What is the recommended treatment and dosage of Losartan (angiotensin II receptor blocker) for an adult patient with a history of hypertension or diabetic nephropathy?

Losartan Treatment for Hypertension and Diabetic Nephropathy

For adult patients with hypertension and diabetic nephropathy, start losartan at 50 mg once daily and titrate to 100 mg once daily based on blood pressure response and tolerability. 1

Dosing by Indication

Diabetic Nephropathy (Type 2 Diabetes)

• Start at 50 mg once daily and increase to 100 mg once daily based on blood pressure response 1
• This dosing is supported by landmark evidence showing losartan 100 mg daily reduced end-stage renal disease by 28% (P=0.002) and doubled serum creatinine by 25% (P=0.006) in patients with type 2 diabetes and nephropathy 2
• The 100 mg dose is optimal for renoprotection, providing 48% reduction in albuminuria compared to 30% with 50 mg (P<0.01) 3
• Titrate to the highest approved dose tolerated (maximum 100 mg daily) to maximize renoprotective benefits 4

Hypertension Without Nephropathy

• Start at 50 mg once daily for most patients 1
• Use 25 mg once daily as starting dose if volume depleted (e.g., on diuretic therapy) 1
• Maximum dose is 100 mg once daily 1
• Doses of 50-100 mg once daily produce systolic/diastolic blood pressure reductions of 5.5-10.5/3.5-7.5 mmHg 1

Hypertension with Left Ventricular Hypertrophy

• Start at 50 mg once daily, add hydrochlorothiazide 12.5 mg daily, then increase losartan to 100 mg daily followed by hydrochlorothiazide to 25 mg daily based on blood pressure response 1
• This combination reduced cardiovascular mortality by 37% (P=0.03) and total mortality by 39% (P=0.002) in diabetic patients with left ventricular hypertrophy 5

Special Populations

Hepatic Impairment

• Start at 25 mg once daily in patients with mild-to-moderate hepatic impairment 1
• Losartan has not been studied in severe hepatic impairment 1

Pediatric Patients (6-16 years)

• Start at 0.7 mg/kg once daily (maximum 50 mg total) 1
• Maximum dose is 1.4 mg/kg daily (not to exceed 100 mg) 1
• Not recommended in children <6 years or with eGFR <30 mL/min/1.73 m² 1

Advanced CKD

• Start at lower doses in patients with eGFR <45 mL/min/1.73 m² 6
• A modest rise in serum creatinine (10-20%) after initiation is expected and hemodynamic, not indicative of kidney injury unless persistent 6

Critical Monitoring Requirements

Initial Monitoring

• Check serum creatinine and potassium within 2-4 weeks after initiation or dose increase 4, 6
• The European Heart Journal recommends monitoring within 1 week of starting treatment 6

Ongoing Monitoring Thresholds

• Halve the dose if creatinine rises to >220 μmol/L (2.5 mg/dL) 6
• Stop losartan immediately if creatinine rises to >310 μmol/L (3.5 mg/dL) 6
• Halve the dose if potassium rises to >5.5 mmol/L 6
• Stop losartan immediately if potassium rises to ≥6.0 mmol/L 6

Combination Therapy Considerations

When to Add Additional Agents

• Add hydrochlorothiazide 12.5 mg if blood pressure goals not achieved with losartan monotherapy 1
• Addition of hydrochlorothiazide 12.5 mg to losartan 50 mg produces blood pressure reductions of 15.5/9.2 mmHg 1
• Consider adding a calcium channel blocker if blood pressure targets remain unmet 7

Absolute Contraindications for Combination

• Never combine losartan with ACE inhibitors, other ARBs, or direct renin inhibitors 4, 6
• This combination increases adverse effects (hypotension, hyperkalemia, acute renal failure) without additional benefit 6
• Avoid combining losartan with potassium-sparing diuretics (e.g., spironolactone) due to compounded hyperkalemia risk 6

Common Pitfalls and Caveats

Temporary Medication Suspension

• Temporarily suspend losartan during interval illness, planned IV radiocontrast administration, bowel preparation for colonoscopy, or prior to major surgery 6
• This prevents acute kidney injury during periods of hemodynamic stress 6

Hyperkalemia Risk Factors

• Patients with moderate-to-severe CKD (eGFR <45 mL/min/1.73 m²) are at higher risk 6
• Losartan typically increases serum potassium by approximately 1 mEq/L 6
• Monitor potassium more frequently in patients with diabetes or CKD 6

Bilateral Renal Artery Stenosis

• Risk of acute renal failure in patients with severe bilateral renal artery stenosis 6
• Screen for this condition before initiating therapy in high-risk patients 6

Blood Pressure Targets

• Target blood pressure <130/80 mmHg for patients with diabetes or chronic kidney disease 8
• Regular blood pressure monitoring is essential to assess response to therapy 8