Hypertension

Inclusion Criteria

- Men and women aged 18 - 75 years
 - Essential hypertension not well controlled by current low dose (80 mg) valsartan monotherapy for at least 4 weeks. Patients on prior treatment with monotherapy diuretic, ACE-I or beta blocker or an ARB other  than valsartan and switched to the current low dose valsartan 80 mg monotherapy for at least 4 weeks are also eligible, provided the hypertension is still not well controlled.
 - Office systolic blood pressure (sitting) >140 mmHg (sitting for >/= 5 min., no cigarettes and/or coffee/tea for >/=30 min. before BP measurement).
 -  BMI <33 kg/m2

Exclusion Criteria

- Participation in any clinical investigational drug study within the previous 12 weeks 
 - Concomitant treatments with: 
1. Any anti-hypertensive treatment other than Valsartan 80 mg
2. Cytochrome P450-3A4 inhibitors or inducers 
3. Potassium-sparing diuretics
 - Severe hypertension (DBP >/= 110 mm Hg and/or SBP >/= 180 mm Hg) and/or evidence of secondary forms of hypertension  
 - Any of the following cardiovascular diseases:
 - History of cardiovascular shock
 - Myocardial infarction or unstable angina within the previous 6 months
 - Severe cardiac valve disease
 - Past or present severe rhythm or conduction disorder.
 - Cerebrovascular ischemic event and/or history of intracerebral hemorrhage or subarachnoid hemorrhage (SAH) within the previous 12 months
 - Type 1 or 2 diabetes mellitus
 - Proteinuria 
 - Uncorrected hypokalemia or hyperkalemia, sodium depletion and/or hypovolemia
 - Gastrointestinal disease resulting in the potential for malabsorption and/or severe gastro-intestinal tract narrowing; kock pouch (ileostomy after proctocolectomy)
 - Cholestasis or biliary obstruction
 - Liver disease or aspartate aminotransferase (AST) / alanine aminotransferase (ALT) levels >3 x upper limits of normal (ULN)
 - Renal failure, creatinine level >2.0 mg/dl