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indicationFor symptomatic relief and prevention of bronchospasm due to bronchial asthma, chronic bronchitis, and other chronic bronchopulmonary disorders such as COPD.
pharmacologySalbutamol (INN) or albuterol (USAN), a moderately selective beta(2)-receptor agonist similar in structure to terbutaline, is widely used as a bronchodilator to manage asthma and other chronic obstructive airway diseases. The R-isomer, levalbuterol, is responsible for bronchodilation while the S-isomer increases bronchial reactivity. The R-enantiomer is sold in its pure form as Levalbuterol. The manufacturer of levalbuterol, Sepracor, has implied (although not directly claimed) that the presence of only the R-enantiomer produces fewer side-effects.
mechanism of actionSalbutamol is a beta(2)-adrenergic agonist and thus it stimulates beta(2)-adrenergic receptors. Binding of albuterol to beta(2)-receptors in the lungs results in relaxation of bronchial smooth muscles. It is believed that salbutamol increases cAMP production by activating adenylate cyclase, and the actions of salbutamol are mediated by cAMP. Increased intracellular cyclic AMP increases the activity of cAMP-dependent protein kinase A, which inhibits the phosphorylation of myosin and lowers intracellular calcium concentrations. A lowered intracellular calcium concentration leads to a smooth muscle relaxation and bronchodilation. In addition to bronchodilation, salbutamol inhibits the release of bronchoconstricting agents from mast cells, inhibits microvascular leakage, and enhances mucociliary clearance.
toxicityLD50=1100 mg/kg (orally in mice)
biotransformationHydrolyzed by esterases in tissue and blood to the active compound colterol. The drug is also conjugatively metabolized to salbutamol 4'-O-sulfate.
absorptionSystemic absorption is rapid following aerosol administration.
half life1.6 hours
route of eliminationApproximately 72% of the inhaled dose is excreted in the urine within 24 hours, 28% as unchanged drug and 44% as metabolite.
drug interactionsAmitriptyline: The tricyclic antidepressant, amitriptyline, increases the sympathomimetic effect of salbutamol.
Amoxapine: The tricyclic antidepressant, amoxapine, increases the sympathomimetic effect of salbutamol.
Clomipramine: The tricyclic antidepressant, clomipramine, increases the sympathomimetic effect of salbutamol.
Desipramine: The tricyclic antidepressant, desipramine, increases the sympathomimetic effect of salbutamol.
Doxepin: The tricyclic antidepressant, doxepin, increases the sympathomimetic effect of salbutamol.
Imipramine: The tricyclic antidepressant, imipramine, increases the sympathomimetic effect of salbutamol.
Isocarboxazid: Increased arterial pressure
Linezolid: Possible increase of arterial pressure
Methyldopa: Increased arterial pressure
Midodrine: Increased arterial pressure
Moclobemide: Moclobemide increases the sympathomimetic effect of salbutamol.
Nortriptyline: The tricyclic antidepressant, nortriptyline, increases the sympathomimetic effect of salbutamol.
Phenelzine: Increased arterial pressure
Rasagiline: Increased arterial pressure
Reserpine: Increased arterial pressure