Phase IIIb, randomized, double-blind, prospective, multicenter study to evaluate the efficacy and safety of the fixed-dose combination of losartan / chlorthalidone compared with losartan / hydrochlorothiazide in the treatment of patients with essential arterial hypertension.

Two groups of patients will be formed, who wil start treatment with the lower dose (Losartan 50 mg + chlorthalidone 12.5 mg; Losartan 50 mg + hydrochlorothiazide 12.5 mg).

Blood pressure (BP) figures will be evaluated and, in those patients who do not reach the therapeutic goal, defined as a decrease in Systolic blood pressure (SBP) / Diastolic blood pressure (DBP) values of 20/10 mmHg with respect to their baseline values or BP <140 / 90 mmHg, the dose will be escalated to the next available concentration for both treatments (Losartan 100 mg + chlorthalidone 25 mg; Losartan 100 mg + hydrochlorothiazide 25 mg) at 30 days or during an unscheduled visit.

After two months of treatment, the BP figures obtained with the final dose and the proportion of subjects who achieved a decrease in SBP / DBP values of 20/10 mmHg or <140/90 mmHg with respect to both combinations will be compared, and the frequency of adverse events presented will be described.

Inclusion Criteria:

• Any sex.
• That they agree to participate in the study and give their informed consent in writing.
• Age between 18 and 65 years old at the beginning of the study.
• Patients with essential arterial hypertension with BP ≥140 / 90 mmHg and <180/110 mmHg.
• Women of childbearing potential using a contraceptive method (barrier, oral hormonal, injectable, subdermal), menopausal or surgically sterile.

Exclusion Criteria:

• The drug is contraindicated for medical reasons.
• Glomerular filtration rate ≤30 ml / min x 1.73 m2.
• Hypersensitivity to any of the components of the formula or other sulfonamides.
• Patients treated with other diuretics.
• Patient with a history of vascular disease (cerebrovascular disease, acute coronary syndrome, etc.) and acute renal failure in the last 6 months.
• Patient with severe complications of type 2 diabetes mellitus (Ketoacidosis or hyperosmolar nonketotic coma).
• Patients participating in another clinical study involving an investigational treatment or participated in one in the previous 4 weeks.
• Positive pregnancy test, women who are pregnant, breastfeeding or planning a pregnancy while conducting the study.
• Oncological patients (except basal cell skin cancer) or with serious diseases that, in the opinion of the investigator, have a serious prognosis or a life expectancy of less than 1 year, as well as mental illnesses.
• Patients diagnosed with gout.
• Patients whose participation in the study may be influenced (employment relationship with the research center or sponsor, inmates, etc.).