Intervention: Losartan
Trial phase: Phase 3
ATC code: C09CA01 | C09DA01 | C09DB06
SMILES: CCCCc1nc(Cl)c(CO)n1Cc1ccc(-c2ccccc2-c2nn[nH]n2)cc1
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 90
Group description: 50/100 mg Cozaar® (Losartan) administered orally once a day for 12 week period
Eligibility criteria:
Inclusion Criteria:

Subjects of both sex aged 18-75 inclusively.
Subjects who signed their written Informed Consent for participation in the study and willing to adhere to all Protocol procedures.
Subjects with documented diagnosis of grade I-II primary arterial hypertension within at least 3 months before screening.

Systolic blood pressure (SBP) (when seated) at Screening (Day -14)

For subjects administered with anti-hypertensive therapy: SBP ≤ 179 Hg
For subjects receiving no anti-hypertensive therapy (so called 'naïve' patients): 140≥SBP ≤179.
As per investigator's judgment, subjects with controlled arterial hypertension must benefit from the therapy switch to Kanarb (Fimasartan), manufactured by Boryung Pharmaceutical Co., Ltd, Republic of Korea, tablets 60/120 mg and Cozaar® (Losartan), manufactured by MERCK SHARP & DOHME B.V., Netherlands, .
For subjects administered with anti-hypertensive drugs: the anti-hypertensive drug may be safely cancelled during the "wash-out" period according to the investigator's judgment.
For women of child-bearing potential: negative urine pregnancy test at screening (Day -14). 8. Systolic blood pressure (SBP) (when seated) at Randomization (Day 0) ≥140 mmHg and ≤179 mmHg.

9. For women of child-bearing potential: negative urine pregnancy test at Randomization (Day 0)

Exclusion Criteria:

Grade III Arterial Hypertension.
Arterial hypotension (SPB ≤100 mm Hg) at Screening (Day -14) and/or Randomization (Day 0).
Subjects needing treatment with more than one anti-hypertensive drug (more than one active substance, including complex drugs).
Secondary (symptomatic) arterial hypertension.
Known bilateral renal arterial stenosis or unilateral renal arterial stenosis.
Hyperpotassemia >5,0 mmol/l (as per blood biochemistry results at Screening).
Primary hyperaldosteronism.
Known hypersensitivity to angiotensin-II receptors antagonists or any other study drug or comparator component.
Contraindications for use of angiotensin-II receptors antagonists.
Myocardial infarction and or unstable angina, and/or acute cerebrovascular accident/transient ischemic attack, and/or percutaneous coronary intervention, and/or coronary arterial bypass graft, acute coronary arteries involvement, and/or obliterative vascular atherosclerosis of low extremities, and/or grade III and IV retinopathy in anamnesis.
Clinically significant cardiac valves damage.
Cardiomyopathies
Chronic Heart failure (CHF) (except for CHF FC I NYHA).
Creatinine clearance less than 60 ml/min/1.73m2 calculated by Cockroft-Gault formula.
Known moderate to severe hepatic insufficiency and/or transaminase increase: AST and/or ALT ≥2*ULN.
History of infections (HIV, hepatitis B or C, syphilis).
Uncontrolled Diabetes mellitus, Glycosylated hemoglobin level (HbA1c) >7%.
Severe systemic diseases, such as gastro-intestinal tract diseases, autoimmune disorders, blood disorders and other conditions which may affect on the study drugs' absorption, distribution and and excretion.
Clinically significant abnormalities of laboratory parameters.
Drug or alcohol addiction, psychiatric disorders.
Medical history of oncological disease within 5 years before screening.
Subjects with biliary tracts obstruction.
Subjects with genetic disorders, such as galactose intolerance, congenital lactase insufficiency and glucose-galaclose malabsorption syndrome.
Any other acute disease or progression and/or decompensation at the moment of enrollment
Necessity to administer or administration of prohibited concomitant drugs from the "List of Prohibited Drugs" within 14 days before enrollment
Pregnancy or breast-feeding period; fertile women not using adequate contraception methods
Participation in another clinical trial within 3 months before Screening.
Other medical or psychiatric conditions or lab abnormalities that may increase potential risk associated with study participation and IP administration, or that may affect study results interpretation and as per investigator's judgment, make the subject ineligible.
Study site personnel or Sponsor's representatives immediately involved in the study.
Subjects, excluded from the study may not be included in it again.