What's the Role Of Nitrates (Nitroglycerin) In Treating Coronary Artery Disease?

Nitrates are a class of drugs that have been used to treat angina for the past century. In modern medicine, nitrates can manage both chronic and acute angina by serving during pain episodes. Nitrates are available in different forms, including oral spray, patches, and pills.

What is angina?

Angina is one of the clearest symptoms and consequences of coronary artery disease. It’s the medical term used to describe chest pain, which can be stable and unstable:

• Stable angina has a predictable pattern, which means that you can predict when it will occur. It typically shows up when the heart is overworked, mostly when you’re performing physical activities. All episodes of stable angina typically have the same pain intensity and generally last less than five minutes. It usually disappears once you get some rest or take pills prescribed by your doctor.
• Unstable angina is considered a medical emergency and can occur at any time, without having a predictable pattern. People with unstable angina will experience pain even when they’re resting, and episodes can last way longer than those of stable angina (maybe even more than half an hour). It doesn’t always disappear when you’re taking angina medication or resting and can also be a sign of a heart attack.

The role of nitrates

Nitrates are drugs that cause the blood vessels to dilate, acting on the coronary arteries, but also on other arteries inside the body. Coronary artery disease can put a lot of strain on the heart because when the arteries are narrow or blocked, the heart has to work overtime to pump the blood it needs. The immediate consequence is chest pain.

Because nitrates help dilate the blood vessels, blood can circulate inside the arteries with a more normal flow and doesn’t force the heart to work too much.

There’s one important thing to keep in mind about coronary artery disease and nitrates: when atherosclerotic plaque formations are restricting blood flow, the coronary arteries will normally dilate, so that more blood can flow through them. In this case, nitrate drugs can’t really cause that much dilation.

However, people who have Prinzmetal angina benefit from nitrates way more. As you recall, this type of angina is caused by a coronary artery spasm.

What do you need to know about treatment with nitrates?

It is generally administered when someone is experiencing angina as a result of physical activity, as it can provide pain relief in a matter of minutes. More importantly, sublingual angina taken before performing a strenuous exercise can prevent angina pain altogether. It takes about two minutes for this type of nitrate to start its vasodilating actions, and the effect can last about half an hour.

Nitroglycerin comes in a spray form as well, and it’s another efficient way of delivering a quick nitrate dose. Both of these forms of nitroglycerin should be carried with you at all times and are called short-acting nitrates.

There are also long-acting nitrates, which are an alternative to beta blockers prescribed when these aren’t efficient or tolerated. This type of nitrates comes in pill or skin patch form. Oral nitrates take about 30 minutes to start dilating the blood vessels, but their effects can last for up to six hours. Nitroglycerin patches will deliver the required dose of nitrates through the skin and have an effect that lasts up to 14 hours.

Nitrates: Precautions patients should take

Long-acting nitrates, while efficient, have been known to cause tolerance. That means that when a drug is administered to the same person for too long, the body kind of develops an immunity to it, so the medication becomes less and less effective over time.

In this particular case, it means that blood vessels that have been constantly exposed to the dilating effects of nitroglycerin will eventually stop dilating when you’re taking the drug. The best way to prevent that from happening is to regulate the nitrate schedule to include nitrate-free intervals. For example, you can take a break from oral and nitrate patches for eight to 12 continuous hours per day, but still use them in the remaining time.

However, if you often have nocturnal episodes of angina, the nitrate-free intervals might need to be scheduled while you are awake. Taking them at night, during an episode, will help you sleep, so you can’t make any compromises here.

Nitrate therapy should be avoided if you have hypertrophic cardiomyopathy. These drugs are also known to interact with erectile dysfunction medication (such as Viagra), by causing a severe drop in blood pressure. Those who have migraine-related headaches will also not respond well to nitrate treatment.

Nitrates can come with a few side effects, which include flushing and headaches. If you’re also experiencing a drop in blood pressure, you may also feel lightheaded.

Conclusion

Nitroglycerin is a type of nitrate that dilates the blood vessels to allow blood to flow freely inside the coronary arteries. People who have coronary artery disease have a restricted blood supply to the heart, so this vasodilator drug leads the arteries to become more relaxed and the heart doesn’t have to work that hard.