This study to will compare the blood levels of sildenafil following administration of an experimental tablet vs. the conventional oral tablet.

Inclusion Criteria:

• Healthy males between the ages of 18 and 55 years.
• Body Mass Index of 18 to 30 kg/m2, and a total body weight >50 kg (110 lbs).

Exclusion Criteria:

• Smoking in excess of the equivalent of 5 cigarettes per day.
• Treatment with an experimental drug within 30 days or sildenafil, vardenafil, tadalfil within 4 days before first study dose.
• Develop blood pressure lowering or experience dizziness, lightheadedness when going from the laying down position to standing position.