Losartan
Angiotensin II Receptor Blocker (ARB)
Generic Name
Losartan
Drug Class
Angiotensin II receptor antagonist (ARB)
Indications
- Hypertension
- Heart failure
- Diabetic nephropathy (type 2 diabetes with proteinuria)
- Left ventricular hypertrophy (risk reduction for stroke in hypertensive patients)
Dosage
- Hypertension (adults): 50 mg orally once daily; may increase to 100 mg/day if needed
- Heart failure: 25–50 mg orally once daily; titrate as tolerated
- Diabetic nephropathy: 50 mg orally once daily; may increase to 100 mg/day
- Children (6–16 yrs): 0.7 mg/kg orally once daily (max 50 mg/day)
Note: Adjust dose in hepatic or renal impairment; monitor renal function and electrolytes.
Route of Administration
Oral (tablet)
Mechanism of Action
Losartan selectively blocks angiotensin II type 1 (AT1) receptors, preventing vasoconstriction, aldosterone release, and sympathetic activation. This reduces blood pressure, decreases cardiac workload, and protects renal function.
Common Adverse Effects
- Dizziness
- Fatigue
- Hypotension
- Headache
- Hyperkalemia (mild)
Serious Adverse Effects
- Severe hypotension
- Angioedema (rare, life-threatening)
- Renal dysfunction
- Hyperkalemia (severe)
Contraindications
- Pregnancy (especially 2nd and 3rd trimester)
- History of angioedema related to ARBs
- Severe bilateral renal artery stenosis
- Hypersensitivity to losartan
Precautions
- Monitor blood pressure, renal function, and electrolytes regularly
- Use caution in elderly patients and those with renal or hepatic impairment
- Avoid potassium supplements unless indicated
Drug Interactions
- Other antihypertensives – additive hypotensive effect
- Potassium-sparing diuretics or supplements – risk of hyperkalemia
- NSAIDs – may reduce antihypertensive effect and impair renal function
Pregnancy & Lactation
Contraindicated in pregnancy (2nd/3rd trimester). Use caution during breastfeeding; consult healthcare provider.
Patient Counseling
- Take at the same time each day
- Monitor blood pressure and report dizziness
- Do not stop therapy abruptly
- Report swelling, rash, or signs of hyperkalemia