Losartan

1. Introduction

Losartan is an angiotensin II receptor blocker (ARB) used to treat hypertension, protect kidney function in diabetic nephropathy, and reduce the risk of stroke in hypertensive patients. It works by blocking the effects of angiotensin II, leading to vasodilation and reduced blood pressure.

2. Indications

  • Approved Indications:
    • Hypertension.
    • Diabetic nephropathy in patients with type 2 diabetes and hypertension.
    • Stroke risk reduction in hypertensive patients with left ventricular hypertrophy.
  • Off-Label Uses:
    • Heart failure (as an alternative to ACE inhibitors).
    • Proteinuria reduction in non-diabetic kidney disease.

3. Dosage

  • Adults:
    • Hypertension: 50 mg once daily; may increase to 100 mg once daily.
    • Diabetic Nephropathy: 50 mg once daily; may increase to 100 mg once daily based on response.
    • Stroke Prevention: 50 mg once daily; may increase to 100 mg once daily based on blood pressure.
  • Children (≥6 years):
    • Initial dose: 0.7 mg/kg once daily (up to 50 mg/day).
  • Elderly:
    • Start at 25 mg once daily if there is a risk of hypotension or renal impairment.

4. Administration

  • Take orally, with or without food.
  • Take at the same time each day for consistent blood pressure control.

5. Forms Available

  • Tablets: 25 mg, 50 mg, 100 mg.

6. Side Effects

6.1. Common Side Effects

  • Dizziness.
  • Fatigue.
  • Hyperkalaemia.

6.2. Less Common Side Effects

  • Diarrhoea.
  • Muscle cramps.
  • Upper respiratory tract infections.

6.3. Rare but Serious Side Effects

  • Angioedema (swelling of the face, lips, tongue, or throat).
  • Hypotension.
  • Kidney dysfunction.

7. Warnings

  • Pregnancy: Contraindicated; may cause foetal harm or death if used during the second or third trimester.
  • Hyperkalaemia: Monitor potassium levels, especially in patients with renal impairment or taking potassium supplements.
  • Renal Impairment: Use cautiously in patients with severe kidney disease or bilateral renal artery stenosis.

8. Precautions

  • Monitor blood pressure regularly to ensure the desired therapeutic effect.
  • Avoid use in patients with severe hepatic impairment, as losartan is extensively metabolised by the liver.
  • Use cautiously in patients with a history of angioedema, although the risk is lower than with ACE inhibitors.

9. Interactions

  • Drug-Drug Interactions:
    • Potassium-sparing diuretics or supplements: Increased risk of hyperkalaemia.
    • NSAIDs: May reduce the antihypertensive effect and worsen kidney function.
    • Lithium: Increased risk of lithium toxicity.
  • Drug-Food Interactions:
    • Grapefruit juice: No significant interaction, but caution is advised.

10. Monitoring Parameters

  • Blood pressure (baseline and periodically).
  • Kidney function (e.g., serum creatinine, eGFR).
  • Potassium levels (especially in patients with renal impairment).

11. Use in Children

  • Approved for children ≥6 years old with hypertension. Dose adjustments are based on weight.

12. Use in Pregnancy

  • Category D: Contraindicated during pregnancy due to the risk of foetal toxicity, including renal dysfunction, skull hypoplasia, and death.

13. Use in Elderly

  • Safe for use at standard doses, but monitor for hypotension and kidney function due to potential age-related decline in renal function.

14. Use in Kidney Disease

  • Dose adjustments may be needed in severe renal impairment. Avoid in patients with bilateral renal artery stenosis or acute kidney injury.

15. Use in Liver Disease

  • Use cautiously in patients with hepatic impairment. Start with a lower dose (e.g., 25 mg daily).

16. Patient Counselling Points

  • Take losartan as prescribed, and do not skip doses.
  • Avoid potassium supplements or salt substitutes containing potassium unless directed by your doctor.
  • Inform your doctor immediately if you experience swelling of the face, lips, or throat.
  • Continue lifestyle modifications (e.g., healthy diet, exercise) alongside medication for optimal results.
  • Do not stop taking losartan suddenly without consulting your doctor, as it may worsen blood pressure control.

17. Table of Brand Names, Manufacturers, and Prices

Brand NameManufacturerPrice (USD)
CozaarMerck$30–50 (30 tablets, 50 mg)
Generic LosartanVarious manufacturers$5–20 (30 tablets, 50 mg)

18. FAQs (15 Questions)

  1. What is losartan used for?
    It is used to treat hypertension, protect kidneys in diabetic nephropathy, and reduce stroke risk in patients with high blood pressure.
  2. How does losartan work?
    It blocks angiotensin II receptors, relaxing blood vessels and lowering blood pressure.
  3. How long does it take for losartan to work?
    Blood pressure reduction may be seen within 1–2 weeks, with maximum effects in 4–6 weeks.
  4. Can losartan cause side effects?
    Yes, common side effects include dizziness, fatigue, and high potassium levels.
  5. Is losartan safe during pregnancy?
    No, it is contraindicated due to the risk of foetal harm.
  6. Can losartan cause kidney problems?
    It may worsen kidney function in patients with bilateral renal artery stenosis or severe kidney disease.
  7. Can I take losartan with other blood pressure medications?
    Yes, but monitor for excessive blood pressure lowering or increased potassium levels.
  8. Does losartan cause a dry cough?
    No, it does not typically cause a dry cough, unlike ACE inhibitors.
  9. Can losartan be stopped abruptly?
    No, stopping suddenly may worsen blood pressure. Consult your doctor before discontinuation.
  10. Does losartan interact with potassium supplements?
    Yes, it increases the risk of high potassium levels; avoid unless directed by your doctor.
  11. Is losartan safe for children?
    Yes, it is approved for children ≥6 years old with hypertension.
  12. Can losartan be used in heart failure?
    Yes, it is sometimes used off-label in patients intolerant to ACE inhibitors.
  13. How should losartan be stored?
    Store at room temperature, away from moisture and heat.
  14. Can losartan cause dizziness?
    Yes, dizziness is a common side effect, especially when starting treatment or at higher doses.
  15. Is losartan available as a generic medication?
    Yes, it is widely available in generic forms, making it more affordable.