Effects of Sildenafil on Penile Vascular Function in Hypertensive Men With Erectile Dysfunction

Vasculogenic erectile dysfunction (ED) is a highly prevalent health problem that is directly related with increased cardiovascular risk. In this context, phosphodiesterase type 5 inhibitors (PDE5 inhibitors) are indicated in the treatment of ED because these drugs increase bioavailability of the endothelial-dependent potent vasodilator nitric oxide. Thus, these drugs could also induce a reduction in arterial pressure and improve microvascular endothelial function in hypertensive patients. The primary aim of the study is to investigate the acute and chronic effects of sildenafil citrate (®Viagra) on penile and systemic microvascular function of hypertensive patients presenting with ED. The secondary aim is to evaluate the effects of the treatment on arterial pressure. The study design is a prospective 2 x 2 cross-over, randomized, double blind clinical trial that will include 75 sexually active hypertensive men (age between 50-70 years) under anti-hypertensive treatment (arterial pressure \< 160/100 mmHg) presenting with ED. Erectile function will be evaluated using the International Index of Erectile Function (IIEF-5) questionnaire. Patients with non-vasculogenic ED or diabetes will be excluded from the study. Forty-five age-matched healthy subjects will be included as a comparator group. The evaluation of systemic microvascular function will be performed in the skin of the forearm and penile microvascular function in the skin of the base of the penis using the non-invasive methodology of laser speckle flowmetry coupled to cutaneous iontophoresis of a vasodilator (acetylcholine). In the acute protocol, microvascular evaluation will be carried out before and one hour after the oral administration of 100 mg of sildenafil citrate. In the chronic protocol, only hypertensive men will be randomized to receive either or placebo sildenafil 50 mg twice daily for 30 days. After a 30-day washout period the patients will receive the complementary treatment. The evaluation of penile and systemic microvascular function, as well as ambulatory blood pressure monitoring, will be performed before randomization and in the end of each treatment period.