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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.
• 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.
CNS: dizziness, insomnia, headache, asthenia, fatigue
EENT: sinus disorders
GI: nausea, vomiting, diarrhea, dyspepsia, abdominal pain
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
☞ 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.
• 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.