Can a patient allergic to Angiotensin-Converting Enzyme (ACE) inhibitors take Angiotensin II Receptor Blockers (ARBs)?

ARBs for Patients Allergic to ACE Inhibitors

ARBs are recommended as the first-line alternative for patients who are allergic to ACE inhibitors, particularly those with ACE inhibitor-induced cough, though caution is advised in patients with a history of angioedema. 1

Safety of ARBs in ACE Inhibitor-Allergic Patients

• ARBs are the preferred alternative for patients who cannot tolerate ACE inhibitors due to cough, which occurs in 5-20% of patients taking ACE inhibitors 1, 2
• Unlike ACE inhibitors, ARBs do not inhibit kininase and are associated with a much lower incidence of cough and angioedema 1
• For ACE inhibitor-induced cough, ARBs have been shown to have a similar incidence of cough as placebo or hydrochlorothiazide in controlled trials 3

Cross-Reactivity Concerns with Angioedema

• While ARBs are alternatives for patients with ACE inhibitor-induced angioedema, caution is advised as some patients have also developed angioedema with ARBs 1
• The risk of cross-reactivity for angioedema between ACE inhibitors and ARBs is estimated to be approximately 10% or less 4
• Angioedema occurs in <1% of patients taking an ACE inhibitor but is more frequent in blacks and women 1
• If a patient has experienced life-threatening angioedema with an ACE inhibitor, clinical suspicion justifies avoidance of all ACE inhibitors for the lifetime of the patient 1

Prescribing ARBs After ACE Inhibitor Allergy

• ARBs should be started at low doses and titrated upward, with careful monitoring of blood pressure, renal function, and potassium levels within 1-2 weeks of initiation 1, 2
• Common ARBs with their initial and maximum doses include:
  • Candesartan: 4-8 mg once daily initially, maximum 32 mg once daily 1, 2
  • Losartan: 25-50 mg once daily initially, maximum 50-100 mg once daily 1, 2
  • Valsartan: 20-40 mg twice daily initially, maximum 160 mg twice daily 1, 2

Special Considerations

• ARBs should be given with caution to patients with low systemic blood pressure, renal insufficiency, or elevated serum potassium (>5.0 mEq/L) 1
• For patients with heart failure with reduced ejection fraction (HFrEF), ARBs are specifically recommended as an alternative to ACE inhibitors when patients are intolerant to ACE inhibitors 1
• Avoid routine combined use of an ARB with an ACE inhibitor as this combination increases risks without additional benefits 1, 5

Efficacy Comparison

• ARBs have been shown to be as effective as ACE inhibitors in reducing blood pressure and cardiovascular outcomes in patients with hypertension 6, 7
• In patients with heart failure, ARBs produce hemodynamic, neurohormonal, and clinical effects consistent with those expected after interference with the renin-angiotensin system 1, 8

Monitoring Recommendations

• After starting an ARB, reassess blood pressure, renal function, and potassium within 1-2 weeks 1, 9
• Pay particular attention to patients with diabetes, renal impairment, or low systolic blood pressure (<80 mm Hg) 1, 9