Cas number:  224785-91-5 Molecular Formula：C23H33ClN6O4S

was the second agent to be marketed and had the advantage that its onset time was not reduced by taking the medication on a full stomach . It is 30 times more potent as an inhibitor of PDE5 (mean IC50, 3.9 nM) than sildenafil and 10 times more potent than tadalafil, with a greater selectivity (>1,000 times) for human PDE5 than for human PDE2, PDE3, and PDE4 and moderate selectivity (>80 times) for PDE1. The PDE inhibitory selectivity and both the in vitro and in vivo potency of the new PDE5 inhibitor. specifically inhibited the hydrolysis of cGMP by PDE5, with an IC50 of 0.7 nM (sildenafil 6.6 nM). The IC50 of for PDE1 was 180 nM, for PDE6 11 nM, and for PDE2, PDE3 and PDE4 more than 1,000 nM.