From the Guidelines
Losartan does not typically cause cough as a common side effect, making it a suitable alternative for patients who experience cough with ACE inhibitors. The mechanism of action of losartan, an angiotensin II receptor blocker (ARB), bypasses the pathway that leads to increased bradykinin levels, which are associated with the cough reflex seen in ACE inhibitors 1. This difference in mechanism is crucial, as ACE inhibitors are known to cause a dry, persistent cough in about 5-35% of patients due to their effect on bradykinin metabolism. In contrast, ARBs like losartan have been shown to have a lower incidence of cough compared to ACE inhibitors, with cough occurring in less than 1% of patients according to clinical data 1. Key points to consider include:
- The incidence of cough with losartan is similar to that of control drugs, making it a good option for patients who need renin-angiotensin system blockade but cannot tolerate ACE inhibitors due to cough 1.
- Losartan and other ARBs do not cause cough, including in patients with a history of ACE inhibitor-induced cough, as supported by accumulating evidence 1.
- The diagnosis of ACE inhibitor-induced cough is confirmed by the resolution of cough after cessation of the offending agent, usually within 1 to 4 weeks, but may be delayed in some patients up to 3 months 1. Overall, losartan is a viable option for patients who require renin-angiotensin system blockade but are intolerant of ACE inhibitors due to cough, given its low incidence of cough as a side effect 1.
From the FDA Drug Label
Cough Persistent dry cough (with an incidence of a few percent) has been associated with ACE-inhibitor use and in practice can be a cause of discontinuation of ACE-inhibitor therapy Cases of cough, including positive re-challenges, have been reported with the use of losartan in postmarketing experience.
Losartan and Cough: Losartan may cause cough, as reported in postmarketing experience, although the incidence is not as high as with ACE-inhibitors.
- The studies demonstrate that the incidence of cough associated with losartan therapy is similar to that associated with hydrochlorothiazide or placebo therapy.
- However, cases of cough have been reported with the use of losartan, including positive re-challenges. 2
From the Research
Losartan and Cough
- Losartan, an angiotensin II receptor antagonist, is not typically associated with cough as a side effect, unlike angiotensin-converting enzyme inhibitors (ACEIs) 3, 4, 5.
- A study comparing losartan to ACEIs found that the incidence of cough was significantly lower with losartan, suggesting that carry-over effects from previous ACEI use may contribute to reports of cough with losartan 3.
- However, there have been reports of losartan-induced cough, including a case study where a patient developed cough after starting losartan and had it resolve after switching to an ACEI, enalapril 6.
- Another study found that the incidence of cough with losartan was lower than with lisinopril, an ACEI, and similar to that with hydrochlorothiazide, a diuretic 5.
Comparison to ACEIs
- ACEIs are known to cause cough in some patients, which is thought to be related to the inhibition of kininase II and the accumulation of bradykinin and other peptides 6, 5.
- Losartan, as an angiotensin II receptor antagonist, does not inhibit kininase II and is therefore less likely to cause cough 5.
- However, patients who have previously experienced ACEI-induced cough may still report cough with losartan, possibly due to carry-over effects or other factors 3, 5.
Clinical Implications
- Losartan may be a suitable alternative for patients who experience cough with ACEIs 3, 4, 5.
- However, patients should be monitored for cough and other side effects when starting losartan, especially if they have a history of ACEI-induced cough 6, 5.
- Further studies are needed to fully understand the relationship between losartan and cough, as well as the long-term tolerability and efficacy of losartan in various patient populations 4, 7.