QEQ Treatment Responsiveness Evaluation Study

Inclusion Criteria

• •Subjects must have documented clinical diagnosis of erectile dysfunction based on a screening SHI-M score of \<21 and the subject fulfilling the NIH definition of erectile dysfunction
• •Subjects must be either PDE-5 inhibitor naive; i.e. have never used sildenafil, tadalafil or vardenafil, or have been previously treated with no more than six doses of a PDE-5 inhibitor (sildenafil, tadalafil, vardenafil) and must have taken their last dose no less than 4 weeks prior to the screening visit