From the Guidelines
Losartan is a safer alternative to ACE inhibitors for patients with a history of angioedema, but it should be used with caution and monitoring due to the risk of cross-reactivity, as stated in the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1.
Key Considerations
- The risk of angioedema with losartan is approximately 0.1-0.2%, which is lower than the 0.3-1% risk with ACE inhibitors.
- Patients with a history of ACE inhibitor-induced angioedema may be cautiously switched to losartan after a washout period, but should be monitored closely due to the risk of cross-reactivity.
- Alternative antihypertensive medications like calcium channel blockers or thiazide diuretics should be considered for patients who have experienced angioedema with any renin-angiotensin system blocker.
Management of Angioedema
- If a patient develops angioedema while taking losartan, the medication should be discontinued immediately and not restarted.
- Angioedema from losartan typically presents as swelling of the face, lips, tongue, or throat and requires urgent medical attention as it can lead to airway compromise.
Mechanism and Cross-Reactivity
- The mechanism of losartan-induced angioedema differs from ACE inhibitor-induced angioedema, as it is related to its effects on the angiotensin II receptor rather than bradykinin accumulation.
- There is about a 10% cross-reactivity between ACE inhibitors and losartan, which should be taken into account when switching medications.
From the FDA Drug Label
The following additional adverse reactions have been reported in postmarketing experience with losartan. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to estimate their frequency reliably or to establish a causal relationship to drug exposure: Hypersensitivity: Angioedema, including swelling of the larynx and glottis, causing airway obstruction and/or swelling of the face, lips, pharynx, and/or tongue has been reported rarely in patients treated with losartan; some of these patients previously experienced angioedema with other drugs including ACE inhibitors.
Angioedema has been reported rarely in patients treated with Losartan. Some of these patients had previously experienced angioedema with other drugs, including ACE inhibitors 2.
From the Research
Losartan and Angioedema
- Losartan, an angiotensin II receptor antagonist, has been associated with angioedema in some cases 3, 4, 5, 6.
- A case report described a 62-year-old woman who experienced angioedema after taking losartan, which resolved after discontinuation of the drug and administration of antihistamines 3.
- Another study found that 32% of patients who experienced angioedema due to angiotensin-converting enzyme (ACE) inhibitors also experienced angioedema with angiotensin II receptor blockers, including losartan 4.
- The mechanism of losartan-induced angioedema is not fully understood, but it may not be due to bradykinin excess 3.
- Clinicians should be aware that angiotensin receptor antagonists, including losartan, may not be safe alternatives for patients with a history of angioedema secondary to ACE inhibitors 3, 4.
Risk Factors and Precautions
- Patients with a prior history of angioedema due to ACE inhibitors may be at increased risk of experiencing angioedema with losartan 4.
- Losartan should be used with caution in patients with renal impairment or liver dysfunction 5, 6.
- The drug should not be administered to pregnant women or breast-feeding mothers, as it may disturb fetal growth or be harmful to the newborn 6.
- Losartan may cause hyperkalemia when used with potassium-sparing diuretics, such as spironolactone or triamterene 6.