Can an angiotensin receptor blocker (ARB) be given to an asthmatic patient?

Using ARBs in Asthmatic Patients

Angiotensin receptor blockers (ARBs) are safe and recommended for asthmatic patients, especially when ACE inhibitors cannot be tolerated due to cough or angioedema. 1

Safety Profile of ARBs in Asthma

• Unlike ACE inhibitors, ARBs do not inhibit kininase and are associated with a much lower incidence of cough and angioedema, making them suitable for asthmatic patients 1
• ARBs do not affect bronchial tone or airway hyperresponsiveness, unlike beta-blockers which are contraindicated in asthma 2, 3
• Clinical trials demonstrate that the incidence of cough with ARBs is similar to that of placebo or hydrochlorothiazide, even in patients who previously experienced ACE inhibitor-induced cough 4

Advantages of ARBs over ACE Inhibitors in Asthmatic Patients

• ACE inhibitors can increase bronchial hyperreactivity and may worsen or even induce asthma by opposing inactivation of tachykinins and bradykinins 5, 3
• Recent research shows that people with active asthma are more likely to switch from ACE inhibitors to ARBs, suggesting better tolerability of ARBs 6
• ARBs produce hemodynamic, neurohormonal, and clinical effects consistent with renin-angiotensin system blockade without the respiratory side effects of ACE inhibitors 1

Prescribing ARBs for Asthmatic Patients

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

Precautions and Monitoring

• Use caution in patients with low systemic blood pressure, renal insufficiency, or elevated serum potassium (>5.0 mEq/L) 1
• While ARBs are alternatives for patients with ACE inhibitor-induced angioedema, caution is advised as some patients have also developed angioedema with ARBs 1
• Monitor for potential side effects including dizziness, hypotension, hyperkalemia, and renal dysfunction 4

Special Considerations

• ARBs may be particularly beneficial in asthmatic patients with heart failure, as they are recommended for patients with HFrEF who are ACE inhibitor intolerant 1
• The number needed to treat to prevent switching from ACE inhibitors varies by age, sex, and BMI, ranging between 4 and 21, and is lowest in older women with a BMI of 25 or greater 6
• Avoid routine combined use of an ARB with an ACE inhibitor and aldosterone antagonist, as this combination increases risks of hypotension, renal dysfunction, and hyperkalemia 1

In conclusion, ARBs represent a safe and effective option for asthmatic patients requiring renin-angiotensin system blockade, with a significantly lower risk of respiratory adverse effects compared to ACE inhibitors.