Inclusion criteria:
Healthy subjects (male) between 20 – 45 years of age and Body Mass Index (BMI) within 15% of normal range according to the accepted normal values between 18.5 and 30 (inclusive), calculated as kg/m2.
Subjects with no significant diseases or clinically significant abnormal findings in laboratory evaluations.
Subjects with normal vital signs.
Subjects who agree with patient consent form.
Exclusion criteria:
Allergic reaction to sildenafil
Acute or chronic diseases of the cardiovascular, bronchopulmonary, neuroendocrine systems, and also diseases of the gastrointestinal tract, liver, kidneys and blood, eye disease
The presence of mental disorders, including a history. Dehydration due to diarrhea, vomiting or other reason within the last 24 hours before taking the drug
Consumption of nitric oxide donor drugs, organic nitrates or other nitrite forms during the 30 days before drug administration in study period I.
Systolic blood pressure (SBP) <100 mm Hg or ≥ 130 mm Hg
Diastolic blood pressure (DBP) <60 mm Hg or ≥ 85 mm Hg.
Smoking more than 10 cigarettes per day and could not tolerate cigarette cessation during each clinical period;
Subjects who has used any drug including prescription or Over-The-Counter (OTC) drugs within 1 days prior to the start of the study and might need drug intake during study period;
History of alcohol or drug abuse within 2 years before the start of the study;
Heavy drinker of caffeine, grapefruit juice or caffeinated drinks or who are on special diet (such as vegetarians) or do exertional physical activity;
A history of difficulty with donating blood or donation of more than 500 ml blood within 7 days prior to the start of the study.