 EHNA is also a very potent adenosine deaminase inhibitor with an IC50 ~2 nM.This dual inhibition would lead to the accumulation of the two inhibitory metabolites, adenosine  and cGMP, which may act in synergy to mediate diverse pharmacological responses including anti-viral, anti-tumour and anti-arrhythmic effects.Although EHNA potently inhibits adenosine deaminase, it has been successfully used with the proper controls as a tool to probe PDE2 functions.