Nitroglycerin is a medication that widens blood vessels, a process known as vasodilation. This action helps to improve blood flow throughout the body by relaxing the muscular walls of these vessels. By facilitating broader pathways for blood, nitroglycerin can reduce the effort the heart needs to pump.
How Nitroglycerin Works
Nitroglycerin is converted into nitric oxide within the body’s cells. Once formed, nitric oxide acts as a signaling molecule that relaxes smooth muscle cells in blood vessel walls. This relaxation allows the blood vessels to expand, increasing their diameter and enhancing blood flow. The widening of these vessels subsequently reduces the resistance against which the heart must pump blood.
This vasodilation decreases the heart’s workload, as it requires less force to circulate blood through less constricted pathways. For chest pain, or angina, nitroglycerin’s primary benefit stems from its ability to dilate veins, a process called venodilation. This action reduces the amount of blood returning to the heart, known as preload, which diminishes the volume of blood the heart must pump with each beat. This reduction in cardiac demand helps alleviate the discomfort associated with angina.
Conditions Treated
Nitroglycerin is primarily used to manage and prevent episodes of angina, which is chest pain caused by reduced blood flow to the heart muscle. By widening the coronary arteries, it helps to increase the supply of oxygen-rich blood to the heart, thereby easing the pain. It can be taken preemptively before activities known to trigger angina or during an acute attack to provide rapid relief.
Beyond its application in heart conditions, nitroglycerin also serves a specific purpose in treating anal fissures. When applied topically, it helps to relax the smooth muscles around the anus, which can reduce pressure and improve blood flow to the affected area. This increased blood supply promotes healing and alleviates pain associated with the fissure.
Ways to Take Nitroglycerin
Nitroglycerin is available in several forms, each designed for different situations and speeds of action. For rapid relief of angina, sublingual tablets are placed under the tongue for quick absorption into the bloodstream. An oral spray can also be administered onto or under the tongue for a fast effect.
For sustained prevention of angina, extended-release tablets are taken orally, releasing medication slowly. Topical ointments are applied to the skin, providing a continuous, longer-lasting effect. Transdermal patches also deliver nitroglycerin through the skin over an extended period to maintain consistent medication levels. In severe or emergency situations, nitroglycerin can be given intravenously in a hospital setting for precise and immediate control.
What to Know Before Using Nitroglycerin
Using nitroglycerin can lead to several common side effects, largely due to its blood pressure-lowering effects. Headaches are a frequent occurrence, often described as throbbing, and result from the dilation of blood vessels in the head. Dizziness and weakness can also occur as a consequence of reduced blood pressure, potentially increasing the risk of falls, especially when standing up quickly.
There are specific situations where nitroglycerin should not be used due to health risks. Individuals with severe anemia should avoid it because the medication can further reduce oxygen delivery to tissues. It is also contraindicated in cases of increased intracranial pressure, such as from a head injury or brain hemorrhage, as vasodilation in the brain could worsen the condition. A serious interaction exists with phosphodiesterase-5 (PDE-5) inhibitors, used for erectile dysfunction, as combining these medications can lead to a severe drop in blood pressure.