Question: how does pde5 inhibitor work?
Answer: PDE5 inhibitors are similar in structure to cGMP; they competitively bind to PDE5 and inhibit cGMP hydrolysis, thus enhancing the effects of NO. This increase in cGMP in the smooth muscle cells is responsible for prolonging an erection. PDE5 inhibitors lack a direct effect on corpus cavernosum smooth-muscle relaxation.