Hypertension

Inclusion Criteria

-Subjects are eligible to be included in the study only if they meet all of the following criteria:
 - Aged 18 years or older, but less than 65 years;
 - Either male or female
 - BP is uncontrolled after at least 4 weeks of prior antihypertensive mono-therapy (the dosage of mono-therapy should be the starting dose of an angiotensin receptor blocker (ARB), angiotensin converting enzyme inhibitor (ACEI), b-blocker (BB), calcium channel blocker (CCB), or diuretic) both in the beginning and at the end of the screening period (uncontrolled BP is defined as MSSBP ≥140 and <160mmHg and/or MSDBP ≥ 90 and <100mmHg, and in the presence of diabetes mellitus: MSSBP ≥130 and <160mmHg and/or MSDBP ≥80 and <100mmHg);

Exclusion Criteria

- Subjects meeting any of the following criteria are to be excluded from the study:
 - Known hypersensitivity to nifedipine or to any of the following excipients, hypromellose, polyethylene oxide, magnesium stearate, sodium chloride, iron oxide red (E172/C.I.77491), cellulose acetate, polyethylene glycol 3350, hydroxypropyl cellulose, propylene glycol, titanium dioxide (E171/C.I.77891)
 - Evidence of secondary hypertension such as coarctation of the aorta, pheochromocytoma, hyperaldosteronism, etc.
Severe gastro-intestinal tract narrowing; gastric banding; kock pouch (ileostomy after proctocolectomy)
 - Evidence of cardiovascular shock
 - Pregnant, possibly pregnant, planning to become pregnant or lactating women
 Received combination (two or more than two drugs combination) therapy or higher dosage (a higher dosage is defined as a higher dosage than the standard recommended starting dosage presented in the label of each drug) mono-therapy in the beginning or at the ending of the screening period.
 - History of  cerebrovascular ischemic event (stroke or transient ischemic attack [TIA]) within 6 months
 - History of intracerebral hemorrhage or subarachnoid hemorrhage
 - History of hypertensive retinopathy 
 - Any history of heart failure, New York Heart Association (NYHA) classification III or IV
Severe coronary heart disease as manifested by a history of myocardial infarction or unstable angina in the past 12 months or a history of percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG)
 - Clinically significant cardiac valvular disease
 - History of arrhythmia
 - Type 1 diabetes mellitus (DM) 
 - Hyperkalemia history: a serum potassium level above the upper limit of normal in the laboratory range;
 - Liver disease or aspartate transaminase (AST) or alanine transaminase (ALT) levels >3 x upper limit of normal (ULN)
 - Renal insufficiency, defined as estimated glomerular filtration rate (eGFR) of <30 mL/min, or on hemodialysis