Switching from Lisinopril to Losartan
Yes, patients taking lisinopril can be safely switched to losartan, and this transition is well-supported by clinical evidence showing equivalent blood pressure control and similar safety profiles. 1, 2
Direct Switch Protocol
Switch immediately without a washout period—a randomized controlled trial demonstrated that starting losartan 50 mg once daily immediately after discontinuing an ACE inhibitor (captopril) was safe and effective, with no clinically significant initial hypotension requiring intervention. 2
Begin losartan at 50 mg once daily when switching from any dose of lisinopril, then titrate to 100 mg daily after 2–4 weeks if blood pressure remains ≥140/90 mmHg. 3
Monitor blood pressure every 2–4 weeks during the titration period, aiming to achieve a target of <130/80 mmHg within three months. 3
Evidence Supporting the Switch
The CORD IA trial enrolled 4,016 hypertensive patients who discontinued their ACE inhibitor and switched directly to losartan 50 mg once daily; blood pressure decreased significantly from 147.4/87.7 mmHg at baseline to 133.7/79.1 mmHg at one year (p<0.001), with no increase in adverse events and no changes in plasma sodium, potassium, urea, or creatinine. 1
A head-to-head comparison (CORD IB) showed no significant differences in blood pressure reduction between ramipril and losartan after one year, with both drugs achieving similar BP control (134.1/81.5 mmHg vs 134.5/80.2 mmHg). 1
Dry cough occurred 8 times less frequently with losartan compared to ACE inhibitors—this is the most common reason for switching and is well-documented in controlled rechallenge studies showing cough incidence of 17–29% with losartan versus 62–69% with lisinopril. 4, 1
Critical Safety Monitoring
Check serum creatinine and potassium within 1–2 weeks after switching, particularly in patients with diabetes, chronic kidney disease, or baseline renal impairment. 3, 5
Expect a small, transient rise in creatinine (0.1–0.3 mg/dL) related to hemodynamic changes rather than true tubular injury—this does not require discontinuation unless accompanied by evidence of acute tubular necrosis on urinalysis. 6
Monitor for hyperkalemia, especially in patients on potassium-sparing diuretics, aldosterone antagonists, or with eGFR <45 mL/min/1.73 m². 3
Renal Dysfunction Considerations
Losartan carries the same risk of renal dysfunction as ACE inhibitors in angiotensin-dependent states (bilateral renal artery stenosis, severe heart failure, volume depletion)—a review of case reports and the ELITE trial showed a 10.5% incidence of renal dysfunction with both losartan and captopril in elderly heart failure patients. 7
Do not assume losartan will be better tolerated from a renal standpoint if the patient developed renal dysfunction on an ACE inhibitor—published case reports include patients who developed renal dysfunction with both drug classes sequentially. 7
Losartan may be used in patients with underlying renal dysfunction if clinically indicated, but renal function must be monitored closely and the drug stopped if deterioration occurs. 7
Common Pitfalls to Avoid
Never combine losartan with an ACE inhibitor—dual renin-angiotensin system blockade increases the risk of hyperkalemia, syncope, and acute kidney injury by 2–3-fold without added cardiovascular benefit. 3, 5
Do not underdose—less than 25% of patients in clinical practice are titrated to the target dose of 100 mg daily for hypertension or 100–150 mg daily for heart failure, yet higher doses provide significantly better outcomes. 3
Avoid premature discontinuation for mild creatinine elevation—distinguish hemodynamic changes (which are expected and protective) from true acute tubular necrosis using urine microscopy and novel biomarkers if available. 6
Angioedema Risk
Angioedema can occur with losartan even in patients who previously tolerated ACE inhibitors, though it is rare—postmarketing reports document swelling of the larynx, glottis, face, lips, pharynx, and tongue. 4
History of ACE inhibitor-induced angioedema is a relative contraindication to losartan because cross-reactivity has been reported; if losartan is used in this setting, counsel the patient on warning signs and monitor closely. 5
Pregnancy Contraindication
- Losartan is absolutely contraindicated throughout pregnancy due to serious fetal toxicity (renal dysfunction, oligohydramnios, skull hypoplasia, fetal death)—discontinue immediately upon pregnancy detection and switch to methyldopa, labetalol, or extended-release nifedipine. 3