Types of Vasodilator Drugs

It's more common to classify vasodilator drugs based on the way they work to widen blood vessels. Some act directly on blood vessels, making them relax and become wider. Others inhibit specific actions of the body that would cause the blood vessels to tighten and become narrower.

  • ACE inhibitors (angiotensin-converting enzyme inhibitors) work by blocking the body's production of a chemical called angiotensin II. This chemical causes blood vessels to narrow -- so, blocking its production allows blood vessels to become wider. As a result, more blood can flow into the vessels, and the heart's workload is decreased. For heart failure patients, doctors prescribe ACE inhibitors more often than any other type of vasodilator. In patients with chronic heart failure, ACE inhibitors not only help relieve symptoms but also slow disease progression and increase life span. ACE inhibitors also increase blood flow to the kidneys, which helps the kidneys excrete more sodium and water and helps reduce fluid overload, a common symptom of heart failure.
  • Angiotensin II receptor blockers achieve the same effect as ACE inhibitors, but they work in a different way. Instead of preventing the production of angiotensin II, they block it from being able to act in the muscles that line the blood vessels. So they indirectly decrease the heart's workload.
  • Alpha blockers reduce the workload of the heart by blocking certain chemicals from acting.
junk food plate
Robert Sullivan/AFP/Getty Images
This plate of food would definitely not be a part of a
heart-healthy diet to lower blood pressure.
  • Calcium channel blockers reduce the workload of the heart by blocking signals that tell blood vessels in the heart to tighten They have a direct slowing effect on the heart muscle.
  • Nitrates work by dilating the veins of the body and by working directly on the muscles of the heart's blood vessels, causing them to relax and increasing the flow of oxygen-rich blood to the heart.
  • Thiazide diuretics are one of four types of diuretic drugs. These medications increase the kidney's production of urine, thus removing fluid and minerals (including sodium) from the body. Low-dose thiazide diuretics also work as vasodilators.
  • Central adrenergic inhibitors interfere with signals from the brain that tell blood vessels to tighten. This class of vasodilator drugs is also used for other conditions, including panic attacks and migraine headaches.

Many vasodilator drugs have other effects that can sometimes provide additional benefits. For example, some calcium channel blockers not only dilate blood vessels but also lessen the heart's mechanical and electrical functions, which in turn can enhance their blood-pressure-lowering action and may also help regulate arrhythmias (irregular heart rhythms).

Doctors decide which type of vasodilator drug to prescribe based on medical history, current symptoms and other medical conditions. Vasodilator drugs are rarely used alone -- they're usually prescribed in combination with other types of blood pressure drugs.

Once people who have high blood pressure begin taking vasodilator drugs, they generally need to keep taking them for the rest of their lives. Without these medicines, they would be at risk of developing serious health problems. And medicine alone may not be enough. People who are taking vasodilator drugs are usually encouraged by their doctors to make healthy lifestyle changes, like eating a heart-healthy diet, getting regular exercise and practicing stress-management techniques.