What is an Angiotensin Receptor Blocker?

An angiotensin receptor blocker is a classification of oral prescription medication. Doctors commonly prescribe this type of drug to treat hypertension, congestive heart failure, and kidney problems caused by diabetes. The drug works by blocking certain chemicals from being released in the body, thus helping with blood flow and urination.

The human body produces a chemical known as angiotensin II. This substance causes the blood vessels to narrow and keep blood circulating in the body. In most people, the effects of angiotensin II are beneficial and necessary for the cardiovascular system to function properly.

Hypertension or high blood pressure occurs when blood moving through the body meets too much resistance, making the heart work harder to maintain proper circulation throughout the body. Over time, hypertension can cause the blood vessels that carry blood to the heart to thicken and harden, posing a risk for heart attack, heart disease, or stroke. Generally, an angiotensin receptor blocker has the potential to prevent this damage.

When patients take an angiotensin receptor blocker, the medication binds to spots inside the blood vessels meant to interact with angiotensin II. This prevents the chemical from reaching these regions. As a result of the drug, angiotensin becomes unable to exert its effects upon the body. The blood vessels remain relaxed and wide, allowing blood to flow through the body easily. Ultimately, blood pressure levels decrease, and stress on the heart also lessens due to the angiotensin receptor blocker.

Some patients with hypertension develop congestive heart failure — the inability of the heart to pump blood properly throughout the body. The condition can also occur from a bacterial infection in the heart, lung diseases such as emphysema, dysfunction of the thyroid gland, or severe anemia. Whatever the underlying cause of the condition, the effects of an angiotensin receptor blocker improve circulations. Patients treated with the medication experience relief from the symptoms of congestive heart failure such as edema and shortness of breath.

An angiotensin receptor blocker may also find use in improving kidney function in patients suffering from diabetic nephropathy. This condition arises in patients with diabetes after the kidneys endure exposure to high blood sugar levels for prolonged periods of time. The sugar causes damage to the kidneys, making them unable to remove excess fluid from the body through the production of urine. In severe cases, the kidneys shut down completely, and patients require dialysis to survive.

In addition to causing the narrowing of blood vessels, angiotensin II also causes the body to release another chemical known as aldosterone. This chemical gives signals to the kidneys to retain fluid and sodium rather than departing from the body as urine. When patients with diabetic nephropathy take an angiotensin receptor blocker, the medication prevents angiotensin II from triggering the secretion of aldosterone. Without the effects of this chemical, the kidneys produce more urine.

Pharmaceutical companies may manufacture an angiotensin receptor blocker under a variety of names, including candesartan, valsartan, irbesartan, losartan, olmesartan, and telmisartan. Doctors sometimes refer to the class of drugs as sartans. Because of the way they function, angiotensin receptor blockers are sometimes called angiotensin II receptor antagonists, or AT1-receptor antagonists for short.