Losartan

An angiotensin II receptor blocker (ARB) used to treat hypertension and protect kidneys.

What is Losartan?

Losartan is an angiotensin II receptor blocker (ARB) that lowers blood pressure by blocking the effects of angiotensin II.

It helps relax blood vessels and reduces strain on the heart and kidneys.

History & Background

Losartan was the first ARB introduced into clinical practice and offered an alternative to ACE inhibitors without causing dry cough.

Chemical Structure & Properties

• IUPAC name: 2-butyl-4-chloro-1-[[2'-(1H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl]-1H-imidazole-5-methanol
• Molecular formula: C₂₂H₂₃ClN₆O
• Molar mass: 422.91 g/mol
• Functional groups: Tetrazole, imidazole, aromatic rings

Mechanism of Action

Losartan lowers blood pressure by:

• Blocking AT₁ receptors
• Preventing vasoconstriction
• Reducing aldosterone secretion

Pharmacokinetics

• Absorption: Well absorbed orally
• Peak plasma time: 1–2 hours
• Active metabolite: EXP-3174
• Half-life: 6–9 hours (metabolite longer)
• Excretion: Urine and bile

Medical Uses

• Hypertension
• Diabetic nephropathy
• Heart failure (alternative to ACE inhibitors)
• Stroke risk reduction

Dosage Guidelines

Adults: 25–100 mg once daily

Initial dose: 50 mg daily

⚠️ Monitor kidney function and potassium levels.

Side Effects

• Dizziness
• Hyperkalemia
• Fatigue
• Low blood pressure

Warnings & Precautions

• Avoid use in pregnancy
• Use caution in renal artery stenosis
• Monitor potassium levels

Drug Interactions

• Potassium supplements
• Potassium-sparing diuretics
• NSAIDs

Frequently Asked Questions

Does losartan cause cough? – No.

Is it kidney-protective? – Yes.

Is it safe in diabetes? – Yes.

Can it be taken long-term? – Yes.

⚠️ Educational content only. Not a substitute for professional medical advice.