However, post-RP patients remain one of the most PDE-5 inhibitor refractory groups, with intercourse success rates of approximately 40% in placebo-controlled studies.18–20 An intact cavernous nerve-smooth muscle relationship is optimal for maximum PDE-5 effectiveness. Any reduction in the number of firing nerves or smooth muscle responsiveness decreases the Inhibitors,research,lifescience,medical effectiveness of the PDE-5 inhibitors. The responsiveness to PDE-5 inhibitors

after RP is clearly dependent on the time from surgery, with the maximum recovery taking place at 18 to 24 months,21 within the time frame expected for nerve recovery.22 That being the case, what rationale is there for the use of sildenafil in penile rehabilitation? Indeed, the early use of PDE-5 inhibitors has been questioned as providing little to no value.23 Inhibitors,research,lifescience,medical A randomized, placebo-controlled study of 76 men after bilateral NSRRP found serial NPT (1, 4, 8, and 12 months) and unassisted erectile function satisfactory for vaginal penetration at 1 year in men who took 50 or 100

mg of sildenafil citrate nightly for 9 months LDK378 postoperatively.19 The investigators found a 7-fold improvement in normalization of erectile function in the treatment group over placebo at 1 year. NPT was better in the treatment group, with most of the benefit demonstrated in the first 4 months and a profound loss of Rigi-Scan® Inhibitors,research,lifescience,medical (Timm Medical Technologies, Inc., Eden Prairie, MN)-detected Inhibitors,research,lifescience,medical NPT at 1 month postoperatively.17 The purported mechanisms to explain the results are reduction in postoperative corporal hypoxia enhanced endothelial function and possible neurotropic mechanisms. Montorsi and colleagues24 showed

in a placebo-controlled study that the use of sildenafil citrate taken nightly enhances NPT. It is possible that the nightly sildenafil citrate Inhibitors,research,lifescience,medical enhances corporal oxygenation in a suberectile state, much like PGE1 was shown to enhance corporal StO2. The administration of nightly sildenafil citrate was shown to decrease penile fibrosis in the human after RP.13 In patients in whom vascular endothelial function is impaired by conditions such as aging, diabetes, hypertension, or hyperlipidemia, administration of sildenafil citrate improved endothelium-dependent vasodilation.25–27 As endothelium-derived NO synthase (e-NOS) is important Edoxaban in the maintenance of erections, it is possible that sildenafil citrate is potentiating the pro-erectogenic effect of e-NOS. In rats treated within 24 hours of stroke, sildenafil citrate increased neurogenesis and reduced neurological deficits,28 suggesting the capacity to promote recovery of nerve function. Sildenafil citrate may be accelerating or enhancing cavernous nerve regeneration. Comparable studies have not been carried out with the other PDE-5 inhibitors.