Dose Recommendations and Equivalence for Irbesartan and Losartan

Hypertension Dosing Guidelines

• The 2018 American College of Cardiology/American Heart Association hypertension guideline recommends a starting dose of losartan 50 mg once daily, with a usual therapeutic range of 50–100 mg daily for most patients with hypertension. 1

Heart‑Failure Dosing Evidence

• In patients with heart failure with reduced ejection fraction, the HEAAL randomized trial demonstrated that losartan 150 mg daily provides superior clinical outcomes compared with 50 mg daily, preventing one additional cardiovascular event per 31 patients treated over four years (high‑quality evidence, Class I, Level A). 3

Dose‑Equivalence Guidance

• Current clinical guidelines do not define an established dose‑equivalence ratio between irbesartan and losartan; therefore, direct substitution based on “starting doses” is not supported. 3 (The same conclusion is echoed in the 2018 hypertension guideline.) 1 (Additional confirmation appears in the 2018 guideline update.) 2