Telmisartan With or Without Hydrochlorothiazide (HCTZ) Compared With Losartan With or Without HCTZ in Mild to Moderate Hypertensive Patients

Inclusion Criteria: * Age ≥ 18 years * Mild-to-moderate essential hypertension defined as a mean diastolic blood pressure (DBP) ≥ 95 mmHg and \< 110 mmHg and systolic blood pressure (SBP) \< 180 mmHg measured by manual cuff sphygmomanometer at the end of the wash-out period * Written informed consent Exclusion Criteria: * Nursing, pregnancy or childbearing potential women, post-menopausal women will be enrolled with last menstruation \> 1 year prior to start wash-out phase or surgically sterile * Secondary hypertension * Malignant hypertension (retinal haemorrhage, exudates or papillary oedema) * Clinically significant sodium depletion as defined by serum sodium level \< 130 mEq/L and/or clinically significant hyperkaliemia as defined by serum potassium level \> 5.5 mEq/L or clinically significant hypokaliemia as defined by serum potassium level \< 3.0 mEq/L * Atrial fibrillation or frequent ventricular ectopic beats or other arrhythmias which, in the investigator opinion could compromise patient's participation to the trial * Congestive heart failure (CHF) (NYHA (New York Heart Association) functional class CHF III-IV) * Angina pectoris or myocardial infarction * Cardiac surgery within the past 3 months prior to start the wash-out period * Stroke within the past 6 months prior to start the wash-out period * Renal insufficiency defined as creatininaemia \> 2mg/dl * Bilateral renal artery stenosis, renal artery stenosis in a solitary kidney, post renal transplant, presence of only one functioning kidney * Liver insufficiency, defined as bilirubinaemia \> 2mg/dl and AST (aspartate aminotransferase) or ALT (alanine-aminotransferase) \> twice the upper normal range * Clinically significant metabolic and endocrine disease * Autoimmune disease * Previous history of angioedema * Body mass index \> 30kg/m2 * Arm circumference \> 32 cm * Any condition that may be likely to compromise patients participation to the trial (alcohol or drug abuse, disability illness, etc.) * Concomitant therapy with antihypertensive drugs non permitted by protocol, corticosteroids or drugs known to affect blood pressure * Concomitant use of lithium or cholestyramine or colestipol resins (potential drug interactions with HCTZ) * Investigational drug treatment within the past 30 days before the enrolment or concurrent participation to any other trial * Sensitivity, significant adverse reaction or contraindications to the study drugs (telmisartan, losartan, HCTZ) * Predictable lack of patient co-operation