What Do ACE Inhibitors Do, and How Do They Work?
Key takeaways:
Angiotensin-converting enzyme (ACE) inhibitors are a group of medications that treat high blood pressure and heart failure. But ACE inhibitors do several other things. For example, they can lower the risk of death after a heart attack and protect the kidneys in kidney disease.
ACE inhibitors’ mechanism of action is to decrease levels of a hormone called angiotensin II. This relaxes your blood vessels, which lowers blood pressure. ACE inhibitors also help your kidneys remove more water and sodium.
ACE inhibitors can start lowering your blood pressure almost immediately after you take them. But taking your ACE inhibitor daily is key to getting its full benefits.
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Maybe your grandma took one, maybe your dad, and now you too. Yes, ACE inhibitors have been around that long. They’ve been saving lives for generations.
Over 40 years ago, the first ACE inhibitor was designed after a blood-pressure-lowering substance found in snake venom. Today there are 10 FDA-approved ACE inhibitors on the market. Lisinopril (Zestril, Qbrelis) is by far the most commonly prescribed one. Other examples include enalapril (Vasotec) and benazepril (Lotensin).
ACE inhibitors “block” an enzyme (protein) called ACE, which stands for angiotensin-converting enzyme. But how does this lower blood pressure, protect your heart, and prevent kidney problems? In this article, we’ll explain what ACE inhibitors do, how they work, and how their mechanism of action sets them apart from other blood pressure medications.
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What do ACE inhibitors do?
ACE inhibitors are best known for lowering blood pressure. In fact, they’re first-choice medication options for treating high blood pressure (hypertension). Lowering your blood pressure relieves stress on your heart, brain, and kidneys. And over time, these critical organs are less likely to become damaged.
All ACE inhibitors can treat hypertension. But they treat several other conditions, including:
Kidney problems caused by diabetes (diabetic nephropathy)
Chronic kidney disease in people with protein in the urine
Risk of death after a heart attack
Risk of major health events, like heart attack or stroke, in people who are at high risk
Like hypertension, ACE inhibitors are first-choice medications for several of these conditions. This includes diabetic nephropathy and certain types of heart failure. But keep in mind that each ACE inhibitor isn’t FDA approved for all these conditions. This means they’re used “off-label” in some cases.
How do ACE inhibitors work?
ACE inhibitors work by blocking the enzyme ACE. This has several effects because ACE is found throughout your body, including in the lungs, heart, and kidneys. ACE’s main purpose is to make angiotensin II. This is a hormone that regulates blood pressure and fluid balance in the body.
There are several things that occur to create angiotensin II:
First, the hormone angiotensin is formed in your liver and released into your blood.
Then, an enzyme from the kidneys (renin) changes angiotensin into angiotensin I. Angiotensin I is inactive (it doesn’t have a known effect on the body).
Finally, ACE helps turn angiotensin I to angiotensin II. This is the active form of angiotensin.
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Below, we’ll look at how ACE inhibitors’ ability to block angiotensin II helps treat several health conditions.
Hypertension
When angiotensin II is released, it increases blood pressure. It does this in several ways, such as:
Constricting (narrowing) blood vessels, making it harder for blood to flow throughout the body
Increasing aldosterone, a hormone that causes your kidneys to hold on to salt and water
Influencing the kidneys directly to reduce blood flow and hold on to salt and water
By blocking angiotensin II, ACE inhibitors widen your blood vessels, decrease aldosterone levels, and improve blood flow in the kidneys. They also reduce the amount of fluid and sodium your body holds on to.
All ACE inhibitors work similarly. So they’re expected to have about the same blood-pressure-lowering effect. They’re typically prescribed alone to treat hypertension unless they don’t lower your blood pressure enough. In this case, you may need additional medications.
Good to know: Renin, angiotensin II, and aldosterone are the major hormones in the renin-angiotensin-aldosterone system (RAAS). The RAAS system helps regulate our salt and water balance and maintain blood pressure. When the RAAS system is overactive, health issues like hypertension can arise.
Heart failure
ACE inhibitors can prevent and treat heart failure in some people. Lowering blood pressure and fluid levels in the body makes it so your heart doesn’t have to work as hard. ACE inhibitors also prevent heart muscle damage by lowering levels of angiotensin and aldosterone.
It’s important to note that ACE inhibitors aren’t prescribed alone in heart failure. They’re part of a treatment plan that usually includes other medications.
Kidney disease
ACE inhibitors can protect your kidneys. One way they do this is by lowering blood pressure, which lowers the stress on your kidneys. But even if you don’t have high blood pressure, ACE inhibitors may help your kidneys, especially if you have protein in your urine or if you have diabetes.
Though it’s rare, ACE inhibitors can also cause kidney damage. It’s more likely if you have certain health conditions, like renal artery stenosis. Your nephrologist (kidney specialist) will monitor your kidney function while you’re taking an ACE inhibitor.
How do you know if your ACE inhibitor is working?
If you’re taking your ACE inhibitor for hypertension, your prescriber may ask you to check your blood pressure at home. Your blood pressure readings will tell you if it’s working. If your blood pressure is still high, they may suggest increasing your dose or adding another blood pressure medication.
For other conditions, like kidney disease and diabetes, it’s harder to notice if your ACE inhibitor is working. But keep in mind that the benefits of taking an ACE inhibitor are long term. It’s like brushing your teeth. You may not notice the benefits on any given day, but it helps prevent dental problems years down the line.
Even if you don’t notice beneficial effects of your ACE inhibitor, taking it consistently over a long period of time is where the true benefits exist. But if your ACE inhibitor is causing side effects that are bothersome, your prescriber can work with you to find a different medication that works well and causes fewer side effects.
Good to know: Although some people need medications to lower blood pressure, dietary and lifestyle changes are also vital. But there isn’t one right way to eat or stay active. Finding healthy lifestyle habits and a dietary pattern that you can stick to is most important.
How are ACE inhibitors different from other blood pressure medications?
Besides ACE inhibitors, three other groups of blood pressure medications are considered first-choice options for hypertension in most people. The other three medication groups are:
Thiazide diuretics, such as hydrochlorothiazide (Microzide)
Calcium channel blockers (CCBs), such as amlodipine (Norvasc)
Angiotensin II receptor blockers (ARBs), such as losartan (Cozaar)
ARBs are most similar to ACE inhibitors and work just as well. But because they’re so similar, ARBs and ACE inhibitors aren’t used together. If you need a second blood pressure medication, ACE inhibitors are often paired with a thiazide diuretic or a CCB. In fact, several combination products containing two or more blood pressure medications are available.
There are several situations in which another blood pressure medication may be preferred over an ACE inhibitor. A few examples include:
If ACE inhibitors cause unacceptable side effects: Like all medications, ACE inhibitors have side effects. For example, ACE inhibitors can cause cough, angioedema (swelling of the face, neck, and mouth), and hyperkalemia (high potassium levels). If you’re experiencing these side effects, your prescriber may recommend another blood pressure medication.
If you’re pregnant or planning on becoming pregnant: Your prescriber won’t recommend an ACE inhibitor (or an ARB) in these situations. They can cause birth defects. Safer hypertension treatment options are available to treat high blood pressure during pregnancy.
If you have certain health conditions: ACE inhibitors should be avoided with certain health conditions. For example, if you have hereditary angioedema, you shouldn’t take ACE inhibitors. And people with aortic valve stenosis should be more careful when using ACE inhibitors.
The bottom line
Angiotensin-converting enzyme (ACE) inhibitors have been used to treat high blood pressure for generations. ACE inhibitors also do several other things. For example, they’re prescribed to help manage heart failure and treat kidney disease with and without diabetes.
ACE inhibitors’ mechanism of action is to block an enzyme (ACE) that’s responsible for making angiotensin II. Under normal conditions, angiotensin II regulates blood pressure and the balance of salt and water in your body. But when it’s overactive, it can increase blood pressure and cause other negative health effects.
ACE inhibitors widen your blood vessels, which decreases blood pressure. ACE inhibitors also have several other benefits, including positive heart and kidney effects.
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