Study of udenafil daily in subjects with mild or no erectile dysfunction to evaluate effects on semen characteristics.

Safety Study in male subjects with no or mild ED (erectile dysfunction)

Inclusion Criteria:

• No or mild ED (erectile dysfunction) willing & able to provide 2 semen samples without the use of PDE-5 inhibitor or other excluded medication or devices on 2 separate days during screening and at Weeks 12 & 26
• BMI (body mass index) between 19 and 31 kilogram/meter squared

Exclusion Criteria:

• New onset coronary artery disease within last 3 months, history of myocardial infarction or cardiac surgical procedure within last 6 months or sudden cardiac arrest
• Nitrate medications for angina pectoris
• Used of anti-arrhythmic drug treatment or device
• Congestive heart failure
• Uncontrolled diabetes
• Stroke or transient ischemic attack (TIA) within last 6 months
• Bleeding disorder or history of GI bleeding within last 12 months
• Cancer chemotherapy
• History of alcohol or drug abuse