To assess the pharmacodynamic effects of co-administrated SK3530 (PDE5 inhibitor) and Amlodipine, phase I study in Hypertensive patient was designed.

Inclusion Criteria:

• Male subjects 19-65 years of age inclusive
• Subjects with hypertension as defined 100 mmHg ≤ SBP<140 mmHg and 65 mmHg ≤ DBP < 90 mmHg after more than 5 minutes in the supine position
• Written informed consent
• Willing and able to comply with the requirements of the protocol

Exclusion Criteria:

• Subjects with acute or chronic disease within 4 weeks of study initiation.
• Subejcts with any gastrointestinal disorders known to alter drug absorption(except appendectomy, herniotomy, etc.)
• Subjects with any clinically significant allergic disease or with a known allergy to the PDE5 inhibitors
• Subjects with clinically significant abnormalities on laboratory tests
• Subjects with orthostatic hypotension defined as a fall in systolic blood pressure of at least 20 mmHg or diastolic blood pressure of at least 10 mmHg when a person assumes a standing position
• Subjects with abnormal QTc interval(≥440ms)
• Subjects with color-blindness or weakness
• Subejcts with alcohol, drug or caffeine abuse
• Diet known to alter drug absorption, distribution, metabolism or elimination processes
• Subjects who participated in other clinical studies within 2 months before an administration
• Other subjects who are ineligible for the study at the discretion of the principle investigator or sub-investigators

about 6 weeks

Screening visit ~ Post-study visit