Losartan
Also known as: Cozaar, losartan potassium, ARB, angiotensin receptor blocker
Losartan (Cozaar) is an ARB — an angiotensin receptor blocker — used to treat high blood pressure and to protect the kidneys in people with type 2 diabetes. It works by blocking a hormone called angiotensin II that constricts blood vessels, causing them to relax and lower blood pressure. Unlike ACE inhibitors (another common class of blood pressure medication), ARBs like losartan rarely cause the chronic dry cough that makes ACE inhibitors hard to tolerate for some people. It's taken once or twice daily and is generally very well-tolerated.
What it is
Losartan is an angiotensin II receptor blocker (ARB) that selectively blocks the AT1 receptor subtype of angiotensin II — the primary mediator of angiotensin II's vasoconstrictive, aldosterone-stimulating, and sodium-retaining effects. By blocking these effects, losartan causes blood vessel relaxation, reduces aldosterone secretion (leading to sodium and water excretion), and lowers blood pressure. Losartan is converted in the liver to an active metabolite (E-3174) that is 10–40 times more potent than the parent compound and has a longer duration of action.1
FDA-approved indications
Hypertension — treatment in adults and children 6 years and older.
Diabetic nephropathy — reduction of the rate of progression of renal disease in patients with type 2 diabetes mellitus and a history of hypertension and elevated serum creatinine and proteinuria.
Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy.1
Typical dosing
For hypertension: Starting dose 50 mg once daily; may be increased to 100 mg once daily. Patients with possible intravascular volume depletion (diuretic use) may start at 25 mg.1
Route of administration
Oral tablets.
Storage & handling
Store at controlled room temperature, protected from light.1
Common considerations
Boxed warning: Losartan can cause fetal harm and death when administered to pregnant women. Discontinue as soon as pregnancy is detected.1
Key considerations:
- Potassium levels: ARBs reduce aldosterone, which can raise serum potassium. Avoid potassium supplements, potassium-containing salt substitutes, and potassium-sparing diuretics without monitoring. Hyperkalemia is a real risk.
- Renal function: Can cause acute kidney injury, particularly in patients who are volume-depleted, have bilateral renal artery stenosis, or who are taking NSAIDs concurrently. Monitor creatinine periodically.
- NSAIDs: Concurrent use of NSAIDs (ibuprofen, naproxen) can reduce the antihypertensive effect of losartan and increase the risk of renal impairment.
- Lithium: ARBs can increase lithium levels; monitor lithium levels if both are used.
- First-dose hypotension: Patients who are volume-depleted or on diuretics may experience excessive blood pressure lowering with the first dose. Start at 25 mg in these patients.
- Cough: Unlike ACE inhibitors, ARBs like losartan do not cause chronic cough — this is a primary reason patients are switched from ACE inhibitors to ARBs.
- Angioedema: Rare, but has been reported with ARBs; more common in patients who had angioedema with ACE inhibitors previously.
References
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