ACE Inhibitors vs ARBs: Lisinopril and Losartan
How do ACE inhibitors and ARBs differ?
ACE inhibitors and ARBs interrupt the renin-angiotensin system at different points. Lisinopril inhibits ACE, reducing conversion of angiotensin I to angiotensin II. Losartan blocks the angiotensin II AT1 receptor. Both can affect blood pressure, potassium and renal function, but ACE inhibition also reduces bradykinin breakdown.
Key takeaways
- ACE inhibition blocks an enzyme; an ARB blocks a receptor.
- Bradykinin helps explain why cough is associated with ACE inhibitors.
- Different mechanisms do not eliminate shared potassium and renal risks.
What changes with ACE inhibition?
ACE contributes to conversion of angiotensin I into angiotensin II. Reducing that conversion lowers angiotensin-mediated vasoconstrictor and aldosterone signaling. ACE also breaks down bradykinin, so inhibition changes more than angiotensin production.
That additional effect helps explain the association with cough. It is a mechanism comparison, not a reason to infer the cause of every cough in a person taking the medicine.
What changes with an ARB?
Losartan blocks AT1 receptors rather than inhibiting ACE. It interrupts an important angiotensin II signal without increasing bradykinin through ACE inhibition in the same way.
This does not mean an ARB has zero adverse-effect overlap. Angioedema has been reported with losartan. Avoid turning a lower association into an absolute claim that a reaction cannot occur.
Why monitor potassium and renal function with both?
Both classes alter the renin-angiotensin-aldosterone pathway. Susceptible patients can develop hyperkalemia or deterioration in renal function, so the patient’s context and serial results matter.
Those risks do not mean the drugs are universally kidney-damaging; they also have specific beneficial indications. This comparison does not recommend combining the classes, choosing a dose or changing a prescribed medicine.
