Regadenoson is an A2A adenosine receptor agonist that is a coronary vasodilator that is commonly used in pharmacologic stress testing. Target: A2A adenosine receptor Regadenoson produces hyperemia quickly and maintains it for a duration that is useful for radionuclide myocardial perfusion imaging. The selective nature of the drug makes it preferable to other stress agents such as adenosine, which are less selective and therefore cause more side-effects.Regadenoson has a 2 to 3 minute biological half-life.[1]