AR and asthma: Approved AR drugs include adenosine for paroxysmal supraventricular tachycardia (A1AR agonism), adenosine and regadenoson for myocardial perfusion imaging (A2AAR agonism, causing coronary artery vasodilation [4]), istradefylline for Parkinson’s disease (A2AAR antagonism [5]), and the nonselective AR antagonist theophylline for asthma.