Difficulty in enrolling subjects

The purpose of this study is to evaluate the effect of a third-generation Calcium Channel Blocker (CCB), manidipine, compared with second-generation Calcium Channel Blocker (CCB), amlodipine, on the development of peripheral edema using Direct Segmental Multi-Frequency Bioelectrical Impedance Analysis (DSM-BIA) method in patients with mild to moderate essential hypertension. Investigator expects this study could show more objective evidence of better safety of manidipine compared with amlodipine for peripheral edema.

Dihydropyridine Calcium Channel Blockers (CCBs) are one of the most commonly used potent antihypertensive agents. Their vasodilatory effects are associated with Adverse Effects (AEs) such as peripheral edema, headache and flushing.

The incidence of peripheral edema with Calcium Channel Blocker (CCB) is 6% in a recent systematic review and is clearly dose-dependent and more common in women, in obese and in elderly hypertensives. Peripheral edema could be a cause for poor persistence with therapy or antihypertensive treatment withdrawal and has a deleterious impact on health-related quality of life.

A recent meta-analysis of head-to-head trials to compare the efficacy and safety profile of manidipine and amlodipine showed significantly better safety of manidipine: the Relative Risk (RR) for adverse event was 0.69 (0.56-0.85), and particularly for ankle edema Relative Risk (RR) was 0.35 (0.22-0.54).

Although peripheral edema is an important issue in Calcium Channel Blocker (CCB) treatment, techniques (e.g, ankle-foot volume using a water displacement measurement, plethysmography, and pretibial subcutaneous tissue pressure) for the objective measurement are not generally available in a clinical setting. Most clinical studies relied on self-report of peripheral edema that is not a reliable objective method.

Recently, Bioelectrical Impedance Analysis (BIA) has become increasingly popular for estimating body composition, including Extracellular Water (ECW) and Intracellular Water (ICW), fat mass and fat-free mass. Mechanistically, the Calcium Channel Blocker (CCB)-related peripheral edema is likely due to distal arteriolar dilatation with capillary leak to tissue spaces. Because BIA method can measure the edema as the ratio of Extracellular Water (ECW) to Total Body Water (TBW), it may reflect the Calcium Channel Blocker (CCB)-related edema. Moreover, the Direct Segmental Multi-frequency Bioelectrical Impedance Analysis (DSM-BIA) has been validated to assess segmental body (i.e., trunk, arms and legs) composition in addition to total body composition and can provide segmental edema score as well as total edema score. This new, previously not reported method is expected to provide more objective and precise data for peripheral edema.

Inclusion Criteria:

• Male and female outpatients between the ages of 20 and 80 years with uncomplicated essential hypertension are eligible.
• Inclusion criteria requires that patients have either stage I or stage II hypertension (mean sitting systolic Blood Pressure (BP) 140-179 mmHg, diastolic BP 90-109 mmHg).
• The patients are newly diagnosed or known hypertensive subjects who were not taking antihypertensive agents for more than the last 4 weeks.

Exclusion Criteria:

• Patients are excluded from the study if they have any evidence of clinically significant concurrent medical conditions including cardiac, renal, hepatic, gastrointestinal, or endocrinologic disease.
• Patients are also excluded if they have known hypersensitivity or serious drug reactions to Calcium Channel Blockers (CCBs), any evidence of prior deep vein thrombosis, lymphatic disease, or concurrent requirement for medications that could affect Blood Pressure (BP) or salt and water retention (e.g, nonsteroidal antinflammatory drugs, estrogen containing drugs).

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