OR-1896 is the active metabolite of Levosimendan, a highly specific phosphodiesterase (PDE III) inhibitor, a vasodilator with partial anti-inflammatory properties that produces vasodilation in different types of blood vessels through activation of ATP-sensitive (KATP) and other potassium channels.OR-1896 can be used to study heart failure and vascular dysfunction. OR-1896 can be used to study heart failure and vascular dysfunction.

EMD57439 is a selective PDE-III inhibitor, showing no significant increase in c-AMP concentration and producing little change in Ca(50).

Quercetin 3-O-methyl ether is a potent phosphodiesterase (PDE)3/4 inhibitor, it has potential for treating asthma against ovalbumin-induced airway hyperresponsiveness.

Arofylline (LAS 31025) is a PDE4 inhibitor and can be used for asthma studies.

Gisadenafil (UK-369003) is a selective inhibitor of phosphodiesterase 5 (PDE5) with an IC50 of 3.6 nM and prevents degradation of cGMP.