Brand name: Cozaar
Drug class: Angiotensin II Receptor Antagonists

Medically reviewed by Drugs.com on Jan 10, 2025. Written by ASHP.

Introduction

Angiotensin II receptor type 1 (AT₁) antagonist (i.e., angiotensin II receptor blocker, ARB).

Uses for Losartan Potassium

Hypertension

Management of hypertension (alone or in combination with other classes of antihypertensive agents, including diuretics). Monotherapy used to treat hypertension in adults and pediatric patients ≥6 years of age.

Angiotensin II receptor antagonists are recommended as one of several preferred agents for the initial management of hypertension according to current evidence-based hypertension guidelines. While there may be individual differences with respect to recommendations for initial drug selection and use in specific patient populations, current evidence indicates that these antihypertensive drug classes all generally produce comparable effects on overall mortality and cardiovascular, cerebrovascular, and renal outcomes.

Stroke Reduction in Left Ventricular Hypertrophy

Reduction of the risk of stroke in patients with hypertension and left ventricular hypertrophy.

Evidence suggests that the benefit associated with losartan-based antihypertensive therapy does not apply to Black patients.

Preliminary evidence suggests that aspirin therapy at baseline in patients receiving losartan may reduce the risk of combined cardiovascular death, stroke, and acute MI compared with aspirin therapy at baseline in patients receiving atenolol.

Diabetic Nephropathy

Management of diabetic nephropathy manifested by elevated S_cr and proteinuria (urinary albumin to creatinine ratio ≥300 mg/g) in patients with type 2 diabetes mellitus and hypertension.

Recommended option in patients with diabetes mellitus, hypertension, and moderately to severely elevated albuminuria (i.e., urine to creatinine ratio >30 mg/g). May also be considered in patients with diabetes and albuminuria who are normotensive^{† [off-label]} .

Angiotensin II receptor antagonists have been used in the management of nondiabetic CKD with moderately or severely increased albuminuria^{† [off-label]} to prevent progression of CKD.

Use may be considered in patients with CKD and normal to mildly increased albuminuria^{† [off-label]} (i.e., urinary albumin to creatinine ratio <30 mg/g) when other compelling indications (e.g., hypertension, heart failure, or low ejection fraction) present.

Heart Failure

Angiotensin II receptor antagonists have been used in the management of heart failure^{† [off-label]}.

Current guidelines on management of heart failure recommend ACE inhibitors for treatment of patients with presymptomatic heart failure (i.e., Stage B disease) who have a left ventricular ejection fraction (LVEF) ≤40%; angiotensin II receptor antagonists may be used in such patients with a recent MI who are intolerant to ACE inhibitors. Angiotensin receptor-neprilysin inhibitors (ARNIs) are recommended first-line for treatment of symptomatic heart failure with reduced ejection fraction (HFrEF); angiotensin II receptor antagonists are only recommended when an ARNI is contraindicated, inaccessible, or poorly tolerated. Angiotensin II receptor antagonists may be considered in patients with a LVEF between 41–49% to reduce the risk of hospitalizations for heart failure and cardiovascular mortality.

Mortality Reduction After Acute MI

Used to improve survival in hemodynamically stable patients with acute MI^{† [off-label]} .

Expert guidelines recommend initiation of an oral ACE inhibitor within the first 24 hours of acute MI in patients with an anterior infarct, heart failure, or ejection fraction ≤40% who do not have any contraindications (e.g., hypotension, shock, renal dysfunction). In patients who are intolerant to ACE inhibitors, an angiotensin II receptor antagonist is recommended, and has been shown to have similar benefits on survival.

Losartan Potassium Dosage and Administration

General

Pretreatment Screening

• Verify pregnancy status in females of reproductive potential.

• Evaluate and correct sodium or volume depletion.

Patient Monitoring

• Monitor blood pressure.

• Monitor renal function periodically.

• Monitor serum potassium periodically.

Dispensing and Administration Precautions

• The Institute for Safe Medication Practices (ISMP) includes Cozaar (losartan potassium), Colace (docusate sodium), and Zocor (simvastatin) on their ISMP List of Confused Drug Names, and recommends using special safeguards to ensure the accuracy of prescriptions for these drugs.

Other General Considerations

• May administer with other antihypertensive agents.

• Blood pressure control should be part of a comprehensive cardiovascular risk management plan, including (as appropriate) lipid control, diabetes management, antithrombotic therapy, smoking cessation, exercise, and limited sodium intake.

Administration

Oral Administration

Administer orally without regard to meals. Available as tablets. Also commercially available in fixed-combination tablets containing losartan potassium and hydrochlorothiazide; see the full prescribing information for administration of this combination product.

Preparation of an Oral Suspension from Losartan Tablets

Administer extemporaneously prepared oral suspension in patients unable to swallow tablets. Preparation of extemporaneous suspension containing losartan potassium 2.5 mg/mL: Add 10 mL of purified water to a 240-mL amber polyethylene terephthalate (PET) bottle containing ten 50-mg tablets of losartan potassium; shake contents for ≥2 minutes. Allow concentrated suspension to stand for 1 hour following reconstitution, then shake for an additional minute. Separately, prepare a mixture containing equal parts (by volume) of syrup (Ora-Sweet SF) and suspending vehicle (Ora-Plus). Dilute the concentrated suspension of losartan potassium with 190 mL of the Ora-Sweet SF and Ora-Plus mixture; shake the container an additional minute to disperse ingredients. Shake suspension before dispensing each dose.

Dosage

Available as losartan potassium; dosage expressed in terms of the salt.

Pediatric Patients

Hypertension

Oral

Children ≥6 years of age: Initially, 0.7 mg/kg (up to 50 mg) once daily. .Adjust dosage based on BP response.

Dosages >1.4 mg/kg (or >100 mg) daily not studied in pediatric patients.

Adults

Hypertension

Oral

Adults without intravascular volume depletion: 50 mg once daily initially. May increase to 100 mg once daily if needed for BP control.

Adults with possible depletion of intravascular volume (e.g., on diuretic therapy): 25 mg once daily initially.

Stroke Reduction in Left Ventricular Hypertrophy

Oral

50 mg once daily initially. Depending on BP response, add hydrochlorothiazide 12.5 mg daily and/or increase losartan dosage to 100 mg once daily.

Diabetic Nephropathy

Oral

50 mg once daily initially; may increase to 100 mg once daily based on BP response.

Heart Failure†

Oral

25–50 mg once daily initially; target dosage of 150 mg daily.

Special Populations

Hepatic Impairment

Mild to moderate hepatic impairment: initiate at 25 mg once daily.

Severe hepatic impairment: not studied.

Renal Impairment

No dosage adjustment necessary for adults with renal impairment unless volume depleted.

Not recommended for use in pediatric patients with eGFR <30 mL/minute per 1.73 m².

Geriatric Patients

No dosage recommendations at this time.

Cautions for Losartan Potassium

Contraindications

• Known hypersensitivity to losartan or any ingredient in the formulation.

• Concomitant therapy with aliskiren in patients with diabetes mellitus.

Warnings/Precautions

Warnings

Fetal/Neonatal Morbidity and Mortality

Risk of fetal harm when administered to a pregnant woman (See Boxed Warning). Possible reduction in fetal renal function and increase in fetal and neonatal morbidity and mortality when drugs that act on the renin-angiotensin system (RAS) are used during the second and third trimesters of pregnancy. Oligohydramnios caused by drugs that act on the RAS can result in fetal lung hypoplasia, skeletal deformations (including skull hypoplasia), anuria, hypotension, renal failure, and death. Discontinue losartan immediately when pregnancy detected. If there is no appropriate alternative therapy, apprise the mother of the potential risk to the fetus. If losartan is taken during pregnancy, perform serial ultrasound examinations to assess intra-amniotic environment; if oligohydramnios observed, discontinue losartan, unless it is considered life-saving for the mother. Oligohydramnios may not appear until after irreversible injury to the fetus. Closely observe neonates exposed to losartan in utero for signs of hypotension, oliguria, and hyperkalemia. If oliguria or hypotension occurs, support BP and renal perfusion. Exchange transfusions or dialysis may be required.

Other Warnings and Precautions

Hypotension in Volume- or Salt-Depleted Patients

Possible symptomatic hypotension, particularly in volume- and/or salt-depleted patients (e.g., those treated with diuretics). Correct volume or salt depletion prior to losartan administration.

Renal Function Deterioration

Changes in renal function, including acute renal failure, possible. Patients with renal artery stenosis, CKD, severe congestive heart failure, or volume depletion at higher risk of acute renal failure.

Monitor renal function periodically. Consider withholding or discontinuing losartan in patients who develop a clinically important reduction in renal function while receiving losartan.

Hyperkalemia

Hyperkalemia can develop with concomitant use of agents that increase serum potassium concentration (e.g., potassium-sparing diuretics, potassium supplements, potassium-containing salt substitutes).

Monitor serum potassium periodically and treat appropriately. Dosage reduction or discontinuation of therapy may be required.

Use of Fixed Combinations

When losartan is used in fixed combination with hydrochlorothiazide, the cautions, precautions, and contraindications associated with both drugs must be considered. Consult the full prescribing information for the fixed combination preparation for specific information.

Specific Populations

Pregnancy

May cause fetal harm when administered to a pregnant woman. Possible reduction in fetal renal function and increase in fetal and neonatal morbidity and mortality when drugs that act on the RAS are used during the second and third trimesters of pregnancy. Oligohydramnios caused by drugs that act on the RAS can result in fetal lung hypoplasia, skeletal deformations (including skull hypoplasia), anuria, hypotension, renal failure, and death.

Discontinue losartan immediately when pregnancy detected. If no appropriate alternative exists, apprise the mother of the potential risk to the fetus. If losartan is taken during pregnancy, perform serial ultrasound examinations to assess intra-amniotic environment; if oligohydramnios observed, discontinue losartan, unless it is considered life-saving for the mother. Oligohydramnios may not appear until after irreversible injury to the fetus. Closely observe neonates exposed to losartan in utero for signs of hypotension, oliguria, and hyperkalemia. If oliguria or hypotension occurs, support BP and renal perfusion. Exchange transfusions or dialysis may be required.

Lactation

Losartan and its active metabolite are distributed into milk in rats; not known whether distributed into human milk. Discontinue breastfeeding or the drug.

Pediatric Use

Antihypertensive effects of losartan established in hypertensive pediatric patients 6–16 years of age.

Safety and efficacy not established in children <6 years of age or in pediatric patients with glomerular filtration rate <30 mL/minute per 1.73 m².

Geriatric Use

No substantial differences in pharmacokinetics, safety, or efficacy of losartan monotherapy relative to younger adults, but increased sensitivity cannot be ruled out.

Hepatic Impairment

Systemic exposure to losartan and its active metabolite may be increased. Initial dosage adjustment recommended in mild to moderate hepatic impairment; losartan not studied in severe hepatic impairment.

Renal Impairment

Plasma concentrations and AUCs of losartan and its active metabolite increased and renal clearance reduced in patients with mild (Cl_cr 50–74 mL/minute) or moderate (Cl_cr 30–49 mL/minute) renal insufficiency. Not removed by hemodialysis. No dosage adjustments recommended in patients with renal impairment unless they are also volume depleted.

Black Patients

BP reduction may be smaller in Black patients. No evidence that the benefits of losartan in reducing the risk of cardiovascular events in hypertensive patients with left ventricular hypertrophy apply to Black patients.

Common Adverse Effects

Adverse effects (incidence ≥2%) include dizziness, upper respiratory infection, nasal congestion, back pain.

Drug Interactions

In vitro studies indicate CYP2C9 and 3A4 are involved in biotransformation of losartan to active and inactive metabolites.

Drugs Affecting Hepatic Microsomal Enzymes

Pharmacodynamic consequences of concomitant use of losartan and CYP2C9 inhibitors have not been studied.

Drugs Increasing Serum Potassium

Hyperkalemia may occur with concomitant administration of losartan and other drugs that raise serum potassium levels. Monitor serum potassium levels if used concomitantly.

Specific Drugs

Losartan Potassium Pharmacokinetics

Absorption

Bioavailability

Well absorbed after oral administration but undergoes substantial first-pass metabolism.

Systemic bioavailability of losartan is about 33%.

Peak plasma concentrations of losartan and its active metabolite attained at 1 and 3–4 hours, respectively, following oral administration.

Onset

Antihypertensive effect evident within 1 week, with maximum BP reduction after 3–6 weeks.

Food

Food slows absorption of losartan and decreases its peak plasma concentration but has minimal effect on AUC of losartan or its active metabolite.

Special Populations

In patients with hepatic impairment, oral bioavailability is about 2 times higher than in those with normal hepatic function.

In patients with mild to moderate alcoholic cirrhosis, plasma concentration of losartan and its active metabolite were about 5 and 1.7 times those of healthy individuals, respectively.

In patients with mild (Cl_cr 50–74 mL/minute) or moderate (Cl_cr 30–49 mL/minute) renal impairment, plasma concentrations and AUC of losartan and its active metabolite are increased by 50–90%.

Distribution

Extent

Crosses the blood-brain barrier poorly in animals.

Distributed into milk in rats; not known whether distributed into human milk.

Plasma Protein Binding

Losartan and its active metabolite highly protein bound (plasma free fractions: 1.3 and 0.2%, respectively).

Elimination

Metabolism

CYP2C9 and 3A4 involved in metabolism of losartan.

Elimination Route

Urine: 35% (4% unchanged, 6% active metabolite)

Feces (via bile): 60%

Half-life

Losartan terminal half-life: 2 hours.

Active metabolite: 6-9 hours.

Special Populations

In patients with mild to moderate alcoholic cirrhosis, total plasma clearance of losartan is about 50% lower than in those with normal hepatic function.

In patients with mild or moderate renal impairment, renal clearance of losartan and its active metabolite is decreased by 55–85%. Neither losartan nor its active metabolite is removed by hemodialysis.

Stability

Storage

Oral

Extemporaneous Suspension

2.5-mg/mL preparation of losartan potassium tablets in a mixture of syrup (Ora-Sweet SF) and suspending vehicle (Ora-Plus) : Up to 4 weeks at 2–8°C.

Tablets

25°C (excursions permitted between 15–30°C). Protect from light.

Actions

• Nonpeptide tetrazole derivative; reversible, non-competitive inhibitor of the angiotensin II receptor (type AT1).

• Losartan (prodrug) requires activation in the liver to exert pharmacologic activity

• Active carboxylic acid metabolite is 10-40 times more potent by weight than losartan and appears to be a reversible, noncompetitive inhibitor of the AT₁ receptor.

• Blocks the physiologic actions of angiotensin II, including vasoconstrictor and aldosterone-secreting effects.

• Does not inhibit ACE; does not bind to or block other hormone receptors or ion channels known to be important in cardiovascular regulation.

Advice to Patients

• Advise patients not to use potassium supplements or salt substitutes containing potassium without consulting their clinician.

• Advise females of reproductive potential on the risks of losartan use during pregnancy. Discuss treatment options with women planning to become pregnant.

• Advise patients to inform their clinician if they are or plan to become pregnant or plan to breast-feed.

• Advise patients to inform their clinician of existing or contemplated concomitant therapy, including prescription and OTC drugs and dietary and herbal supplements, as well as any concomitant illnesses.

• Advise patients of other important precautionary information.

Additional Information

The American Society of Health-System Pharmacists, Inc. represents that the information provided in the accompanying monograph was formulated with a reasonable standard of care, and in conformity with professional standards in the field. Readers are advised that decisions regarding use of drugs are complex medical decisions requiring the independent, informed decision of an appropriate health care professional, and that the information contained in the monograph is provided for informational purposes only. The manufacturer’s labeling should be consulted for more detailed information. The American Society of Health-System Pharmacists, Inc. does not endorse or recommend the use of any drug. The information contained in the monograph is not a substitute for medical care.

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name

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