How Does Lisinopril work?

Published February 5th, 2020 by Chris Riley
Fact Checked by
Chris Riley
Updated Date: Jul 7th, 2022

Drugs within all of these classes are commonly prescribed for cardiovascular problems and some of these names might be familiar to you. Each of these classes of drugs has its own target within the cardiovascular system and uses a distinct mechanism to bring about the desired effect, which in the case of hypertension is lowered blood pressure. Drugs from each class can be prescribed on their own, or they are often given in combination with each other for the maximum efficacy. 

Lisinopril is one of the most commonly prescribed drugs annually in the United States, and it belongs to the ACE Inhibitors family of cardiovascular drugs. What is Lisinopril and exactly what is lisinopril used for?   It is a first-line treatment recommended for bringing down hypertension. It is also prescribed to increase the chance of survival after a heart attack, and for treatment of congestive heart failure. Less common, but also important, uses for lisinopril include protection against kidney disease in diabetic patients. 

The ACE inhibitors revolutionized the treatment of cardiovascular diseases since their discovery in the early 1980s, so this class of drugs has been around for a long time. They are known for being effective, mostly safe with regular monitoring and are generally well tolerated by patients. Current research is ongoing to explore the benefits that lisinopril tablets can have on other diseases. 

How exactly does it work?

We know a lot about the way ACE inhibitors, like lisinopril, work to treat cardiovascular problems. ACE stands for Angiotensin Converting Enzyme and it belongs to the Renin-Angiotensin-Aldosterone system (RAAS) in the body. ACE inhibitors block the action of Angiotensin II, a powerful vasoconstrictor. Vasoconstriction is the narrowing of blood vessels that increases blood pressure. The RAAS hormonal system is critically responsible for maintaining blood pressure by regulating fluid balance. There are three hormones involved in this system from which it gets its name- renin, angiotensin, and aldosterone. Normally in the body, Angiotensin II is released by the action of the RAAS system. This happens in several sequential steps. First, renin is secreted into the bloodstream by cells in the kidney. Next, renin converts an inactive form of Angiotensin I into a shorter form. This shorter form of Angiotensin I is then converted into Angiotensin II by the Angiotensin Converting Enzyme, or ACE. Angiotensin II is the biologically active substance that causes muscles in the arteries to constrict resulting in their narrowing. It does this by binding to another protein named the AT1 receptors. ACE inhibitors, like lisinopril, block the action of ACE to prevent the conversion of Angiotensin I into the active Angiotensin II. When this happens, Angiotensin II can no longer bind to the AT1 receptors and this prevents the arteries from narrowing. In the absence of this narrowing, blood can flow freely through the arteries and blood pressure is reduced. 

The way lisinopril works to reduce blood pressure is also the reason why it is prescribed for patients recovering from a heart attack. During a heart attack, the heart tissue is weakened and damaged. By lowering blood pressure and allowing blood to flow freely through the arteries, the heart does not have to work as hard to pump blood, so the chances of survival are increased. Overall, lisinopril acts by decreasing constriction of arteries, which in turn reduces blood pressure, and lightens the workload of the heart so that cardiac output can be less. 

Lisinopril is also used for the treatment of chronic kidney disease in diabetic patients. Diabetes increases the risk of renal toxicity due to high blood glucose levels and it is increasingly becoming the leading cause for renal failure worldwide. In diabetes, the RAAS in the kidneys is activated. Using lisinopril to inhibit the RAAS by blocking the action of Angiotensin II has been proven to assist with kidney problems by slowing the loss of kidney function in these patients. Diabetic patients also excrete more proteins in their urine than normal because the kidneys cannot filter properly- a condition called ‘proteinuria’.  Lisinopril tablets can protect patients from this abnormal occurrence by reducing the number of proteins lost in urine. 

The RAAS system has proven to be a remarkable drug target for the treatment of hypertension and other cardiovascular-related problems. The development of drugs like lisinopril that can target the RAAS would not have been possible without complete knowledge of how this hormonal system works in regulating circulation.  Since we know a lot about the mechanism lisinopril uses, we can also understand how long it takes to work in most individuals. 

Unlike many other ACE inhibitors, lisinopril is already in its active form. Other common hypertension drugs, like enalapril, are formulated in a prodrug form. Prodrugs are inactive until they are swallowed. They are then metabolized in the body to become active. In the case of enalapril, once swallowed it is hydrolyzed into the active ACE inhibitor enalaprilat by the liver. This metabolized drug is what is excreted from the body. Since lisinopril is already in its active form, it is not metabolized by the liver and is directly excreted by the kidneys. Due to this, the possibility of renal toxicity can occur when taking this drug. Regular monitoring of kidney function has been recommended for individuals that are susceptible to this. 

But, how long does lisinopril take to work? Once taken, lisinopril usually takes a few hours to start working. The half-life of a drug helps us understand how long a drug stays in the body. The elimination half-life is the amount of time it takes for a drug to reach half its amount in the body. Lisinopril has a half-life of 12 hours and it will take about three days for the body to be completely cleared of lisinopril once taken. 

Usually, lisinopril is prescribed alone or in combination with other drugs depending on its indicated use. Once you are prescribed it and learn when to take lisinopril, it may take a few weeks before you get the full benefit of taking this medication. If this happens, don't change the dose recommended by your doctor.  Reduction in hypertension may not be accompanied by a change in symptoms immediately, but it is important to keep taking the drug to maintain blood pressure at a normal level to reduce the risk of serious complications of high blood pressure like a heart attack.  Before you begin taking lisinopril, be sure you are aware of any side effects or ingredients that may cause symptoms of an allergic reaction.

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How to save on buying Lisinopril

Lisinopril is also known by the brand names Prinivil and Zestril. If you are prescribed lisinopril for a medical condition, you can take your prescription to any pharmacy to pick it up. Lisinopril is often prescribed long-term which can be a concern to patients who have to cope with the cost of the drug. Drug coupons for lisinopril can help you save on costs, even if you have insurance. These coupons, available through USA Rx, can be presented to your pharmacist to find out how much you can save. If you are taking more than one medication, you can save even more by signing up for a free pharmacy discount card by USA Rx. Signing up for the card takes just a few minutes and can be done online. The pharmacy discount card can be presented at any pharmacy to save on all FDA-approved drugs, including lisinopril. 

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