Formoterol fumarate is a long-acting selective beta2-adrenergic agonist (beta2-agonist) with arapid onset of action. Inhaled formoterol fumarate acts locally in the lung as a bronchodilator.In vitro studies have shown that formoterol has more than 200-fold greater agonist activity at beta2-receptors than at beta1-receptors. The in vitro binding selectivity to beta2- over beta1adrenoceptors is higher for formoterol than for albuterol (5 times), whereas salmeterol has ahigher (3 times) beta2-selectivity ratio than formoterol.