What is the mechanism of Lisinopril?

Lisinopril is a widely used medication primarily prescribed for the treatment of high blood pressure (hypertension) and heart failure. It also helps to improve survival rates after a heart attack. To understand its mechanism of action, it is essential to delve into how it interacts with the body's biological systems.

Lisinopril belongs to a class of drugs known as angiotensin-converting enzyme (ACE) inhibitors. ACE inhibitors work by targeting the renin-angiotensin-aldosterone system (RAAS), which plays a crucial role in regulating blood pressure and fluid balance.

The process begins at the kidneys. When blood pressure falls or when there is a reduction in sodium chloride delivery to the distal tubule of the nephron, the kidneys release an enzyme called renin into the bloodstream. Renin acts on a protein called angiotensinogen, which is produced by the liver, converting it into angiotensin I. Angiotensin I is relatively inactive, but it serves as a precursor to a more potent substance.

This is where the angiotensin-converting enzyme (ACE) comes into play. ACE, predominantly found in the lungs and endothelial cells of blood vessels, converts angiotensin I to angiotensin II. Angiotensin II is a potent vasoconstrictor, meaning it narrows blood vessels, which increases blood pressure. Additionally, angiotensin II stimulates the release of aldosterone from the adrenal glands. Aldosterone promotes the retention of sodium and water by the kidneys, further increasing blood volume and, consequently, blood pressure.

Lisinopril exerts its therapeutic effects by inhibiting the activity of ACE. By blocking ACE, lisinopril prevents the conversion of angiotensin I to angiotensin II. As a result, the levels of angiotensin II decrease, leading to several beneficial effects:

1. Vasodilation: With less angiotensin II to constrict blood vessels, the vessels relax and widen. This vasodilation reduces the resistance against which the heart has to pump, lowering blood pressure.

2. Decreased Aldosterone Secretion: By reducing the production of angiotensin II, lisinopril also decreases the secretion of aldosterone. This leads to less sodium and water retention by the kidneys, reducing blood volume and further aiding in lowering blood pressure.

3. Reduced Cardiac Workload: Lower blood pressure means that the heart does not have to work as hard to pump blood, which is particularly beneficial for patients with heart failure. This reduction in workload helps prevent further damage to the heart.

4. Renal Protection: By decreasing the pressure within the arterioles of the kidneys, lisinopril can help protect renal function, which is especially important for patients with diabetes or chronic kidney disease.

In summary, lisinopril’s mechanism of action revolves around its ability to inhibit the angiotensin-converting enzyme, which prevents the formation of angiotensin II. This leads to vasodilation, reduced aldosterone secretion, decreased blood volume, and ultimately, lower blood pressure. These combined effects not only help manage hypertension but also contribute to the treatment of heart failure and improve outcomes after a heart attack.