What is the incidence of dry cough with losartan (angiotensin II receptor antagonist) compared to ACE (angiotensin-converting enzyme) inhibitors?

Incidence of Dry Cough with Losartan vs. ACE Inhibitors

Losartan and other angiotensin II receptor blockers (ARBs) have a significantly lower incidence of dry cough (17-29%) compared to ACE inhibitors (62-69%), making ARBs the preferred alternative for patients who experience ACE inhibitor-induced cough. 1

Comparative Incidence Rates

• ACE inhibitors cause dry cough in approximately:

  • 5-35% of patients overall 2
  • 5-10% of Caucasian patients
  • Up to 50% of Chinese patients 1

• Losartan and other ARBs cause cough in approximately:

  • 17-29% of patients 1
  • Similar to placebo or hydrochlorothiazide in controlled studies 3

Clinical Evidence

In controlled clinical trials specifically designed to assess cough:

• In patients with a history of ACE inhibitor-induced cough:

  • Lisinopril (ACE inhibitor) caused cough in 62-69% of patients
  • Losartan caused cough in only 17-29% of patients
  • Placebo/hydrochlorothiazide caused cough in 25-35% of patients 1, 4, 5

• FDA data confirms that losartan has a cough incidence similar to placebo or hydrochlorothiazide in patients with previous ACE inhibitor-induced cough 3

Mechanism of Action Differences

The significant difference in cough incidence is explained by the different mechanisms of action:

• ACE inhibitors block the conversion of angiotensin I to angiotensin II and inhibit the degradation of bradykinin and substance P, which accumulate and can trigger cough 2, 1

• ARBs like losartan selectively block the angiotensin II type 1 receptor without affecting bradykinin metabolism, thus avoiding the mechanism that causes cough 4

Clinical Implications

• For patients who develop cough on ACE inhibitors, switching to losartan or another ARB is recommended by the American College of Chest Physicians (Grade A recommendation) 1

• Initial losartan dosing should be 25-50 mg once daily, with a maximum dose of 50-100 mg once daily 1

• When switching from an ACE inhibitor to losartan due to cough:

  1. Discontinue the ACE inhibitor
  2. Allow 1-4 weeks for cough resolution (may take up to 3 months in some cases) 2
  3. Initiate losartan therapy

Caveats and Considerations

• Some patients switched to losartan may still experience cough (17-29%), but this is often due to:

  • Carry-over effects from previous ACE inhibitor use 6
  • Other underlying causes of cough
  • In studies, 91% of patients who discontinued losartan due to cough had previously been prescribed an ACE inhibitor 6

• ARBs like losartan can still cause other side effects similar to ACE inhibitors:

  • Hypotension
  • Worsening renal function
  • Hyperkalemia 1

• Monitor renal function and potassium levels within 1-2 weeks of starting losartan, especially when used with potassium-sparing diuretics 1

• While rare, angioedema can occur with ARBs, so use caution if the patient has a history of ACE inhibitor-induced angioedema 1