The principal scientific objective of the trial is to identify the factors that are associated with differential blood pressure responses between drugs. This may allow investigators to produce new hypotheses on the pathophysiology of hypertension and on the mechanisms of drug action.

These factors can be of different types:

• Environmental factors (sodium or alcohol intake);
• Morphological (height, weight, body mass index, body surface area);
• Initial blood pressure;
• Electrocardiogram (ECG) parameters of left ventricular hypertrophy;
• Biological parameters as the activity level of the renin angiotensin aldosterone system;
• Genetic polymorphisms.

Inclusion Criteria:

• Participants have to be 25 to 60 years of age
• Both genders
• Systolic blood pressure of 140 mmHg or above; diastolic blood pressure of 90 mmHg or above.
• Cardiovascular risk must not be high, to allow for two periods of 4 weeks of placebo without ethical concern.