Efficacy and Safety of Fimasartan Alone or Combined With HCTZ in Mexican Patients With Essential Hypertension

Inclusion Criteria: * Ability to understand the study subject information and to voluntarily grant their informed consent. * Men or women, 18 to 70 years old. * With grade 1 or 2 essential arterial hypertension based on a sitting diastolic blood pressure (DBP) ≥90 mmHg and ≤109 mmHg (MEXICAN OFFICIAL NORM 030-SSA). * Trustworthiness and willingness to attend all the study follow-up visits , according to the investigator's judgment. * Patients already on antihypertensive therapy, not adequately controlled and that, according to the investigator's judgment, could be safely submitted to a two-week washout period. Exclusion Criteria: * Severe hypertension (Grade 3), with SBP≥180 mmHg and/or DBP≥110 mmHg, according to OFFICIAL MEXICAN NORM NOM 030-SSA criteria. * Secondary hypertension. * Impossibility to safely undergo a two week washout period from previous treatment prior to assignment to the study treatment, if applicable and according to the principal investigator´s judgment. * Systemic diseases such as renal dysfunction (creatinine ≥1.5 time above the upper limit of the reference range), gastrointestinal disorders, hematological disorders or liver dysfunction (AST y/o ALT ≥1.5 times the upper limit of the reference range), capable to affect the absorption, distribution, metabolism and excretion of the study drug. * Non-controlled diabetes mellitus (HbA1c\>9%) * Morbid obesity (BMI≥40 kg/m2) * Myocardial infarction or severe coronary artery disease or clinically significant congestive heart failure, within the six months prior to the screening visit. * Auto-immune or connective tissue disease. * Evidence in the medical record of serious infectious diseases such as hepatitis type B or C or a positive HIV test at screening. * Clinically significant laboratory test abnormalities, according to the investigator's judgment. * Concomitant treatment which might affect blood pressure values. * Known allergies or contraindication to the use of angiotensin II receptor antagonists. * Pregnancy, breastfeeding or in the case of women with childbearing potential, the rejection to use an effective contraceptive method, according to the investigator's judgment. * History of alcohol or addictive substance abuse. * Subjects participating in other clinical studies or who have participated in other study within the 6 months prior to screening. * Any other reason which in the investigator's opinion might contraindicate the participation of a subject in the study.