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Drug Reference

salbutamol

Short-acting beta-2 agonists· Brands: Ventolin, Airomir, Salamol, Asmasal, Ventodisk, SalbulinINHIVNEBPO

Mechanism of action
Salbutamol is a short-acting beta-2 adrenergic agonist. It stimulates beta-2 receptors in bronchial smooth muscle, activating adenylyl cyclase and increasing intracellular cyclic AMP, leading to smooth muscle relaxation and bronchodilation. It also inhibits release of bronchoconstrictor mediators from mast cells and enhances mucociliary clearance.
Pharmacokinetics
Salbutamol is well absorbed from the respiratory and gastrointestinal tracts. Inhaled salbutamol has an onset of action within 5 minutes and a duration of 4 to 6 hours. Oral administration has an onset of about 30 minutes and similar duration. It undergoes extensive first-pass metabolism in the liver, primarily by sulfation, to the inactive metabolite salbutamol 4-O-sulfate. Excretion is mainly renal, with a small proportion in faeces. Elimination half-life is approximately 2.7 to 5 hours.
Indications & dosing

Acute relief of bronchospasm in asthma or COPD

Two puffs via metered-dose inhaler as required. Adjust to patient response.

  • adult · INH: 100–200 mcg PRN · Two puffs via metered-dose inhaler as required. Adjust to patient response.

Acute severe asthma (nebulised)

Repeat every 20 minutes for up to 3 doses, then as needed.

  • adult · NEB: 2.5–5 mg q20min · Repeat every 20 minutes for up to 3 doses, then as needed.

Exercise-induced bronchospasm prophylaxis

Administer 15 minutes before exercise.

  • adult · INH: 200 mcg single · Administer 15 minutes before exercise.

Acute wheeze in children (nebulised)

Repeat every 20 minutes for up to 3 doses, then as needed.

  • pediatric · NEB: 2.5 mg q20min · Repeat every 20 minutes for up to 3 doses, then as needed.

Hyperkalemia (off-label)off-label

Used as an adjunct to insulin and glucose. Monitor potassium levels.

  • adult · NEB: 10–20 mg single · Used as an adjunct to insulin and glucose. Monitor potassium levels.
Contraindications & precautions
  • Hypersensitivity to salbutamol or any component · Previous serious reaction to salbutamol or its excipients.
  • Non-selective beta-blocker therapy · Non-selective beta-blockers antagonise the bronchodilator effect and may increase risk of adverse effects; consider cardioselective alternatives if beta-blockade is necessary.
  • Use with caution in patients with cardiovascular disease (e.g., ischaemic heart disease, hypertension, arrhythmias) and hyperthyroidism, as beta-agonists can precipitate or worsen these conditions.
  • Use with caution in patients with diabetes mellitus, as salbutamol may increase blood glucose levels.
  • Use with caution in patients with hypokalaemia or risk of hypokalaemia, as salbutamol can lower serum potassium, potentially worsening the condition.
  • Advise patients on correct inhaler technique; excessive use suggests poorly controlled asthma and requires review of therapy.
Adverse effects
  • Tremor
  • Palpitations
  • Tachycardia
  • Headache
  • Muscle cramps
  • Hypokalaemiaserious
  • Paradoxical bronchospasmserious
  • Cardiac arrhythmiasserious
Interactions
  • bisoprololmoderateBeta-blockers blunt bronchodilation; prefer cardioselective agents at low dose in reactive airways.
  • carvedilolmajorAvoid concomitant use of carvedilol with salbutamol in patients with a history of asthma or bronchospastic disease. If beta-blocker therapy is necessary, consider a cardioselective beta-blocker (e.g., bisoprolol, metoprolol) which has lower affinity for beta-2 receptors. Use salbutamol only when needed and monitor respiratory status closely; consider alternative bronchodilators or adjust dose if signs of worsening airway function occur. In patients with heart failure, the benefits of carvedilol may outweigh the risks, but caution and monitoring are essential.
  • digoxinmoderateMonitor serum potassium levels before and during concurrent therapy, especially in patients at risk of hypokalemia (e.g., those on diuretics). Correct hypokalemia promptly. Consider ECG monitoring in patients with symptoms of digoxin toxicity or if potassium falls below 3.5 mmol/L. Avoid excessive salbutamol doses in patients with digoxin toxicity.
  • metoprololmoderateIf co-prescription is necessary, use the lowest effective dose of metoprolol and consider a more cardioselective beta-blocker. Monitor respiratory function, including peak expiratory flow (PEF) or spirometry, and assess the patient's response to inhaled salbutamol. Advise patients to report any increase in shortness of breath or wheezing. In acute bronchospasm, use non-selective beta-agonists or anticholinergics may be considered. Where possible, avoid beta-blockers in patients with known asthma; if required, use cardioselective agents with caution. Regular assessment of clinical response to bronchodilators is essential.
  • propranololmajorAvoid concurrent use of propranolol and salbutamol, especially in patients with asthma or COPD. If an alternative antihypertensive agent is not acceptable, consider a cardioselective beta-blocker (e.g., bisoprolol) at the lowest effective dose. If combined, monitor respiratory function closely, including peak flow or spirometry, and assess symptom control. Advise the patient to report any wheezing, breathlessness, or reduced response to their bronchodilator. Consider increasing the dose of salbutamol or adding an alternative bronchodilator, such as an anticholinergic agent, to maintain airway patency.
Monitoring, pregnancy & toxicity
  • Symptom control (peak expiratory flow, rescue bronchodilator use) · At each review
  • Heart rate and rhythm · During therapy, especially with high doses
  • Serum potassium · In patients receiving high doses or with risk of hypokalemia
  • Tremor and other adverse effects · At each review
  • Pregnancy: Salbutamol can be used during pregnancy for asthma. It is the preferred short-acting beta-2 agonist; use the lowest effective dose. Inhaled therapy is generally safe because systemic exposure after inhalation is low.
  • Toxicity: Tremor, tachycardia, palpitations, nervousness · Supportive care; these effects are usually transient and resolve with dose reduction or discontinuation.
  • Toxicity: Hypokalemia and hyperglycemia · Check serum potassium and glucose; supplement potassium if needed.
  • Toxicity: Severe overdose: metabolic acidosis, seizures, cardiac arrhythmias · Admit to hospital; monitor ECG and electrolytes; consider cardio-selective beta-blocker (e.g., esmolol) under specialist supervision, but avoid in patients with asthma.
Clinical notes
Salbutamol is indicated for the relief of bronchospasm in asthma and chronic obstructive pulmonary disease, and for prevention of exercise-induced bronchospasm. In acute severe asthma, it is often given via nebulisation. Common adverse effects include tremor, palpitations, tachycardia, headache, and muscle cramps. Paradoxical bronchospasm may occur rarely. Caution is needed in patients with cardiovascular disease, hyperthyroidism, and diabetes. Prolonged use may lead to tolerance. In acute severe asthma, repeated dosing is guided by response; ipratropium or corticosteroids may be considered. Practice varies by region and formulary.

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BNF; local formulary