Losartan potassium is an angiotensin II receptor antagonist with antihypertensive activity due mainly to selective blockade of AT1 receptors and the consequent reduced pressure effect of angiotensin II.
Angiotensin II receptor antagonist.
Pharmacokinetics: Losartan potassium is readily absorbed from the GIT following oral administration with an oral bioavailability of about 33%. Losartan potassium undergoes first-pass metabolism to form an active carboxylic acid metabolite E-3174 (EXP-3174), which has greater pharmacological activity than losartan and some inactive metabolites. Metabolism is primarily by cytochrome P-450 isoenzymes CYP2C9 and CYP3A4. Peak plasma concentrations of losartan and E-3174 occur about 1 hr and 3-4 hrs, respectively, after an oral dose. Both losartan and E-3174 are >98% bound to plasma proteins. Losartan is excreted in the urine and in the feces via bile as unchanged drug and metabolites. Following oral dosing, about 35% of the dose is excreted in the urine and about 60% in the feces. The terminal elimination t½ of losartan and E-3174 are about 1.5-2.5 hrs and 3-9 hrs, respectively.
Management of hypertension. May have a role in patients who develop cough with ACE inhibitors.
Usual Dose: 50 mg once daily.
The dose may be increased, if necessary, to 100 mg daily as a single dose or 2 divided doses.
Elderly >75 years, Patients with Moderate to Severe Renal Impairment (CrCl <20 mL/min) or Intravascular Fluid Depletion: Initial Dose: 25 mg once daily.
Losartan potassium should be used with caution in patients with renal artery stenosis. Reduced doses may be required in patients with renal or hepatic impairment. Patients with volume depletion may experience hypotension.
Use in lactation: Losartan potassium should be used with care, if at all, during breastfeeding.
Use in Pregnancy: Losartan potassium is contraindicated in pregnancy.
Use in Lactation: Losartan potassium should be used with care, if at all, during breastfeeding.
Adverse effects include dizziness and dose-related orthostatic hypotension. Hypotension may occur particularly in patients with volume depletion (eg, those who have received high-dose diuretics). Losartan potassium may cause hyperkalemia in patients with renal disease. Other adverse effects that have been reported with angiotensin II receptor antagonists include respiratory tract disorders, back pain, GI disturbances, fatigue and neutropenia.
Store at temperatures not exceeding 30°C.
C09CA01 - losartan ; Belongs to the class of angiotensin II receptor blockers (ARBs). Used in the treatment of cardiovascular disease.