How Does Quinapril Work? (Accupril) Uses, Side Effects, Precautions

How Does Quinapril Work?

How Does Quinapril Work?

Quinapril is a type of drug called an ACE inhibitor that works by stopping the production of the angiotensin II hormone, which usually causes the blood pressure to increase in the body. When quinapril stops the hormone from being formed as usual, the blood pressure decreases, which can help in the treatment of hypertension.

If you or someone you know needs to take quinapril to help lower your blood pressure or improve your heart health, most of the information that you’ll need can be found here.

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Brand Names and Doses

Brand Dose IconQuinapril is the generic name, which is the active drug found in the medication. There are several different brand names that all contain the same drug:

  • Accupril
  • Aquinafil
  • Filpril
  • Qpril

All of these medications have the same active ingredient and work the same way in your body. They’ve just got different names because they are manufactured by different companies. There are three different doses of each brand available: 5mg, 10mg and 20mg.

Quinapril is also available in a combination medication that also has a dose of hydrochlorothiazide in each pill. Accuretic is the brand name of the combination and includes a dose of 10mg quinapril/12.5 mg hydrochlorothiazide OR 20mg quinapril/12.5 mg hydrochlorothiazide.

What type of drug is it?

Drug Type IconQuinapril is a type of drug called an angiotensin-converting enzyme (ACE) inhibitor, a group of medications that work in a similar way to lower blood pressure. Other medicines in the same class are:

How does it work?

How it works IconQuinapril and other ACE inhibitor drugs work to lower blood pressure by stopping an enzyme in the body from converting angiotensin I to angiotensin II. Angiotensin II is the active form, which usually helps to keep the blood pressure higher when it’s too low by tightening the blood vessels and increasing the amount of blood travelling through them.

When you take quinapril, you don’t have as much angiotensin II in your body and it can’t work its effect as usual to increase the blood pressure. This is what happens:

  • The muscles around your blood vessels relax, creating more room for the blood to pass through.
  • Your kidneys reabsorb less water and you excrete more in your urine, which means you will have less blood in your blood system.

This means that you will have less blood pumping around blood vessels that are roomier than usual. If you think of it like a plumbing system, that means there is going to be less pressure on your cardiovascular system and help your heart.

Side Effects

Side Effects IconACE inhibitors have a broad action on the body and, as a result, there are several side effects that can occur when you take quinapril. The most important ones are explained below, but you should check the medicine information leaflet for the complete list.

Low blood pressure (hypotension)

The most common side effects happen because it’s working too well and you end up with low blood pressure. You might notice symptoms of:

  • Headache
  • Tiredness
  • Dizziness
  • Flushing

This is most common when you first start taking quinapril or if your dose has recently increased, which usually gets better in a few days as your body gets used to the drug. If you still notice these effects after more than a week, your blood pressure might be low because you’re taking a dose that is too high. You can test your blood pressure to make sure (this is free at most pharmacies) and you can talk to your doctor about lowering the dose.

Excess Potassium (Hyperkalaemia)

Quinapril causes more water to be excreted in the urine that usual, which can upset the balance of potassium and other salts in your body. Less potassium is excreted and it can build-up in your blood and body, causing symptoms of tiredness and muscle weakness.

The best way to check if you have high potassium levels is to take a simple blood test, so simply have a chat with your doctor if you think you might have hyperkalemia.


Quinapril can cause some people to get a dry cough, which can be quite frustrating as it does not seem to go away. If you experience a cough and it annoys you, you can talk to your doctor about alternative medications like an angiotensin II channel blocker.


Cautions IconThere are a couple of things you should be aware of before you start taking quinapril, as they can have serious consequences for some people.


Rarely, quinapril can cause swelling of the mouth and throat called angioedema, which is serious because it can stop you from breathing as normal.

If you have suffered from angioedema before, you should not take quinapril because you are more likely to experience it again. If you are taking the medication and you notice swelling around your mouth and face, see a doctor immediately.

Renal Impairment

Quinapril puts extra pressure on the kidneys and increases the risk of renal impairment, particularly when used with other medications, such as NSAIDS and diuretics.  If you have poor kidney function, it is not likely to be the best choice of drug for you.

Stopping Suddenly

Quinapril should be taken every day to manage high blood pressure over the long-term. If you suddenly stop taking it, the amount of angiotensin II in your body will increase once again and cause more blood to push through smaller blood vessels. Your hypertension might be even worse because of the sudden change, called rebound hypertension.

Instead, you should gradually reduce the dose over a few weeks when you want to stop taking quinapril. If you take the 20mg dose usually, decrease it to 10mg and then 5mg daily until your body feels normal and you can stop completely.

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Drug Interactions

Drug Interactions IconLithium + Quinapril Interaction

Quinapril can decrease the amount of lithium that is excreted from the body, leading to high concentrations and increased risk of side effects. The dose of lithium can be reduced to manage this, or a different antihypertensive medication can be used.

Loop Diuretic + Quinapril Interaction

Taking a loop diuretic drug and quinapril together increases the risk of blood pressure that is too low, particularly for the first few doses. You may need a lower dose or to stop taking the loop diuretic for a few days when beginning quinapril. Using both may also increase risk of renal impairment.

NSAID + Quinapril Interaction

NSAIDs and quinapril can sometimes be used together in young otherwise healthy patients, but it might not work as well to reduce your blood pressure.

Thiazide Diuretic + Quinapril Interaction

Taking a thiazide diuretic and quinapril together increases the risk of blood pressure that is too low, particularly for the first few doses, and may increase the risk of renal impairment. Using a lower dose is okay for some people but the combination is not recommended for others – it depends on your individual situation.

Pregnancy and Breastfeeding

Pregnancy IconYou should not take quinapril if you are pregnant, breastfeeding or planning to become pregnant in the future. Doses in the first trimester may cause birth defects and later in the pregnancy can lead to renal dysfunction of the baby.

You can take quinapril when you are breastfeeding. Very small amounts may be excreted in the breast milk, but no side effects have been reported. It is best to monitor for possible signs of low blood pressure in your baby, however, such as tiredness and irritability.

About the author


Yolanda is a passionate medical writer who loves to help people understand how health and different treatments work. After graduating in Pharmacy in Australia, she moved to Italy to study the Mediterranean way of life and continue learning about health and medicine.

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