Comparing Safety and Efficacy of Amlodipine Verses S Amlodipine in Patients With Essential Hypertension

1. Clinical Study Design \- In this clinical study, Part 1 is conducted as a preliminary study on 10 subjects at a single center, and based on the results of Part 1, the sponsor and the principal investigator determine whether to proceed with Part 2. With Part 2 as the multicenter main study conducted on the remaining 70 subjects, 80 subjects in total have been planned for Part 1 and Part 2. 2. Interim analysis \- The interim analysis is conducted when the study on 10 subjects at a Part 1 single center has been completed; the analysis is made on all endpoints planned for this clinical study. 3. Clinical study methods - During screening, subjects who have voluntarily signed the Informed Consent Form are tested for eligibility to this clinical study. After a wash-out period of at least two weeks, subjects who satisfy the inclusion/exclusion criteria are randomly assigned to two groups (S-amlodipine group, Amlodipine group). Thereafter, the subjects are enrolled and orally administered with the investigational product once a day for 12 weeks, during which they receive a total of five visits for tests conducted for assessment of efficacy and safety. (In case of confirmed eligibility without administration of contraindications, the wash-out period may be omitted and Visits 1 and 2 may be paid on the same day)