Two inhaled, selective AR ligands with anti-inflammatory actions, i.e., A2AAR agonist UK432097 16 (for COPD) and mixed A2AAR agonist/A3AR antagonist GW328267X 17 (for asthma and allergic rhinitis) failed to show efficacy in clinical trials, but there were complicating pharmacokinetic factors (Mantell et al., 2010). Here, AR is linked to chronic obstructive pulmonary disease.