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losartan potassium


Pharmacologic class: Angiotensin II receptor antagonist

Therapeutic class: Antihypertensive

Pregnancy risk category C (first trimester), D (second and third trimesters)

FDA Box Warning

• When used during second or third trimester of pregnancy, drug may cause fetal harm or death. Discontinue as soon as pregnancy is detected.


Blocks vasoconstricting and aldosterone-secreting effects of angiotensin II at various receptor sites, including vascular smooth muscle and adrenal glands. Also increases urinary flow and enhances excretion of chloride, magnesium, calcium, and phosphate.


Tablets: 25 mg, 50 mg, 100 mg

Indications and dosages


Adults: Initially, 50 mg/day P.O.; range is 25 to 100 mg/day as a single dose or in two divided doses. May be used alone or with other drugs.

Children ages 6 and older: 0.7 mg/kg P.O. daily, up to total of 50 mg

To prevent cerebrovascular accident (stroke) in hypertensive patients with left ventricular hypertrophy (LVH)

Adults: Initially, 50 mg P.O. daily, increased to 100 mg P.O. daily. May be given concurrently with hydrochlorothiazide.

Nephropathy in patients with type 2 diabetes

Adults: 50 mg/day P.O.; increase to 100 mg/day based on blood pressure response.

Dosage adjustment

• Hepatic impairment

• Concurrent diuretic therapy


• Hypersensitivity to drug or its components

• Pregnancy (second and third trimesters)


Use cautiously in:

• heart failure, renal or hepatic impairment, obstructive biliary disorders

• high-dose diuretic therapy

• black patients

• pregnant patients (first trimester) or breastfeeding patients

• children younger than age 6 (safety not established).


• Administer with or without food.

• Know that if drug efficacy (measured at trough) is inadequate with once-daily dosing, prescriber may switch to twice-daily regimen using same or higher daily dosage.

• Be aware that drug may take 3 to 6 weeks to reach maximal efficacy.

Adverse reactions

CNS: dizziness, insomnia, headache, asthenia, fatigue

CV: hypotension

EENT: sinus disorders

GI: nausea, vomiting, diarrhea, dyspepsia, abdominal pain

Metabolic: hyperkalemia

Musculoskeletal: joint pain, back pain, muscle cramps

Respiratory: symptoms of upper respiratory infection, dry cough

Other: hypersensitivity reactions including angioedema


Drug-drug. Diuretics, other antihypertensives: increased risk of hypotension

Fluconazole: inhibited losartan metabolism, increased antihypertensive effects

Indomethacin: decreased losartan effects

Lithium: decreased lithium metabolism

Nonsteroidal anti-inflammatory drugs: decreased renal function

Potassium-sparing diuretics, potassium supplements: hyperkalemia

Rifamycins: enhanced losartan metabolism, decreased antihypertensive effects

Drug-diagnostic tests. Albumin: increased level

Drug-food. Salt substitutes containing potassium: hyperkalemia

Patient monitoring

Watch for angioedema and other hypersensitivity reactions.

• Monitor blood pressure to evaluate drug efficacy.

• Assess liver and kidney function tests and electrolyte levels.

• Stay alert for oliguria, progressive azotemia, and renal failure in patients with severe heart failure whose renal function depends on the renin-angiotensin-aldosterone system.

• Know that in black patients, losartan and other ACE inhibitors may be ineffective when used alone. Drug isn't indicated for stroke prevention in black hypertensive patients with LVH.

• Be aware that drug may cause fetal injury or death when used during second or third trimester of pregnancy.

Patient teaching

• Instruct patient to avoid potassium supplements and salt substitutes containing potassium, unless directed by prescriber.

Caution female patient not to take drug during second or third trimester of pregnancy. Advise her to contact prescriber immediately if she suspects pregnancy.

• Tell female patient to discuss breastfeeding with prescriber before taking.

Instruct patient to immediately report hypersensitivity reactions, especially lip or eyelid swelling, throat tightness, and difficulty breathing.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and foods mentioned above.

McGraw-Hill Nurse's Drug Handbook, 7th Ed. Copyright © 2013 by The McGraw-Hill Companies, Inc. All rights reserved


(loe-sar-tan) ,


(trade name)


Therapeutic: antihypertensives
Pharmacologic: angiotensin ii receptor antagonists
Pregnancy Category: D


Alone or with other agents in the management of hypertension.Treatment of diabetic nephropathy in patients with type 2 diabetes.Prevention of stroke in patients with hypertension and left ventricular hypertrophy.


Blocks the vasoconstrictor and aldosterone-secreting effects of angiotensin II at various receptor sites, including vascular smooth muscle and the adrenal glands.

Therapeutic effects

Lowering of BP in hypertensive patients.
Decreased progression of diabetic nephropathy.
Decreased incidence of stroke in patients with hypertension and left ventricular hypertrophy (effect may be less in black patients).


Absorption: Well absorbed but undergoes extensive first-pass hepatic metabolism, resulting in 33% bioavailability.
Distribution: Crosses the placenta.
Protein Binding: 99%.
Metabolism and Excretion: Undergoes extensive first-pass hepatic metabolism; 14% is converted to an active metabolite. 4% excreted unchanged in urine; 6% excreted in urine as active metabolite; some biliary elimination also occurs.
Half-life: 2 hr (6–9 hr for metabolite).

Time/action profile (antihypertensive effect†)

PO6 hr3–6 wks24 hr
†Onset of antihypertensive effect with chronic dosing


Contraindicated in: Hypersensitivity; Bilateral renal artery stenosis; Obstetric: Can cause injury or death of fetus – if pregnancy occurs, discontinue immediately. Lactation: Discontinue drug or use formula.
Use Cautiously in: Volume- or salt-depleted patients or patients receiving high doses of diuretics (correct deficits before initiating therapy or initiate at lower doses); genetic implication Black patients (reduction in stroke risk may not apply to this patient population); Impaired renal function due to primary renal disease or heart failure (may worsen renal function); Hepatic impairment (lower initial doses recommended); Women of childbearing potential; Pediatric: Children <6 yr (safety not established).

Adverse Reactions/Side Effects

Central nervous system

  • dizziness
  • fatigue
  • headache
  • insomnia
  • weakness


  • chest pain
  • edema
  • hypotension

Ear, Eye, Nose, Throat

  • nasal congestion


  • hypoglycemia
  • weight gain


  • diarrhea (most frequent)
  • abdominal pain
  • dyspepsia
  • nausea


  • impaired renal function

Fluid and Electrolyte

  • hyperkalemia


  • back pain
  • myalgia


  • angioedema (life-threatening)
  • fever


Drug-Drug interaction

Additive hypotension with other antihypertensives.Excessive hypotension may occur with concurrent use of diuretics.↑ risk of hyperkalemia with concurrent use of potassium supplements, potassium-containing salt substitutes, or potassium-sparing diuretics.↑ risk of hyperkalemia, renal dysfunction, hypotension, and syncope with concurrent use of ACE inhibitorsRifampin may ↓ antihypertensive effects.NSAIDs and selective COX-2 inhibitors may blunt the antihypertensive effect and ↑ the risk of renal dysfunction.May increase the effects ofamiodarone, fluoxetine, glimepiride, glipizide, phenytoin, rosiglitazone, sertraline and warfarin.


Oral (Adults) Hypertension–50 mg once daily initially (range 25–100 mg/day as a single daily dose or 2 divided doses) (initiate therapy at 25 mg once daily in patients who are receiving diuretics or are volume depleted). Prevention of stroke in patients with hypertension and left ventricular hypertrophy—50 mg once daily initially; hydrochlorothiazide 12.5 mg once daily should be added and/or dose of losartan ↑ to 100 mg once daily followed by an increase in hydrochlorothiazide to 25 mg once daily based on BP response; Nephropathy in patients with type 2 diabetes–50 mg once daily, may ↑ to 100 mg once daily depending on BP response.

Hepatic Impairment

Oral (Adults) Hypertension–25 mg once daily initially; may be ↑ as tolerated.
Oral (Children ≥ 6 yr) Hypertension–0.7 mg/kg once daily (up to 50 mg/day), may be titrated up to 1.4 mg/kg/day (or 100 mg/day).

Renal Impairment

(Children ≥6 yr) CCr < 30 mL/min—Contraindicated.

Availability (generic available)

Tablets: 25 mg, 50 mg, 100 mg
In combination with: hydrochlorothiazide (HyzaarRx); see combination drugs).

Nursing implications

Nursing assessment

  • Assess BP (lying, sitting, standing) and pulse frequently during initial dose adjustment and periodically during therapy. Notify health care professional of significant changes.
  • Monitor frequency of prescription refills to determine compliance.
  • Assess patient for signs of angioedema (dyspnea, facial swelling). May rarely cause angioedema.
  • Lab Test Considerations: Monitor renal function. May cause ↑ BUN and serum creatinine.
    • May cause ↑ AST, ALT, and serum bilirubin.
    • May cause hyperkalemia.
    • May cause slight ↓ hemoglobin and hematocrit.

Potential Nursing Diagnoses

Risk for injury (Adverse Reactions)
Noncompliance (Patient/Family Teaching)


  • Do not confuse Cozaar with Colace or Zocor.
    • Correct volume depletion, if possible, before initiation of therapy.
  • Oral: For patients with difficulty swallowing tablets, pharmacist can compound an oral suspension; stable for 4 wk if refrigerated. Shake suspension before each use.

Patient/Family Teaching

  • Emphasize the importance of continuing to take as directed, even if feeling well. Take missed doses as soon as remembered if not almost time for next dose; do not double doses. Medication controls but does not cure hypertension. Instruct patient to take medication at the same time each day. Warn patient not to discontinue therapy unless directed by health care professional.
  • Caution patient to avoid salt substitutes containing potassium or foods containing high levels of potassium or sodium unless directed by health care professional. See.
  • Caution patient to avoid sudden changes in position to decrease orthostatic hypotension. Use of alcohol, standing for long periods, exercising, and hot weather may increase orthostatic hypotension.
  • May cause dizziness. Caution patient to avoid driving or other activities requiring alertness until response to medication is known.
  • Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications.
  • Instruct patient to notify health care professional of medication regimen before treatment or surgery.
  • Instruct patient to notify health care professional if swelling of face, eyes, lips, or tongue or if difficulty swallowing or breathing occur.
  • Advise women of childbearing age to use contraception and notify health care professional if pregnancy is planned or suspected, or if breastfeeding. Losartan should be discontinued as soon as possible when pregnancy is detected.
  • Emphasize the importance of follow-up exams to evaluate effectiveness of medication.
  • Hypertension: Encourage patient to comply with additional interventions for hypertension (weight reduction, low-sodium diet, discontinuation of smoking, moderation of alcohol consumption, regular exercise, stress management). Medication controls but does not cure hypertension.
    • Instruct patient and family on proper technique for monitoring BP. Advise them to check BP at least weekly and to report significant changes.

Evaluation/Desired Outcomes

  • Decrease in BP without appearance of excessive side effects.
  • Delayed progression of diabetic nephropathy in patients with type 2 diabetes.
  • Decreased incidence of stroke in patients with hypertension and left ventricular hypertrophy.
Drug Guide, © 2015 Farlex and Partners


A trademark for the drug losartan potassium.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005
References in periodicals archive ?
The study received partial funding from Merck, which markets losartan (Cozaar).
Some commonly prescribed drugs in this class are candesartan (Atacand), eprosartan (Teveten), irbesarten (Avapro), losartan (Cozaar), telmisartan (Micardis) and valsartan (Diovan).
Leading global generic pharmaceutical manufacturers have been proactive in forging strategic alliances with branded pharmaceutical companies for marketing rights and exclusivity in producing generic versions of blockbuster drugs such as LIPITOR, Cozaar and Crestor, among others.
Washington, Jan 4 (ANI): Scientists have found that a commonly prescribed blood pressure medicine, losartan (Cozaar), prevents almost all of the lung damage caused from two months of exposure to cigarette smoke in mice.
ARBs include valsartan (Diovan), losartan (Cozaar), and irbesartan (Avapro).
There are seven single-ingredient ARBs approved by the FDA for treating hypertension: candesartan (Atacand), irbesartan (Avapro), olmesartan (Benicar), losartan (Cozaar), valsartan (Diovan), telmisartan (Micardis), and eprosartan (Teveten).
Drugs affected by the revisions include: Cozaar, Crixivan, Hyzaar, Isentress, Janumet, Januvia, Mevacor, Noroxin, Prinivil, Prinizide, Propecia, Proscar, Singulair, Zocor, and Zolinza.
The medication is currently sold under brand names as Diovan, Micardis, Cozaar, Benicar and Avapro.
Merck is developing new drugs to replace revenue as it faces generic competition that began last year to blood-pressure pills, Cozaar and Hyzaar, with combined 2009 sales of $3.6 billion.
Pharmaceutical company Mylan Inc (Nasdaq:MYL) revealed on Friday that its subsidiary Mylan Pharmaceuticals Inc received final approvals from the US Food and Drug Administration (FDA) for its Abbreviated New Drug Applications (ANDAs) for generic Hyzaar Tablets, 50 mg/12.5 mg and 100 mg/25 mg and Cozaar Tablets, 25 mg, 50 mg and 100 mg, both of which are antihypertensives.
For this reason the patient was treated for hypertension with Cozaar 100 mg daily for about a year.