Xamoterol hemifumarate

A phenoxypropanolamine derivative that is a selective partial agonist of beta1-adrenergic receptors (beta1-ARs) (pA2 values are 7.4 - 7.8 and 5.2 - 6.2 at beta1- and beta2-adrenoceptors, respectively), and has shown to improve systolic and diastolic function in studies with heart failure patients. It modulates the sympathetic control of the heart but has no agonist action on beta2-adrenoceptors. Xamoterol has an EC50 value of 80nM for the generation of cyclic AMP (cAMP) in neonatal rat cardiomyocyte cultures. It increases spontaneous contraction of isolated rat right atria (EC50 = 4.67nM). In vivo, xamoterol increases heart rate, an effect that is reversed by the selective beta1-AR antagonist betaxolol but not the selective beta2-AR antagonist ICI 118551.