Salbutamol is a selective beta2-adrenoceptor agonist. At therapeutic doses, it acts on the beta 2-adrenoceptors of bronchial smooth muscle, with little or no action on the ?1-adrenoceptors of cardiac muscle. Salbutamol provides short acting (4-6 hours) bronchodilatation with a fast onset (within 5 minutes) in reversible airways obstruction. It also has an anti-inflammatory effect on mast cells causing inhibition of release of bronchoconstrictor mediators including histamine, neutrophil chemotactive factor (NCF) and prostaglandin D2.