(R)-(-)-Rolipram is a potent and cAMP-specific PDE4 inhibitor with IC50 of 0.22 uM; 2.5-fold more potent than (+)-rolipram (IC50= 2.58 uM) in inhibiting membrane-bound PDE 4.

(S)-(+)-Rolipram is a PDE4-inhibitor and an anti-inflammatory agent, less potent than its R enantiomer.

A highly potent, selective, brain-penetrating and orally active phosphodiesterase 2A (PDE2A) inhibitor with IC50 of 0.61 nM.

A novel bifunctional PDE4 inhibitor (IC50=5 nM) and long acting β2-adrenoceptor agonist (EC50=8 nM).

A novel potent, selective PDE5 inhibitor with IC50 of 0.056 nM for PDE5A1.

A novel potent, selective PDE9A inhibitor with IC50 of 11 nM, >45-fold selectivity over other PDE isoforms.

A novel potent, selective, brain-penetrable and orally active PDE2A inhibitor with IC50 of 1.5 and 4.2 nM for human and rat PDE2A, respectively.

A potent, selective, brain penetrant PDE9A inhibitor with IC50 of 1.8 nM.

AMG 580 (AMG580) is a novel potent, selective phosphodiesterase 10A (PDE10A) inhibitor with IC50 of 0.13 nM.

AMG-579 is a potent, selective, CNS penetrant, orally bioavailable PDE10A inhibitor with IC50 of 0.1 nM.

AN-2728 is a topically administered, boron-containing, anti-inflammatory compound that inhibits PDE4 activity and thereby suppresses the release of TNFalpha, IL-12, IL-23 and other cytokines.

Apremilast(CC10004) is a novel small molecule inhibitor of PDE4 with an IC50 value of 74 nM.

Avanafil(TA-1790) is a potent and highly selective phosphodiesterase-5(PDE-5) inhibitor(IC50=5.2 nM) for erectile dysfunction; lower selectivity against PDE1, PDE6, and PDE11.

Bay 60-7550 is a potent PDE2 inhibitor with IC50 values of 2.0 nM (bovine) and 4.7 nM (human); 50-fold more selective for PDE2 compared to PDE1 and greater than 100-fold selective compared to PDE5, PDE3B, PDE4B, PDE7B, PDE8A, PDE9A, PDE10A, and PDE11A.

BI 409306 is an inhibitor of phosphodisterase 9A（PDE9A）.

BW-A 78U is a PDE4 inhibitor with an IC50 of 3 μM.

Cilastazol is a 2-oxo-quinoline with vasodilator, antimitogenic, antithrombotic, and cardiotonic properties. This compound has been shown to cause inhibition of adenosine uptake, eventually resulting in changes to cAMP levels. Studies have shown Cilostazo

Cilomilast(SB 207499; Ariflo) is a potent PDE4 inhibitor with IC50 of about 110 nM, has anti-inflammatory activity and low central nervous system activity.

Deltarasin is a novel and small molecule inhibitor which can inhibit the KRAS-PDEδ interaction(Kd= 41 nM. binding to PDEδ) and impairs oncogenic KRAS signalling.

E6005 potently and selectively inhibited human PDE4 activity with an IC50 of 2.8 nM and suppressed the production of various cytokines from human lymphocytes and monocytes with IC50 values ranging from 0.49 to 3.1 nM.

GSK256066 is a selective PDE4B(equal affinity to isoforms A-D) inhibitor with IC50 of 3.2 pM, >380,000-fold selectivity versus PDE1/2/3/5/6 and >2500-fold selectivity against PDE4B versus PDE7.

IBMX(NSC165960; SC2964) is a competitive nonselective PDEs inhibitor with IC50 of 2-50 uM but does not inhibit PDE8 or PDE9; nonselective adenosine receptor antagonist.