Salbutamol

Salbutamol is a short-acting beta-2 adrenergic receptor agonist (SABA) and the most widely used reliever inhaler for asthma and chronic obstructive pulmonary disease (COPD) globally.

It acts by selectively stimulating beta-2 adrenoceptors on airway smooth muscle, causing rapid bronchodilation within 3-5 minutes, with peak effect at 15-30 minutes and a duration of action of 4-6 hours.

Salbutamol provides quick relief from acute bronchospasm, exercise-induced bronchoconstriction, and wheezing.

The BNF, NICE, and BTS/SIGN guidelines recommend salbutamol as the first-line reliever for all patients with asthma, to be used as needed for symptom relief.

It does not treat the underlying airway inflammation and should not be used as the sole treatment for asthma (except in patients with very infrequent symptoms).

Overuse of salbutamol (more than 3 times per week for symptoms, or use of 3 or more canisters per year) is a marker of poorly controlled asthma and should trigger clinical review and consideration of regular preventer therapy.

The MHRA and National Review of Asthma Deaths (NRAD) have highlighted that excessive SABA reliance without adequate preventer therapy contributes to avoidable asthma deaths.

Shake the inhaler well before each use. Remove the mouthpiece cover.

Breathe out fully, place the mouthpiece between your lips forming a tight seal, and as you start to breathe in slowly and deeply, press the canister to release one puff.

Continue to breathe in slowly for 3-5 seconds. Remove the inhaler and hold your breath for up to 10 seconds, then breathe out gently.

If a second puff is needed, wait at least 30 seconds before repeating. A spacer device is recommended to improve drug delivery, particularly for children and patients with poor inhaler technique.

Clean the inhaler mouthpiece weekly with a dry cloth. Always carry your reliever inhaler with you.

Acute bronchospasm relief: 1-2 puffs (100-200 mcg) as needed. Up to 4 puffs may be taken for moderate symptoms.

For severe asthma exacerbation: 10 puffs via spacer (give 1 puff at a time, each followed by 5 breaths through the spacer), repeatable every 20 minutes if no improvement while awaiting emergency medical help.

Exercise-induced bronchospasm prevention: 2 puffs 15-30 minutes before exercise.

Maximum recommended dose: 8 puffs per day on a regular basis. If consistently needing more than 8 puffs daily, urgent medical review is essential. Nebulised salbutamol (2.

5-5 mg) is used in hospital for acute severe asthma. No dose adjustment for renal or hepatic impairment.

Side effects per SmPC frequency categories.

Common (≥1/100 to <1/10): Fine tremor (particularly of the hands), headache, tachycardia, palpitations, muscle cramps.

Uncommon (≥1/1,000 to <1/100): Nervousness, agitation, restlessness, hyperactivity (especially in children), dizziness, throat irritation, cough on inhalation, mouth and throat dryness.

Rare (≥1/10,000 to <1/1,000): Hypokalaemia (with high or repeated doses — clinically significant in acute asthma, particularly with concurrent corticosteroids, diuretics, or xanthines), paradoxical bronchospasm (stop and use alternative bronchodilator), cardiac arrhythmias (including atrial fibrillation, supraventricular tachycardia), peripheral vasodilation.

Very rare (<1/10,000): Angioedema, urticaria, hypersensitivity reactions, lactic acidosis (in high-dose intravenous use).

Tremor and tachycardia are dose-dependent and usually mild at standard inhaled doses.

Hypokalaemia is clinically relevant during severe asthma exacerbations requiring high-dose or nebulised salbutamol.

The MHRA and NRAD emphasise that SABA overuse is a risk factor for asthma death.

Prescribers should review patients using 3 or more salbutamol inhalers per year and ensure appropriate preventer therapy is in place.

Salbutamol does not treat airway inflammation; patients with persistent symptoms require regular inhaled corticosteroids.

In acute severe asthma, monitor serum potassium, as salbutamol (especially nebulised or intravenous) can cause significant hypokalaemia, which may be exacerbated by hypoxia, systemic corticosteroids, and theophylline.

Use with caution in patients with thyrotoxicosis, existing cardiovascular disease (ischaemic heart disease, arrhythmias, hypertrophic cardiomyopathy), phaeochromocytoma, and diabetes (may cause hyperglycaemia).

Beta-blockers (including ophthalmic) can reduce salbutamol efficacy and should be avoided in asthma.

Salbutamol is contraindicated in patients with hypersensitivity to salbutamol or any excipient. There are no absolute contraindications to salbutamol use in a life-threatening asthma emergency.

Relative contraindications for routine use include untreated thyrotoxicosis, phaeochromocytoma, and severe tachyarrhythmia. The inhaler is not a substitute for preventer therapy.