TABLE 1.

Potency of well‐known PDE5 inhibitors. Potencies stated are IC50 values unless otherwise stated.

Drug name	Potency: PDE5i	Potency: other actions	References
Sildenafil	1–9 nM	PDE6: 10–40 nM	8 , 25 , 26 , 27 , 28
	KD 3.1 nM
Tadalafil	1–7 nM	PDE6: Ki 700 Nm PDE11: 10—300 nM	8 , 25 , 26 , 27 , 29 , 30
	KD 1.7 nM
	Ki 1.9 nM
Vardenafil	0.1‐1.0 nM	PDE1: 300 nM	8 , 25 , 26 , 29
	KD 0.32 nM	PDE6: Ki 0.3‐11 nM
	Ki 2.3 nM	PDE9: 680 nM
		PDE11: 240 nM
Udenafil	6–8 nM	PDE 1: 870 nM	31
		PDE 6: 50 nM
Dipyridamole	900–2000 nM	PDE6: 380–1000 nM	27 , 28 , 30
		PDE7: 1–2 μM
		PDE10: 1 μM
		PDE11: 800 nM
Zaprinast	50 nM–2.5 μM a	PDE6: 150 nM	27 , 28

^a Wide species and tissue dependence of zaprinast potency as a PDE5i.

Abbreviation: PDE, phosphodiesterase; PDE5i, phosphodiesterase‐5 inhibitor.