The investigators want to find out if a treatment with a new combination of two different antihypertensive drugs (olmesartan and amlodipine) in one tablet in patients with moderately elevated blood pressure is more effective than treatment with just one substance (candesartan). All antihypertensive treatment will be ceased for two weeks to achieve comparable baseline conditions. Treatment is then started with the single substance. After six weeks, therapy is changed to another single substance and after a further six weeks, to the fixed combination tablet. Blood pressure is determined by office measurements taken by the doctor and via long-term ambulatory blood pressure monitoring (ABPM). Participants may be male or female and must be over 18 years of age.

SEVICONTROL-2:

Efficacy and Safety of a sequential therapy change from Candesartan 32 mg to the fixed combination of olmesartan 40 mg/amlodipine 10 mg in patients with poorly controlled moderate hypertension - an open phase IV trial

Inclusion Criteria:

• male or female patients >= 18 years of age
• essential hypertension, i. e. systolic office bp >= 140 mmHg for pre-treated patients or >= 160 mmHg for untreated patients at screening visit and >= 160 mmHg at end of wash-out
• signed IC

Exclusion Criteria:

• systolic office bp > 180 mm Hg at screening visit
• known hypertensive retinopathy GIII or IV
• recent (< 4 weeks ago) myocardial infarction or indication for coronary or peripheral revascularisation
• type I diabetes or poorly controlled (HbA1c >= 8) type II diabetes
• chronic heart failure NYHA III or IV
• prior stroke or TIA
• creatinine clearance < 60 ml/min or condition after kidney transplant
• moderately or severely impaired liver function (ALT or AST or bilirubin more than double normal value)
• women of childbearing potential without highly effective contraception, pregnant or breastfeeding women
• concomitant therapy with lithium
• hemodynamically relevant mitral or aortic valve stenosis (>= II°) or hypertrophic obstructive cardiomyopathy
• concomitant therapy with strong CYP3A4 inhibitors or inductors
• african patients
• concomitant severe psychiatric condition that might impair proper intake of study medication
• life expectancy < 6 months
• night shift workers
• known other mandatory indication for treatment with antihypertensive medications
• parallel participation in other clinical trials