How Do Nitrates Work? (Nitroglycerin)

Summary

This video explains how nitrates work, focusing on their role in treating angina pectoris, a type of chest pain caused by an imbalance between oxygen supply and demand in the heart. It discusses different types of nitrates, including nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate, their mechanisms, dosing, and when they are used for acute versus chronic angina. The video also covers potential side effects like headaches and dizziness, drug interactions, particularly with PDE5 inhibitors, and the importance of a nitrate-free interval to prevent tolerance build-up.

Takeaways

• 💡 Angina pectoris is chest pain caused by an imbalance between the oxygen supply and demand of the heart.
• 🏃 Running increases the oxygen demand for the heart and the entire body, which can lead to ischemia if the supply can't meet the demand.
• 💊 Nitrates, such as nitroglycerin, isosorbide mononitrate, and isosorbide dinitrate, help alleviate chest pain by increasing the oxygen supply to the heart.
• 🌐 Nitrates work by dilating veins, which allows more blood and oxygen to flow into the heart, reducing the preload.
• 💨 Nitroglycerin is used for acute angina and acts quickly when dissolved under the tongue, providing fast relief.
• 🛡 Chronic angina is managed with longer-acting nitrates like isosorbide mononitrate and dinitrate, which require a 12-hour nitrate-free interval to prevent tolerance.
• 🚨 Patients should call emergency services if chest pain persists after the first dose of nitroglycerin, indicating a severe and ongoing issue.
• 💡 Nitrates release nitric oxide, which aids in the formation of cyclic GMP, leading to the relaxation of smooth muscles and vasodilation.
• 🚫 Nitrates are contraindicated with PDE5 inhibitors due to the risk of severe hypotension caused by the combined vasodilatory effects.
• 🤒 Common side effects of nitrates include headache, flushing, dizziness, and orthostatic hypotension, all related to vasodilation.
• 📚 Dosage for acute angina with nitroglycerin is 0.3 to 0.6 milligrams sublingual every 5 minutes, up to three times, while chronic preventative dosing varies for isosorbide mononitrate and dinitrate.

Q & A

What does 'angina pectoris' refer to?

Angina pectoris refers to chest pain caused by an imbalance between the oxygen supply and demand of the heart.

Why does ischemia occur in the heart?

Ischemia occurs when there is not enough oxygen supply to meet the oxygen demand of the heart, potentially causing damage to the heart muscle.

What is the primary function of nitrates in treating angina?

Nitrates primarily function by dilating the veins leading to the heart, increasing the oxygen supply to the heart and thereby relieving chest pain.

How do nitrates increase the oxygen supply to the heart?

Nitrates increase the oxygen supply to the heart by causing vasodilation, which allows more blood and oxygen to flow into the heart.

What is the role of nitric oxide in the action of nitrates?

Nitric oxide, released by nitrates, facilitates the formation of cyclic GMP, which leads to the relaxation of smooth muscles and results in vasodilation.

What are the two types of angina that nitrates can be used for?

Nitrates can be used for acute angina, which requires immediate relief, and chronic angina, which is a preventative measure.

Which brand name is associated with nitroglycerin for acute angina treatment?

Nitrostat is the brand name associated with nitroglycerin, used for treating acute angina.

What is the importance of a 12-hour nitrate-free interval when using isosorbide mononitrate or dinitrate?

A 12-hour nitrate-free interval is necessary to prevent the development of tolerance, ensuring the effectiveness of these long-acting nitrates.

Why are nitrates contraindicated with PDE5 inhibitors?

Nitrates are contraindicated with PDE5 inhibitors because their combined use can lead to severe hypotension due to the increased vasodilation effect caused by the inhibition of cyclic GMP breakdown.

What are some common side effects associated with nitrate use?

Common side effects of nitrate use include headache, flushing, dizziness, and orthostatic hypotension, all of which are related to vasodilation.