REVIEW N,O-Dibenzylated formoterol is an advanced intermediate used in the preparation of formoterol hemifumarate which is a potent, selective and long-acting beta2-adrenoceptor agonist to beta2 and beta1 receptors with pKd of 8.12 and 5.58, respectively. Formoterol hemifumarate reveals 330-fold selectivity for beta2 over beta1 receptors. Formoterol hemifumarate potently relaxes guinea pig trachea (pD2 = 9.29), and is longer-acting and 100-fold more potent than salbutamol. Formoterol hemifumarate works like other beta2-agonists, causing bronchodilation by relaxing the smooth muscle in the airway so as to treat the exacerbation of asthma. The long duration of formoterol action occurs because the formoterol molecules initially diffuse into the plasma membrane of the lung cells, and then are slowly released back outside, where they can come into contact with beta2 adrenergic receptors. Formoterol is used in the treatment of used in the management of asthma and/or chronic obstructive pulmonary disease (COPD).