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Losartan (K)


Losartan (K) belongs to a new classs of nonpeptide angiotensin II receptor antagonist. Losartan (K) is potent and specific competitive antagonist of angiotensin AT1 receptors. itthe first orally active angiotensin II receptor antagonist. The blood pressure lowering efficacy of losartan is similar to that of of the angiotensin converting enzyme inhibitors (ACE) eg. Enalapril, but treatment with losartan is associated with a lower incidence of adverse effects.


Primary Characterstics

Molecular Structure of Losartan (K)
Losartan is the derivative of Losartan (K). It is of Synthetic origin and belongs to Imidazole. It belongs to Antihypertensive Agents pharmacological group.The Molecular Weight of Losartan (K) is 461.00.
Its pKa is 4.1.


Oral absorption of Losartan (K) is found to be 27.5% . Volume of distribution is found to be 34 litre and plasma protien binding is 99%. Presystemic metabolism is noted to be 33% and metabolism is reported Hepatic (extensively). Renal Excretion accounts for 35%, also excreted in bile and plasma half life is 1.5-2.5 hr.



Losartan (K) is contraindicated in conditions like Hyperaldoesteronism,Renal artery stenosis,Hypersensitivity,Pregnancy.

Drug Interactions

Losartan (K) is known to interact with other drugs, the details of drug interactions is as follows:

AldesleukinEnhanced hypotensive effect when aldesleukin given with Angiotensin-II receptor antagonists (e.g losartan)
AlprostadilEnhanced hypotensive effects when alprostadil given with Losartan (Angiotensin-II receptor antagonist).
DiazoxideEnhanced hypotensive effect when Diazoxide given with Losartan.
FluconazoleFluconazole increases the plasma concentration of losartan but decreases its active metabolite by inhibiting CYP450 2C9, an isoenzyme that convert losartan to its metabolite.ModerateClosely monitor for blood pressure whenever start, discontinue or change the dose of fluconazole. Itroconazole, ketoconazole and terbinafine are considered more safer alternatives of fluconazole and eprosartan is considered more safer alternative of losartan.
IndomethacinIndomethacin alters the antihypertensive effects of losartan by inhibiting synthesis of renal prostaglandins results in unopposed pressor activity producing hypertension.ModerateClosely monitor the patient for changed antihypertensive response whenever therapy with indomethacin starts, stopped or modified.
LithiumLosartan increases the plasma level of lithium by inhibiting secretion of aldosterone result in increased toxicity.ModerateClosely monitor the patient for lithium toxicity.

These interactions are sometimes beneficial and sometimes may pose threats to life. Always consult your physician for the change of dose regimen or an alternative drug of choice that may strictly be required.

Interference in Pathology

  • Rise in the Plasma Renin Activity
  • Increased Serum Potassium Level

Side Effects

The severe or irreversible adverse effects of Losartan (K), which give rise to further complications include Hypotension, Hypotension, Rhabdomyolysis.

The signs and symptoms that are produced after the acute overdosage of Losartan (K) include Bradycardia, Hypotension, Tachycardia.

The symptomatic adverse reactions produced by Losartan (K) are more or less tolerable and if they become severe, they can be treated symptomatically, these include Dizziness, Headache, Fatigue, Nausea, Diarrhea, Myalgia, Abdominal pain, Urticaria, Dyspepsia, Hypotension, Dry cough, Backache, Angioedema, Muscle pain, dizziness, dyspepsia, Rash.

Available Brands

Click on the appropriate strength of the dosage form to view its available brands.

Single Ingredient

Tabs: 25 mg, 50 mg, 100 mg,
Caplet: 50 mg,

Multi ingredient

Tabs: 50 mg, 100 mg,


Losartan (K)'s dosage details are as follows:
Dose Single Dose Frequency Route Instructions

Adult Dosage

50 to 100 mg75 (75)24 hourlyPOInitial dose may be reduced to 25 mg in salt depleted patients and patients with moderate to severe renal impairment.

Paedriatic Dosage ( 20 Kg. )

Not recommended for this age group

Neonatal Dosage ( 3 Kg. )

Not recommended in this age group

High Risk Groups

Drug should not be given to Paediatrics, Pregnant Mothers, patients suffering from Kidney dysfunction, patients suffering from Liver Malfunction, and Neonates.

If prescribing authority justifies the benefits of the drug against the possible damages he/she should reevaluate them and consult the reference material and previous studies.

Warning / Precautions

Losartan K should be used with caution in patients with any pre-existing kidney or liver disease, congestive heart failure (CHF), diabetes or any allergy, especially drug allergy. Get up slowly, to avoid dizziness and lightheadedness when rising from a seated or lying position. Also limit intake of alcoholic beverages because it may aggravate these effects. It should be used with caution while performing tasks requiring alertness because it may causes dizziness. Caution is advised when this drug is used in the elderly. This can cause harm to a fetus, so it is not recommended for use during pregnancy or lactation.

Storage Conditions


Store Below 40°C. Protect from Sunlight and Heat.

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