Effects of adenosine A2A receptor low affinity agonist Regadenoson in patients with obstructive pulmonary disease, at risk for adenosine-induced bronchoconstriction mediated via A2B and/or A3 adenosine receptors.

Abstract

The pharmaceutical Regadenoson (Lexiscan TM ) Produced by Astellas Inc. Is currently in use as a pharmacological stress agent for myocardial perfusion imaging within the field of Nuclear Cardiology. Regadenoson is a selective A 2A adenosine receptor agonist, and also has a low affinity for adenosine receptors which cause bronchoconstriction in patients with reactive airways mediated via A 2B and A3 adenosine receptors. In a study of 42 patients with mild to moderate asthma and/or moderate to severe COPD who had a positive adenosine monophosphate test, Regadenoson proved to be relatively safe and well tolerated by most patients (90%). 8 Regadenoson is a low affinity agonist (Ki H 1.3 µM) for the A2A adenosine receptor, with at least 10-fold lower affinity for the A1 adenosine receptor (Ki > 16.5 µM), and weak, if any, affinity for the A2B and A3 adenosine receptors. 2,9 Activation of the A2A adenosine receptor by regadenoson produces coronary vasodilation 8 and increases coronary blood flow (CBF). It