Losartan Dose Equivalent to Olmesartan 40 mg
The equivalent losartan dose for olmesartan 40 mg is approximately 100 mg once daily, based on comparative efficacy trials showing olmesartan 40 mg achieves similar or superior blood pressure reductions to losartan 100 mg. 1, 2
Evidence from Direct Comparative Trials
Head-to-Head Efficacy Data
Olmesartan 40 mg demonstrated superior blood pressure reduction compared to losartan 100 mg in a forced-titration study of 941 patients, with olmesartan achieving 9.7 mm Hg diastolic reduction versus 7.1 mm Hg with losartan (treatment difference -2.5 mm Hg, P<0.0001) 2
The same trial showed olmesartan 40 mg reduced systolic blood pressure by 13.6 mm Hg compared to 9.7 mm Hg with losartan 100 mg (treatment difference -3.9 mm Hg, P=0.0001) 2
A significantly greater proportion of patients achieved blood pressure goal <140/90 mm Hg with olmesartan 40 mg compared to losartan 100 mg at 8 weeks of treatment 2
24-Hour Ambulatory Blood Pressure Monitoring
Olmesartan 20 mg (half the dose in question) was more effective than losartan 50 mg, valsartan 80 mg, and irbesartan 150 mg across all ambulatory blood pressure monitoring timepoints 3
Goal rates for 24-hour ambulatory blood pressure <130/80 mm Hg were significantly higher with olmesartan than losartan at comparable or lower doses 3
Guideline-Based Dosing Context
Standard Dosing Ranges
The ACC/AHA guidelines list olmesartan's usual dose range as 20-40 mg once daily and losartan's range as 50-100 mg once or twice daily 4
For heart failure with reduced ejection fraction, the target dose of losartan is 100 mg once daily, representing the maximum therapeutic dose 5
Clinical Implications
If switching from olmesartan 40 mg to losartan, start with losartan 100 mg once daily to maintain equivalent blood pressure control 5, 2
Monitor blood pressure within 2-4 weeks after switching, as individual response may vary despite population-level equivalence 4
Consider that olmesartan 40 mg may actually provide superior efficacy to losartan 100 mg, so some patients may require addition of a second agent (such as a thiazide diuretic) after switching 2, 6
Important Caveats
Both medications share the same contraindications: avoid in pregnancy, do not combine with ACE inhibitors, and monitor for hyperkalemia especially in patients with chronic kidney disease 4, 5
Losartan may be dosed once or twice daily (50 mg twice daily totaling 100 mg), which can provide more consistent 24-hour coverage in some patients 5
The superior efficacy of olmesartan over losartan has been demonstrated across multiple trials at various dose comparisons, suggesting olmesartan has greater intrinsic potency per milligram 1, 6