Chemical. CAS 73210-73-8. Formula C16H25N3O5 • 1/2C4H4O4. MW 339.4 . 58.0. Soluble in water 20mg/ml or DMSO 40mg/ml. 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.