5-[2-Ethoxy-5-(4-ethylpiperazin-1-ylsulfonyl)pyridin-3-yl]-3-ethyl-2-(2-methoxyethyl)-2,6-dihydro-7H-pyrazolo[4,3-d]pyrimidin-7-one

Gisadenafil (UK-369003) is a specific, orally active phosphodiesterase 5 (PDE5) inhibitor with an IC50 of 3.6 nM and prevents degradation of cyclic guanosine monophosphate (cGMP)[1].

PDE5A: 3.6 nM (IC₅₀); PDE1A: 9.1 μM (IC₅₀)

[1] Silva J, et al. Transient hypercapnia reveals an underlying cerebrovascular pathology in a murine model for HIV-1 associated neuroinflammation: role of NO-cGMP signaling and normalization by inhibition of cyclic nucleotide phosphodiesterase-5. J Neuroinflammation. 2012 Nov 20;9:253. DOI:10.1186/1742-2094-9-253
[2] Rawson DJ, et al. The discovery of UK-369003, a novel PDE5 inhibitor with the potential for oral bioavailability and dose-proportional pharmacokinetics. Bioorg Med Chem. 2012 Jan 1;20(1):498-509. DOI:10.1016/j.bmc.2011.10.022