No Washout Period Required When Switching from Losartan to Entresto
When transitioning a patient from losartan (an ARB) to Entresto (sacubitril/valsartan), you can start Entresto immediately without any washout period. The mandatory 36-hour washout only applies when switching from an ACE inhibitor, not from an ARB 1.
Key Distinction: ACE Inhibitors vs. ARBs
The FDA labeling for Entresto explicitly states: "ENTRESTO is contraindicated with concomitant use of an angiotensin-converting enzyme (ACE) inhibitor. If switching from an ACE inhibitor to ENTRESTO allow a washout period of 36 hours between administration of the two drugs" 1.
Notice that ARBs (like losartan) are not mentioned in this washout requirement. This is because:
- The angioedema risk that necessitates the washout period occurs when combining neprilysin inhibition with ACE inhibition (both block bradykinin degradation pathways)
- ARBs do not inhibit ACE and therefore do not carry the same angioedema risk when combined with neprilysin inhibition 2
- Entresto itself contains valsartan (an ARB), so you're essentially switching from one ARB to another ARB plus neprilysin inhibition
Practical Implementation
Simply stop the losartan and start Entresto the next day. The transition is straightforward:
- Stop losartan at the patient's last dose
- Begin Entresto at the appropriate starting dose (typically 49/51 mg twice daily for most patients, or 24/26 mg twice daily if the patient has concerns about tolerability) 1
- Monitor blood pressure, renal function, and potassium within 1-2 weeks
Common Pitfall to Avoid
Do not confuse this with ACE inhibitor transitions. The 36-hour washout is mandatory only for ACE inhibitors (enalapril, lisinopril, ramipril, etc.) due to the serious risk of angioedema when neprilysin and ACE inhibition overlap 3, 4. This risk does not apply to ARB-to-Entresto transitions.
Monitoring Considerations
While no washout is needed, you should still:
- Check baseline potassium and creatinine before starting Entresto
- Monitor for hypotension, especially in the first few weeks
- Assess renal function and electrolytes within 1-2 weeks of initiation
- Titrate to target dose (97/103 mg twice daily) after 2-4 weeks as tolerated 1