salbutamol

Question 1

Mechanism of Action (nebulised salbutamol)

Answer 1

1. Salbutamol is an agonist of beta-2 receptors which are found in smooth muscle cells of bronchioles, skeletal muscle, uterus, mast cells, liver cells and blood vessels
2. Stimulation of these receptors causes bronchodilation, muscle tremors, relaxation of the pregnant uterus, decreased bile production, increases glycogenolysis, mast cell stabilisation and vasodilation of blood vessels (increasing blood flow to brain, heart, kidneys and skeletal muscle)

Question 2

Indications (nebulised salbutamol)

Answer 2

1. Bronhospasm secondary to asthma or COPD
2. Prominent bronchospasm secondary to airway burns, smoke inhalation or chest infection
3. Release syndrome following crush injury

Question 3

Contraindications (nebulised salbutamol)

Answer 3

Known severe allergy

Question 4

Cautions (nebulised salbutamol)

Answer 4

None

Question 5

Pharmacokinetics (nebulised salbutamol)

Answer 5

1. Inhaled salbutamol is absorbed through the lungs and some is swallowed
2. Salbutamol is metabolised in the liver and excreted in urine
3. There are no significant effects from liver or kidney impairment

Question 6

Common adverse effects (nebulised salbutamol)

Answer 6

1. Tremor
2. Tachycardia

Question 7

Onset and duration of effect (nebulised salbutamol)

Answer 7

1. Onset 2-5 minutes
2. Duration 1-2 hours

Question 8

Dosage (nebulised salbutamol)

Answer 8

1. 5mg for adults and children

Extra: initial dose combined with 0.5mg Ipratropium but repeated doses are not. Ipratropium is not administered for release syndrome secondary to crush injury