Antoreb Mechanism of Action

Angiotensin II Receptor Blocker (ARB).
Pharmacology: Pharmacokinetics: Losartan is an oral, specific angiotensin-II receptor (type AT1) antagonist. Angiotensin II binds to the AT1 receptor, which is present in a variety of organs (including vascular smooth muscle, the adrenal gland, the kidneys, and the heart), and causes a number of biological effects. Smooth-muscle proliferation is also stimulated by angiotensin II. It binds exclusively to the AT1 receptor according to binding and pharmacological bioassays. Losartan and its pharmacologically active carboxylic acid metabolite (E-3174), regardless of the source or mechanism of synthesis, block all physiologically significant activities of angiotensin II in vitro and in vivo.
The removal of angiotensin II negative feedback on renin secretion after losartan therapy results in enhanced plasma renin activity. Angiotensin II levels in the blood rise as plasma renin activity rises. Antihypertensive action and decrease of plasma aldosterone levels are maintained despite these increases, demonstrating effective angiotensin II receptor blockage.
Losartan binds selectively to the AT1 receptor and does not bind to or block other hormone receptors or ion channels important in cardiovascular regulation.
Furthermore, losartan does not inhibit ACE (kininase II), the enzyme that degrades bradykinin. Consequently, effects not directly related to blocking the AT1 receptor, such as the potentiation of bradykinin-mediated effects, the generation of oedema (losartan 1.7%, placebo 1.9%) or fatigue (losartan 3.8%, placebo 3.9%), are not associated with losartan.
Losartan potassium significantly lowers proteinuria, fractional excretion of albumin, and IgG in non-diabetic hypertensive patients with proteinuria. Losartan keeps the glomerular filtration rate constant while lowering the filtration fraction. Losartan induces a reduction in serum uric acid (typically less than 24 micromol) that lasts throughout the treatment.
Losartan has no influence on autonomic reflexes or plasma noradrenalin levels over time. In patients with hypertension, losartan potassium at doses up to 150 mg once daily won't produce clinically significant changes in fasting triglycerides, total cholesterol, or HDL cholesterol. Losartan at the same doses had no effect on fasting glucose levels.