Efficacy and Tolerability Study of Avanafil in Russia

Primary Objective: o To assess the change in percent of sexual attempts in which subjects are able to maintain an erection of sufficient duration to have successful intercourse between the run-in period and treatment period: * The change in percent of sexual attempts in which subjects are able to insert the penis into the partner's vagina. * The change in score on the erectile function (EF) domain of the International Index of Erectile Function (IIEF) questionnaire. Secondary Objective: o To evaluate the safety and tolerability of avanafil in patients with erectile dysfunction (ED).