Neprilysin inhibitors are medicines that block an enzyme called neprilysin, which normally breaks down helpful signaling peptides in your body. By slowing that breakdown, these drugs can raise the levels of peptides that support blood vessel relaxation, sodium excretion, and lower cardiac stress, which is why they matter most in cardiovascular medicine.
Why neprilysin matters
Neprilysin is a zinc-dependent membrane enzyme found in tissues such as the kidneys, blood vessels, and central nervous system. It helps degrade several bioactive peptides, including natriuretic peptides, bradykinin, adrenomedullin, and others that influence blood pressure, fluid balance, and vascular tone.
In simple terms, neprilysin acts like a cleanup enzyme. When you inhibit it, more of those beneficial peptides stay active for longer, which can improve hemodynamic and neurohormonal balance in the right clinical setting.
How they work
Neprilysin inhibitors prevent the enzyme from breaking down peptides that help the heart and blood vessels work more efficiently. The best-known effect is amplification of the natriuretic peptide system, which promotes vasodilation, natriuresis, and diuresis while reducing pressure and volume overload.
They also affect other substrates, which is why the effects are broader than just blood pressure reduction. Neprilysin also acts on bradykinin, substance P, endothelin, angiotensin I, and angiotensin II, so inhibition can produce both helpful and unwanted effects depending on the patient and the drug combination used.
Main drug types
In practice, you most often hear about neprilysin inhibition as part of an angiotensin receptor-neprilysin inhibitor or ARNI. The most established example is sacubitril/valsartan, where sacubitril inhibits neprilysin and valsartan blocks the angiotensin II receptor.
There have also been single-target neprilysin inhibitors and older dual-pathway drugs studied over time. However, the modern clinical success of this class has come mainly from combining neprilysin inhibition with renin-angiotensin system blockade, which helps offset the rise in angiotensin-related vasoconstriction that neprilysin inhibition alone can permit.
Where they are used
The clearest and most important use is in heart failure, especially heart failure with reduced ejection fraction. Reviews and clinical evidence describe neprilysin inhibition as a major advance because it improves outcomes beyond symptom control when used appropriately as part of ARNI therapy.
They have also been studied in hypertension and other cardiovascular settings. Evidence suggests sacubitril/valsartan can lower blood pressure effectively, and some reviews note possible additional effects on renal and metabolic parameters, though heart failure remains the core indication where the class is best established.
Benefits you should know
Neprilysin inhibition can help the body do several useful things at once. It can reduce blood vessel constriction, increase sodium and water excretion, lower filling pressures, and improve the hormonal environment that drives heart failure progression.
Because the mechanism targets multiple peptides rather than a single pathway, the class may produce effects that look broader than a standard blood pressure drug. That broader effect is part of why ARNI therapy has become so important in modern cardiovascular treatment.
Risks and limitations
The same biology that creates benefits also creates risks. Reported adverse effects include hypotension and renal impairment, and neprilysin inhibition can increase bradykinin-related peptide activity, which raises concern for tolerability in some patients.
Another key issue is that neprilysin also helps break down substances that are not purely beneficial, so indiscriminate inhibition is not always desirable. That is one reason modern treatment favors combination strategies and careful patient selection rather than neprilysin inhibition as a stand-alone concept for every condition.pubmed.
Who should be careful
People with low blood pressure, kidney dysfunction, or complex heart failure regimens need especially careful assessment before starting therapy in this class. Clinical reviews emphasize that the balance of substrate effects can vary with disease stage, so very advanced heart failure may respond less predictably.
You should also treat the class as a prescription cardiovascular therapy, not a general wellness drug. It works best when a clinician matches it to the right diagnosis, the right dose, and the right background treatment.
Neprilysin and Alzheimer’s research
Neprilysin has also attracted interest outside cardiology because it participates in the breakdown of amyloid-related peptides in the brain. That has led to research interest in Alzheimer’s disease, but this area remains more investigational and less established clinically than its heart failure role.
That distinction matters. The strongest real-world evidence and routine use are cardiovascular, while neurological applications are still largely research-driven and should not be presented as established standard therapy.
Difference from ACE inhibitors
People sometimes confuse neprilysin inhibitors with ACE inhibitors because both influence vasoactive peptides and both can affect bradykinin. The difference is that ACE inhibitors block angiotensin-converting enzyme, while neprilysin inhibitors block peptide breakdown through a different pathway.
That is why ARNI therapy combines neprilysin inhibition with angiotensin receptor blockade rather than replacing the whole renin-angiotensin system approach. This combination helps deliver the benefits of peptide preservation while controlling the unwanted rise in angiotensin-mediated effects.
Practical takeaway
You can think of neprilysin inhibitors as drugs that preserve helpful hormones your body already makes. Their main value comes from improving cardiovascular physiology, especially in heart failure, where they help reduce strain on the heart and improve outcomes when used correctly.