What is a suitable alternative dose of an angiotensin receptor blocker (ARB) to replace 20 mg of Lisinopril (angiotensin-converting enzyme inhibitor (ACEI)) for a patient experiencing a dry cough?

ARB Dose Equivalent for Lisinopril 20 mg

Switch to losartan 50 mg once daily or candesartan 8 mg once daily as the initial ARB dose when replacing lisinopril 20 mg for ACE inhibitor-induced cough. 1, 2

Recommended ARB Options and Starting Doses

The following ARBs are guideline-recommended alternatives with proven cardiovascular benefits equivalent to ACE inhibitors:

First-Line Options:

• Losartan 50 mg once daily is the most extensively studied ARB for patients with ACE inhibitor-induced cough, with demonstrated cough rates similar to placebo (17-29%) compared to lisinopril (62-69%) 3, 4
• Candesartan 8 mg once daily is specifically recommended in ACC/AHA guidelines as an appropriate starting dose, with demonstrated cough incidence (35.5%) significantly lower than enalapril (68.2%) and comparable to placebo (26.9%) 5, 6

Alternative Options:

• Valsartan 40 mg twice daily (or 80 mg once daily) showed cough incidence of 19.5% versus lisinopril 68.9%, with no difference from hydrochlorothiazide 5, 7
• Telmisartan 40 mg once daily demonstrated cough incidence of 15.6% versus lisinopril 60%, comparable to placebo 9.7% 4

Dose Titration Strategy

Double the ARB dose every 2-4 weeks if blood pressure remains ≥140/90 mm Hg and the medication is well-tolerated, targeting evidence-based maximum doses. 1

Target Maximum Doses:

• Losartan: 100 mg once daily 5, 8
• Candesartan: 32 mg once daily 5
• Valsartan: 160 mg twice daily 5
• Telmisartan: 80 mg once daily 2

Implementation Protocol

Immediate Steps:

• Discontinue lisinopril immediately as this is the only uniformly effective treatment for ACE inhibitor-induced cough, with resolution expected within 1-4 weeks (though may take up to 3 months) 1, 9
• Start ARB without washout period as guidelines support immediate switching 1

Monitoring Requirements:

• Check baseline renal function and potassium before initiating ARB therapy 1
• Reassess blood pressure (including postural changes), renal function, and potassium within 1-2 weeks after ARB initiation 5, 10, 1
• Monitor blood chemistry at 4-month intervals thereafter 1

Acceptable Laboratory Changes:

• Creatinine increases up to 50% above baseline or 266 μmol/L (3 mg/dL), whichever is smaller 1
• Potassium levels up to 5.5 mmol/L are acceptable 1
• If potassium rises above 5.5 mmol/L, halve the ARB dose and recheck within 1-2 weeks 1

Critical Safety Considerations

Angioedema Risk:

• Although rare (<1%), angioedema can occur with ARBs in patients who previously experienced angioedema with ACE inhibitors 10, 1
• Use caution during initial ARB treatment in patients with prior ACE inhibitor-induced angioedema, as cross-reactivity has been reported 1, 2
• If angioedema occurs with an ARB, discontinue immediately and avoid all ARBs for the patient's lifetime 1

Blood Pressure Management:

• Asymptomatic hypotension does not require dose adjustment 1
• Symptomatic hypotension requires reconsideration of other vasodilators and reduction of diuretic dose if no signs of congestion 1
• Patients with systolic blood pressure <80 mm Hg, low serum sodium, diabetes mellitus, and impaired renal function merit particularly close surveillance 5, 10

Common Pitfalls to Avoid

• Do not assume all cough is ACE inhibitor-related - exclude pulmonary edema and other respiratory causes before attributing cough to lisinopril 1
• Do not combine ARBs with both ACE inhibitors and aldosterone antagonists as this increases risk of hyperkalemia and renal dysfunction (Class III: Harm recommendation) 10, 1
• Do not stop concomitant nephrotoxic drugs (NSAIDs) or potassium supplements without first assessing for signs of congestion 1
• Avoid abrupt withdrawal of renin-angiotensin system inhibition as clinical deterioration is likely 1

Expected Cough Resolution Timeline

• Cough should resolve within 1-4 weeks after switching to an ARB, though may take up to 3 months in some patients 1, 2, 9
• ARBs have dramatically lower cough incidence (similar to placebo at 2-3%) compared to ACE inhibitors (7.9%) because they do not inhibit ACE and therefore don't cause bradykinin accumulation 2, 9

Alternative if ARB Not Tolerated

If ARBs are contraindicated or not tolerated, amlodipine 5 mg once daily has demonstrated ability to attenuate ACE inhibitor-induced cough in randomized controlled trials, with 61% of patients showing significant cough reduction 9