Angiotensin-Converting Enzyme (ACE) inhibitors are prescription medicines used to treat conditions related to the cardiovascular system. These medications lower blood pressure and are prescribed for various heart and kidney conditions. By interfering with a specific hormonal process, they relax blood vessels and reduce the heart’s workload.
How ACEIs Work
ACE inhibitors function by interrupting a sequence of events in the body known as the Renin-Angiotensin-Aldosterone System (RAAS). This system is a complex chain reaction that regulates blood pressure. When blood pressure drops, the kidneys release an enzyme called renin, which acts on a protein from the liver to produce angiotensin I, a substance that must be converted into a more active form.
The angiotensin-converting enzyme, found primarily in the lungs and blood vessel linings, transforms angiotensin I into angiotensin II. Angiotensin II is a potent substance that constricts, or narrows, blood vessels throughout the body, which causes blood pressure to rise. It also stimulates the release of a hormone called aldosterone, which signals the kidneys to retain salt and water, further increasing blood volume and pressure.
ACE inhibitors work by blocking the action of the angiotensin-converting enzyme. This blockage prevents the formation of angiotensin II, leading to the relaxation and widening of blood vessels, a state known as vasodilation. With less angiotensin II circulating, aldosterone levels also decrease, allowing the kidneys to excrete more sodium and water. The combined effect of relaxed blood vessels and reduced blood volume lowers blood pressure and eases the strain on the heart.
Medical Uses for ACEIs
The primary use for ACE inhibitors is managing high blood pressure, also known as hypertension. This action helps prevent the long-term damage that sustained high blood pressure can cause to arteries and organs.
These medications also treat heart failure, a condition where the heart cannot pump enough blood to meet the body’s needs. The reduced workload on the heart helps improve the efficiency of a weakened heart muscle and can alleviate symptoms like shortness of breath and fatigue.
Following a heart attack, ACE inhibitors are often prescribed to improve survival and prevent future cardiac events. They also protect the kidneys, particularly in individuals with diabetes or chronic kidney disease, by lowering the pressure inside the kidneys’ filtering units.
Common Types of ACE Inhibitors
A variety of ACE inhibitors are available, and the choice depends on factors like how long the drug’s effects last. Some are short-acting and may be taken more than once a day, while others are long-acting and require a single daily dose. Healthcare providers select the most suitable option based on a person’s health needs.
Commonly prescribed ACE inhibitors include:
- Lisinopril (Zestril, Prinivil)
- Enalapril (Vasotec)
- Ramipril (Altace)
- Benazepril (Lotensin)
- Captopril
- Perindopril
While the core mechanism of these drugs is the same, they differ in their chemical structure and how the body processes them.
Potential Side Effects
While many people tolerate ACE inhibitors well, side effects can occur. The most distinctive is a persistent, dry cough, thought to be caused by the medication’s effect on substances in the lungs like bradykinin. Dizziness or lightheadedness, particularly after the initial doses, can also happen as the body adjusts to lower blood pressure. Some individuals may also experience fatigue or headaches.
Less common but more serious side effects require prompt medical attention. One is angioedema, a rapid swelling of the skin, including the face, lips, and tongue, which can affect breathing. Another is an increase in blood potassium levels, known as hyperkalemia, because the medication reduces the body’s ability to excrete it. ACE inhibitors can also cause a temporary worsening of kidney function.
Patients are advised to communicate with their healthcare provider about any side effects they experience. Abruptly stopping the medication without medical guidance is not recommended, as it can cause a rapid increase in blood pressure.
Important Considerations and Drug Interactions
Certain precautions are necessary when taking ACE inhibitors. These medications are not recommended during pregnancy as they have been linked to birth defects. Anyone who is pregnant or planning to become pregnant should discuss alternative treatments with their doctor. Regular monitoring through blood tests is also standard to check on kidney function and potassium levels.
Drug interactions can alter the effectiveness of ACE inhibitors or increase the risk of adverse effects. Nonsteroidal anti-inflammatory drugs (NSAIDs), like ibuprofen and naproxen, can reduce their blood pressure-lowering effects. Taking potassium supplements or salt substitutes containing potassium can elevate the risk of high potassium levels.
ACE inhibitors may be prescribed with other blood pressure medications, like diuretics or calcium channel blockers, for a greater effect. However, they should not be taken with certain drug classes, such as angiotensin receptor blockers (ARBs) or direct renin inhibitors. This combination can increase risks without providing additional benefits.