From the Guidelines
No, a washout period is not necessary when switching from an Angiotensin-Converting Enzyme (ACE) inhibitor to an Angiotensin Receptor Blocker (ARB), but caution is advised due to the potential risk of angioedema. When transitioning, start the ARB at its recommended starting dose while discontinuing the ACE inhibitor. Both medication classes work on the renin-angiotensin-aldosterone system but through different mechanisms - ACE inhibitors block the conversion of angiotensin I to angiotensin II, while ARBs block angiotensin II receptors. This difference allows for a seamless transition without risking rebound hypertension or loss of blood pressure control, as noted in the 2017 ACC/AHA/HFSA focused update of the 2013 ACCF/AHA guideline for the management of heart failure 1. However, it is crucial to be aware of the potential for angioedema, particularly in patients with a history of this condition, as ACE inhibitors and ARBs can both be associated with this risk, although the mechanism and incidence may differ 1. Key considerations when switching include:
- Monitoring blood pressure after the switch to ensure adequate control
- Adjusting the ARB dose as needed at follow-up appointments
- Being vigilant for signs of angioedema, especially in high-risk patients such as blacks and those with a previous history of angioedema
- Understanding that while ARBs may be considered as alternative therapy for patients who have developed angioedema while taking an ACE inhibitor, caution is advised due to the possibility, albeit rare, of angioedema occurring with ARBs as well 1.
From the Research
Switching from ACE Inhibitors to Angiotensin Receptor Blockers
- The necessity of a washout period when switching from an Angiotensin-Converting Enzyme (ACE) inhibitor to an Angiotensin Receptor Blocker (ARB) is not directly addressed in the provided studies as a universal requirement.
- A study 2 found that switching from an ACEI to losartan is safe and effective without mentioning the need for a washout period.
- Another study 3 investigated the adherence to a 36-hour washout period when transitioning from ACEi to ARNI (angiotensin receptor/neprilysin inhibitor) and found no significant differences in outcomes between those who received the full washout and those who did not, but this study specifically deals with ARNI, not ARB.
Considerations for Specific Patient Groups
- For patients with heart failure with reduced ejection fraction (HFrEF), the guidelines recommend a washout period when switching from ACEi to ARNI, but the provided studies do not directly address the necessity of a washout for switching to ARB 3.
- In critically ill patients, early administration of ACEI/ARB is associated with reduced risk of in-hospital mortality, but the studies do not discuss washout periods for switching between these classes 4.
- The response to angiotensin II treatment in vasodilatory shock differs based on prior exposure to ACEi and ARB, suggesting that the effect of switching between these medications could vary depending on the clinical context, but does not directly address the need for a washout period 5.
General Use of ACE Inhibitors and Angiotensin Receptor Blockers
- The effectiveness of ACEi and ARB in patients with early (stage 1 to 3) non-diabetic chronic kidney disease is uncertain due to the low quality of evidence, and the question of a washout period when switching between them is not addressed in this context 6.