Salbutamol is a short-acting, selective beta2-adrenergic receptor agonist (SABA) used primarily as a bronchodilator for the relief and prevention of bronchospasm in reversible obstructive airway diseases. The 4mg tablet formulation is an oral preparation used for maintenance therapy and prophylaxis, particularly in patients who cannot use inhalers effectively. It is a cornerstone in the management of asthma and COPD in the Indian clinical setting.
Adult: Initial: 2mg to 4mg three or four times daily. Maintenance: 4mg three or four times daily. Maximum: 16mg per day in divided doses.
Note: Tablet should be swallowed whole with a glass of water, with or without food. If gastrointestinal upset occurs, take with food. Do not crush or chew unless advised (some brands may be scored). Maintain regular dosing intervals. Not for acute attacks.
Salbutamol acts as a selective agonist at beta2-adrenergic receptors located on bronchial smooth muscle cells. Activation of these G-protein coupled receptors stimulates adenylate cyclase, increasing intracellular cyclic AMP (cAMP). Elevated cAMP activates protein kinase A (PKA), which phosphorylates and inactivates myosin light-chain kinase, leading to smooth muscle relaxation and bronchodilation. It also inhibits the release of bronchoconstrictive mediators from mast cells.
Pregnancy: Pregnancy Category C (US FDA). Should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Inhaled salbutamol is preferred. Oral use may be considered for maintenance if inhalers are ineffective. Not recommended for tocolysis in oral tablet form.
Driving: May cause dizziness, nervousness, or tremor. Patients should not drive or operate machinery until they know how the medication affects them.
| Beta-blockers (e.g., Propranolol, Atenolol) | Antagonizes bronchodilator effect of salbutamol; may cause severe bronchospasm in asthmatics. | Major |
| Diuretics (especially loop and thiazide diuretics) | Additive hypokalemic effect; risk of severe hypokalemia and cardiac arrhythmias. | Major |
| Digoxin | Hypokalemia induced by salbutamol may increase risk of digoxin toxicity (arrhythmias). | Moderate |
| Monoamine Oxidase Inhibitors (MAOIs) and Tricyclic Antidepressants (TCAs) | May potentiate the cardiovascular effects (tachycardia, hypertension) of salbutamol. | Moderate |
| Other Sympathomimetic agents (e.g., Decongestants, Theophylline) | Additive sympathomimetic side effects (tremor, tachycardia, nervousness). | Moderate |
| Corticosteroids (Systemic) | Additive hypokalemic effect. | Moderate |