| Starting Drug | Starting Dose | → | Target Drug | Equivalent Dose | |---------------|---------------|---|-------------|-----------------| | lisinopril | 40mg | → | losartan | 100mg | **Quick Answer:** Lisinopril 40mg is approximately equivalent to Losartan 100mg. ### Key Clinical Considerations * Losartan has a shorter half-life than lisinopril (2 hours vs. 12 hours), so a twice-daily dosing regimen for losartan (e.g. 50mg twice daily) may be considered to achieve more consistent 24-hour blood pressure control. * There is a relative contraindication to ARBs if a patient has a history of angioedema with ACE inhibitors, though the risk is lower with ARBs. ### Monitoring Requirements * Monitor blood pressure closely after conversion. * Monitor serum potassium and renal function within a few weeks of initiating the new medication. ### Important Notes * This conversion is based on typical dosing and equivalency ratios. Individual patient response may vary. * Ensure the patient is not pregnant or planning to become pregnant before initiating losartan, as both ACE inhibitors and ARBs are contraindicated in pregnancy. *Source: ACE Inhibitor to ARB Bidirectional Conversion Guide (Version 2.0, December 2024)* --- *Source: ACE Inhibitor to ARB Bidirectional Conversion Guide (Version 2.0, December 2024). This guide is based on clinical practice guidelines, pharmacokinetic studies, and cardiovascular outcome trials.*