Angiotensin-converting enzyme (ACE) inhibitors are a class of medications primarily used to manage various cardiovascular conditions. They influence specific processes within the body that regulate blood pressure and fluid balance. These medications help relax blood vessels and reduce the heart’s workload, contributing to improved heart and kidney health.
The Body’s Blood Pressure Regulators
The body possesses a complex system to maintain stable blood pressure and fluid balance, known as the Renin-Angiotensin-Aldosterone System (RAAS). This system involves hormones and enzymes that respond to changes in blood pressure or fluid levels. When blood pressure drops, the kidneys release an enzyme called renin.
Renin then acts on a protein produced by the liver, called angiotensinogen, converting it into angiotensin I. Angiotensin I is largely inactive, but it serves as a precursor for a more potent substance. As blood flows through the lungs and other tissues, angiotensin I encounters angiotensin-converting enzyme (ACE).
The ACE enzyme transforms angiotensin I into angiotensin II, a powerful hormone. Angiotensin II causes blood vessels to narrow, a process called vasoconstriction, which increases blood pressure. It also stimulates the adrenal glands to release aldosterone, a hormone that signals the kidneys to retain more sodium and water, further increasing blood volume and blood pressure.
How ACE Inhibitors Work
ACE inhibitors specifically target the Angiotensin-Converting Enzyme within the RAAS. These medications bind to the zinc ion of the ACE enzyme, which effectively blocks its ability to convert angiotensin I into angiotensin II. This inhibition reduces the overall amount of angiotensin II in the bloodstream.
Without sufficient angiotensin II, blood vessels relax and widen, a process called vasodilation, lowering blood pressure. This widening of blood vessels decreases the resistance against which the heart has to pump, thereby reducing its workload.
Lowered angiotensin II levels also lead to decreased production of aldosterone. This results in the kidneys excreting more sodium and water, which reduces the body’s fluid volume and contributes to lower blood pressure. Additionally, ACE inhibitors can increase levels of bradykinin, a substance that further promotes vasodilation and helps relax blood vessels.
Conditions Treated with ACE Inhibitors
ACE inhibitors are widely prescribed for various medical conditions. One of their most common uses is in treating hypertension. By promoting vasodilation and reducing fluid retention, these medications effectively lower elevated blood pressure, which lessens the strain on the heart and blood vessels.
They are also a standard treatment for heart failure, a condition where the heart cannot pump enough blood. ACE inhibitors help by reducing the heart’s workload through vasodilation and decreasing blood volume, which allows the weakened heart to pump more efficiently.
Furthermore, ACE inhibitors are beneficial for individuals with diabetic kidney disease and other forms of chronic kidney disease. They help protect the kidneys by reducing pressure within the kidney’s filtering units and decreasing the amount of protein in the urine. These medications can help slow the progression of kidney disease, particularly in people with diabetes.
Important Considerations When Taking ACE Inhibitors
Patients taking ACE inhibitors should be aware of potential side effects and interactions. A common side effect is a persistent, dry cough, thought to be due to increased bradykinin levels. Other side effects include dizziness, headaches, and a metallic or altered taste.
More serious, though rare, side effects can occur. These include angioedema, a rapid swelling of the face, lips, tongue, or throat. Another concern is hyperkalemia, elevated potassium in the blood, which can be risky for individuals with kidney issues or those taking potassium supplements. Kidney dysfunction can also rarely worsen, especially with existing severe kidney disease or narrowed kidney arteries.
ACE inhibitors are not prescribed during pregnancy due to potential risks to the fetus. They also interact with certain medications; for instance, nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce their effectiveness and potentially affect kidney function. Combinations with angiotensin receptor blockers (ARBs) or direct renin inhibitors are avoided due to increased risks of low blood pressure, hyperkalemia, and kidney impairment. Regular monitoring of blood pressure, kidney function, and potassium levels through blood tests is recommended to ensure safety and effectiveness.