PDE5-IN-13 (Compound 14b)inhibits phosphodiesterase 5 (PDE5A) with an IC 50 of 3 nM. PDE5-IN-13 is a potential candidate for PAH (pulmonary arterial hypertension) research. PDE5-IN-13 has high selectivity for targets over PDE1 , PDE2 , PDE3 , PDE4 , PDE7 , PDE8 , PDE9 , PDE10 , and PDE11. PDE5-IN-13 is orally active.