Losartan Starting Dose
The standard starting dose of losartan for adults is 50 mg once daily, which can be increased to a maximum of 100 mg once daily as needed for blood pressure control. 1
Standard Adult Dosing
For most adults with hypertension, initiate losartan at 50 mg once daily 1. This dose provides near-maximum antihypertensive effects in controlled trials 2. If blood pressure remains uncontrolled after several weeks, the dose can be titrated up to 100 mg once daily 1.
Special Populations Requiring Dose Adjustment
Volume-Depleted Patients or Those on Diuretics
Start with 25 mg once daily in patients with possible intravascular volume depletion, particularly those already taking diuretics 1. This lower starting dose minimizes the risk of symptomatic hypotension, though losartan carries a lower risk of first-dose hypotension compared to ACE inhibitors 3.
Hepatic Impairment
In patients with mild-to-moderate hepatic impairment, reduce the starting dose to 25 mg once daily 1. Plasma concentrations of losartan are approximately 5 times higher in hepatically impaired patients compared to healthy volunteers 1. Losartan has not been studied in severe hepatic impairment and should be avoided in this population 1.
Elderly Patients
No dose adjustment is necessary for elderly patients 1. The 2007 ESH/ESC guidelines emphasize that while initial doses and titration should be more gradual in very old and frail subjects due to greater risk of adverse effects, standard dosing can be used in most elderly patients 4. Clinical trials showed comparable efficacy and safety in patients over 65 years 1, 3.
Renal Impairment
No dose adjustment is required for renal impairment, including patients on hemodialysis 1, 5. Pharmacokinetic studies demonstrate that steady-state drug levels remain stable across all degrees of renal insufficiency 6. However, if the patient has both renal impairment AND volume depletion, start with 25 mg daily 1.
Important Caveats Regarding Potassium-Sparing Diuretics
When losartan is combined with potassium-sparing diuretics (including aldosterone antagonists like spironolactone), close monitoring of serum potassium is essential 7. While the FDA label does not mandate a specific dose reduction, clinical judgment suggests:
- Check potassium and renal function within 3 days and at 1 week after initiation 8
- Monitor at least monthly for the first 3 months 8
- Consider discontinuing or reducing potassium supplements 8
- Be particularly cautious in patients with estimated creatinine clearance <50 mL/min 8
Recent evidence suggests that high dietary potassium intake may diminish the antiproteinuric effects of losartan, though blood pressure control remains intact 9.
Target Dosing for Heart Failure
For heart failure with reduced ejection fraction (HFrEF), the target dose is 100 mg once daily (with some guidelines recommending up to 150 mg daily, though FDA approval only extends to 100 mg) 10. The HEAAL trial demonstrated that 150 mg daily was superior to 50 mg daily for reducing death or heart failure hospitalization 11, though current FDA labeling limits the maximum dose to 100 mg 10.
Titrate to target doses over 2-week intervals rather than remaining on subtherapeutic doses, as higher doses provide greater clinical benefit 12, 10.
Pediatric Considerations
For children aged 6-16 years with hypertension, start at 0.7 mg/kg once daily (maximum 50 mg), with a maximum dose of 1.4 mg/kg or 100 mg daily 1. Losartan is not recommended in children under 6 years or with estimated GFR <30 mL/min/1.73 m² 1.