What happens when Losartan is administered orally?
Losartan is an angiotensin II receptor antagonist used to treat high blood pressure and protect the kidneys from damage due to diabetes. When administered orally, Losartan is well absorbed by the gastrointestinal tract, with peak plasma concentrations occurring within 1-2 hours after dosing [1]. It undergoes extensive first-pass metabolism, primarily by the liver enzyme CYP2C9, into its active metabolite E-3174 [2].
How does Losartan work in the body?
Losartan works by blocking the action of angiotensin II, a potent vasoconstrictor that constricts blood vessels and increases blood pressure. By blocking angiotensin II receptors, Losartan causes blood vessels to relax and dilate, reducing blood pressure and decreasing the workload on the heart [3]. This is particularly beneficial for people with hypertension, heart failure, and kidney disease.
What are the common dosing regimens for Losartan?
The recommended starting dose of Losartan is 50mg per day, which can be increased to 100mg daily if necessary [4]. The maximum dose is generally not to exceed 150mg daily. Losartan can be taken with or without food, but food may slightly affect its absorption and peak levels in the blood.
Who should not take Losartan?
Losartan is contraindicated in patients with known hypersensitivity to the drug or its components. Additionally, it's not recommended for children under 6 years old and patients with severe kidney impairment.
Interactions and warnings
Losartan may interact with other medications, such as blood thinners, and should be used cautiously in patients with kidney disease or those taking NSAIDs, which can increase the risk of kidney damage. Patients should inform their healthcare providers about any medications they're taking before starting Losartan.
References:
[1] https://www.drugpatentwatch.com/drug/losartan (DrugPatentWatch.com)
[2] Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th ed.
[3] Clinical Pharmacology, 14th ed.
[4] Losartan potassium, prescribing information (https://www.medscape.com/viewarticle/777142#vp_2)
Sources:
1. https://www.drugpatentwatch.com/drug/losartan (DrugPatentWatch.com)
2. Goodman & Gilman's The Pharmacological Basis of Therapeutics, 13th ed., by Laurence L. Brunton
3. Clinical Pharmacology, 14th ed., by Bertram G. Katzung
4. Losartan Potassium, prescribing information, accessed June 18, 2026.