Is Losartan an ACE Inhibitor?

In this article, we will take a close look at Losartan and ACE inhibitors, two different classes of drugs used to manage hypertension and heart failure. We will explore their mechanisms of action, how they affect the renin-angiotensin system, and their respective side effects.
Klara Hatinova

Klara Hatinova

Klara is postgraduate researcher in experimental psychology at the
University of Oxford.

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What is Losartan?

Losartan, often marketed under the brand name Cozaar, is a medication that belongs to a class of drugs known as angiotensin II receptor antagonists. It is primarily used in the management of hypertension (high blood pressure) and heart failure [1].

How Does Losartan Work?

Losartan works by selectively blocking the binding of angiotensin II at the angiotensin II type 1 receptor. This unique mechanism of action sets it apart from other antihypertensive agents [2].

Angiotensin II is a hormone produced naturally in our body that can constrict blood vessels and stimulate the release of another hormone called aldosterone. Aldosterone increases the amount of sodium, and the body retains water. By blocking angiotensin II, losartan helps to relax and widen blood vessels, which lowers blood pressure [3].

In addition to its primary use, losartan can reduce protein excretion in urine, which occurs in proteinuria and specific aspects of kidney disease. Losartan could also increase the excretion of urea, the metabolic by-product found in urine [3].

What are ACE inhibitors?

Angiotensin-converting enzyme inhibitors, more commonly known as ACE inhibitors, are a class of medications mainly used to treat hypertension and heart failure. They block the formation of angiotensin II, a peptide that can constrict blood vessels and increase blood pressure. ACE inhibitors help relax the muscles in the blood vessels, causing their widening. This lowers blood pressure by reducing the force the blood needs to squeeze through the blood vessels. Reducing the force also reduces strain on the heart, as it doesn’t have to pump as hard [4, 5].

ACE inhibitors can also be prescribed for other conditions. For example, chronic renal insufficiency or atherosclerotic cardiovascular disease can be treated by ACE inhibitors. They can also reduce the risk of heart failure, heart attack, and general cardiovascular mortality [6, 7].

ACE Inhibitors: Side Effects

ACE inhibitors can have side effects, including a persistent dry cough and angioedema—swelling below the skin caused by water retention. In some cases, they can also cause renal insufficiency, occuring when not enough blood flows to supply the kidneys.

ACE inhibitors have been used for decades and are very well studied. Increased awareness of their side effects is motivating research into new classes of ACE inhibitors that would mitigate these side effects [8, 9, 10].

Is Losartan An ACE Inhibitor?

Losartan is not an ACE inhibitor. It is an angiotensin II receptor blocker that works by selectively blocking the interaction of angiotensin II with its receptor, which is different from blocking the formation of angiotensin II [11, 12, 13, 14].

Losartan and ACE Inhibitors: Similarities

Despite these differences, both ACE inhibitors and losartan are effective in treating conditions such as hypertension and heart failure. They both inhibit the renin-angiotensin system, which regulates blood pressure and fluid balance [11, 15].

Advantages: Losartan Over ACE Inhibitors

Losartan has some advantages over ACE inhibitors. For instance, it does not cause coughing, a common side effect of ACE inhibitors, because it does not impact ACE. Aside from processing Angiotensin II, the ACE enzyme also processes bradykinin and cough-inducing peptides [12]. You eliminate these side effects by blocking the binding of angiotensin II to its receptor.

On the other hand, a study found that ACE inhibitors are more suitable for patients with hyperglycaemia or type 2 diabetes [14].

Summary: Losartan Is Not An ACE Inhibitor

To answer your question, no, Losartan is not an ACE inhibitor. Losartan works by inhibiting the Angiotensin II type 1 receptor, whereas ACE inhibitors block the ACE enzyme that makes angiotensin II. The side effects of Losartan and ACE inhibitors are also different.

In all cases, consult your medical provider about which medication is best for you.

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Klara Hatinova

Klara Hatinova

Klara is a postgraduate researcher in experimental psychology at the University of Oxford. She has worked across a spectrum of hot topics in neuroscience, including her current project measuring reinforcement learning strategies in Parkinson’s disease. Previously, she studied the efficacy of psilocybin as a therapy for critical mental health conditions and examined molecular circadian rhythms of migraine disorders. She completed her undergraduate degree in Neuroscience at the University of Glasgow and participated in a year abroad at the University of California, where she worked on a clinical trial for spinal cord injury.