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- What is losartan, and how does it work (mechanism of action)?
- What brand names are available for losartan?
- Is losartan available as a generic drug?
- Do I need a prescription for losartan?
- What are the side effects of losartan?
- What is the dosage for losartan?
- Which drugs or supplements interact with losartan?
- Is losartan safe to take if I'm pregnant or breastfeeding?
- What else should I know about losartan?
What is losartan, and how does it work (mechanism of action)?
Losartan is an oral medication that belongs to a class of drugs called angiotensin receptor blockers (ARBs). Other ARBs include irbesartan (Avapro), valsartan (Diovan), and candesartan (Atacand). Angiotensin formed in the blood by the action of angiotensin converting enzyme (ACE) is a powerful chemical that attaches to angiotensin receptors found in many tissues but primarily on smooth muscle cells of blood vessels. Angiotensin's attachment to the receptors causes the muscle cells to contract and the blood vessels to narrow (vasoconstrict) which leads to an increase in blood pressure (hypertension). Losartan (more specifically, the chemical formed when the liver converts the inactive losartan into its active form) blocks the angiotensin receptor. By blocking the action of angiotensin, losartan relaxes muscle cells and dilates blood vessels thereby reducing blood pressure.
Losartan was approved by the FDA in April 1995.
What are the side effects of losartan?
Side effects reported included:
Losartan also may cause:
Losartan may reduce kidney function in some patients and should not be used by patients who have bilateral renal artery stenosis (narrowing of both arteries going to the kidneys).
Rare cases of rhabdomyolysis (muscle breakdown) have been reported.
Quick GuideHow to Lower Blood Pressure: Exercise Tips
What is the dosage for losartan?
The starting dose of losartan for adults is 25-50 mg daily. The maximum dose is 100 mg daily. The total daily dose may be divided and administered two doses daily. Losartan may be given with or without food.
The starting dose of losartan for pediatric patients 6 years of age or older is 0.7 mg/kg up to 50 mg once daily. Doses more than 1.4 mg/kg or 100 mg daily have not been evaluated in pediatric patients.
Which drugs or supplements interact with losartan?
Losartan may increase levels of blood potassium (hyperkalemia), which can lead to serious heart problems (arrhythmias). Therefore, concomitant use of other drugs or substances that increase blood-such as potassium-sparing diuretics (for example, spironolactone [Aldactone], triamterene, and amiloride), potassium supplements, or salt substitutes containing potassium may lead to dangerous increases in serum potassium.
Combining losartan or other ARBs with nonsteroidal anti-inflammatory drugs (NSAIDs) in patients who are elderly, fluid-depleted (including those on diuretic therapy), or with poor kidney function may result in reduced kidney function, including kidney failure. These effects usually are reversible.
- ibuprofen (Advil, Children's Advil/Motrin, Medipren, Motrin, Nuprin, PediaCare Fever, etc.),
- indomethacin (Indocin, Indocin-SR), and
- naproxen (Anaprox, Naprelan, Naprosyn, Aleve).
Combining ARBs, ACE inhibitors, or aliskiren (Tekturna) increases risk of hypotension (low blood pressure), hyperkalemia, and reduces kidney function compared to each drug used alone and there is no additional benefit on preventing end stage kidney disease or death.
Aliskiren and losartan should not be combined in patients with diabetes or with renal impairment.
Is losartan safe to take if I'm pregnant or breastfeeding?
When used in the second or third trimester of pregnancy , ARBs can cause injury and even death to the fetus. Losartan should not be used during pregnancy. When pregnancy is first detected, losartan should be stopped.
It is not known whether losartan is excreted in breast milk, but losartan and its active form are excreted in rat milk. Due to the possibility of harm to the nursing infant, if possible, losartan should be discontinued by females who are nursing.
What else should I know about losartan?
What preparations of losartan are available?
Tablets: 25, 50 and 100 mg
How should I keep losartan stored?
Tablets should be stored at room temperature in a tightly closed, light resistant container.
Reference: FDA Prescribing Information
Quick GuideHow to Lower Blood Pressure: Exercise Tips
Losartan (Cozaar) is a medication prescribed fro the treatment of high blood pressure. Losartan (Cozaar) belongs to a class of drugs referred to as ARBs (angiotensin receptor blockers). Side effects, drug interactions, warnings and precautions, and pregnancy and breastfeeding safety information should be reviewed prior to taking any medication.
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