Usapa

Losartan is an angiotensin II receptor blocker (ARB) used to treat hypertension. Angiotensin-converting enzyme (ACE) inhibitors are used for a similar indication but are associated with a cough. When patients with ACE inhibitor associated coughs are switched to ARBs like losartan, they have an incidence of cough similar to placebo or hydrochlorothiazide. Losartan is available as losartan potassium oral tablets as well as a combination tablet of losartan potassium and hydrochlorothiazide. Patients taking losartan should have their renal function and potassium levels monitored.

Losartan is an angiotensin receptor blocker used to treat hypertension and diabetic nephropathy, and is used to reduce the risk of stroke.

Losartan is indicated to treat hypertension in patients older than 6 years, reduce the risk of stroke in patients with hypertension and left ventricular hypertrophy (though this benefit may not extend to patients with African heritage), and to treat diabetic nephropathy with elevated serum creatinine and proteinuria in patients with type 2 diabetes and hypertension. Losartan with hydrochlorothiazide is indicated to treat hypertension and to reduce the risk of stroke in patients with hypertension and left ventricular hypertrophy (though this benefit may not extend to patients with African heritage).

• Diabetic Nephropathy
• Heart Failure
• High Blood Pressure (Hypertension)
• Marfan Syndrome
• Stroke

Losartan is an angiotensin II receptor blocker used to treat hypertension, diabetic nephropathy, and to reduce the risk of stroke. Losartan has a long duration of action as it is given once daily. Patients taking losartan should be regularly monitored for hypotension, renal function, and potassium levels.

Losartan reversibly and competitively prevents angiotensin II binding to the AT₁ receptor in tissues like vascular smooth muscle and the adrenal gland. Losartan and its active metabolite bind the AT₁ receptor with 1000 times more affinity than they bind to the AT₂ receptor. The active metabolite of losartan is 10-40 times more potent by weight than unmetabolized losartan as an inhibitor of AT₁ and is a non-competitive inhibitor. Losartan's prevention of angiotensin II binding causes vascular smooth muscle relaxation, lowering blood pressure.

Angiotensin II would otherwise bind to the AT₁ receptor and induce vasoconstriction, raising blood pressure.

Losartan is approximately 33% orally bioavailable. Losartan has a T_max of 1 hour and the active metabolite has a T_max of 3-4 hours. Taking losartan with food decreases the C_max but does only results in a 10% decrease in the AUC of losartan and its active metabolite. A 50-80mg oral dose of losartan leads to a C_max of 200-250ng/mL.

The volume of distribution of losartan is 34.4±17.9L and 10.3±1.1L for the active metabolite (E-3174).

Losartan is 98.6-98.8% protein bound and the active metabolite (E-3174) is 99.7% protein bound in serum.

A single oral dose of losartan leads to 4% recovery in the urine as unchanged losartan, 6% in the urine as the active metabolite. Oral radiolabelled losartan is 35% recovered in urine and 60% in feces. Intravenous radiolabelled losartan is 45% recovered in urine and 50% in feces.

The terminal elimination half life of losartan is 1.5-2.5 hours while the active metabolite has a half life of 6-9 hours.

Losartan has a total plasma clearance of 600mL/min and a renal clearance of 75mL/min. E-3174, the active metabolite, has a total plasma clearance of 50mL/min and a renal clearance of 25mL/min.

The oral TDLO in mice is 1000mg/kg and in rats is 2000mg/kg. In humans the TDLO for men is 10mg/kg/2W and for women is 1mg/kg/1D.

Symptoms of overdose are likely to include hypotension, tachycardia, or bradycardia due to vagal stimulation. Supportive treatment should be instituted for symptomatic hypotension. Hemodialysis will not remove losartan or its active metabolite due to their high rates of protein binding.

• Take at the same time every day.
• Take with or without food. Food delays absorption, but does not affect the extent of absorption.