Formoterol Fumarate is shown to be a potent β-AR adrenoceptor agonist, with a fast onset of effect on the isolated human bronchus model. This compound demonstrates a 330-fold selectivity for β2 over β1 receptors. Formoterol Fumarate has been reported to be 150-200 times more potent than isoprenaline. This agent has also been noted to reduce the loss of muscle mass in murine models.