27.03 Nitro Compounds

We gonna talk about nitro compounds. The nitro compounds have several drugs in them such as nitroglycerin, sodium nitroprusside. We’ll talk about the examples later. But these drugs are really important as a nurse if you are working in the intensive care because you’ll be giving these drugs to patients very often. So, you need to know what are the side effects, how it works and what to look for if your patient is on the nitro medication.

So, let’s talk about the mechanism of action first. So, there are our vessels, let’s talk about the vein or arteries and they have this vascular endothelial cell in the veins or arteries, basically, the vessels. They produce the nitric oxide substance, and that nitric oxide substance is responsible for the vasodilation. When it does the vasodilation of arteries and veins, so, let’s talk about in each, like what happens when it does the vasodilation of veins. So, when it does the vasodilation of veins, vein can hold more blood, so the amount of blood that’s gonna get back to the heart, it’s gonna decrease when the amount of the blood that’s gonna get back to the heart, it decreased, it’s not, the heart does have to hold increased amount of blood that’s gonna decrease the pressure on the heart wall. It’s just a general mechanism. If you have more blood in your heart, it’s gonna put more pressure on the heart wall, it’s gonna stretch more. If you have less blood in your heart, it’s gonna put less pressure on the heart walls and it’s gonna stretch them less. So, that’s basically the amount of stretch that heart wall has is called the preload. It’s gonna decrease the preload by decreasing the amount of blood getting back to the heart. Now, it’s gonna decrease the afterload as well by causing the vasodilation of artery. So, when ventricles eject the blood out of the heart, it has to overcome the pressure of the arteries. Now, if arteries are constricted, that means, that’s too much pressure. Heart has to pump really hard in order to come over that artery pressure. Now, if it is dilated, there’s not much pressure in the arteries. So, heart do not have to work too hard in order to pump the blood out of the heart. So, that causes the decrease in afterload. That basically reduces the workload of the heart. Now, there’s a third action this nitric oxide has on our heart is it prevents the coronary spasms. It causes the coronary dilation. So, these three mechanisms are important in order to understand this nitro substance.

Let’s talk about the next slide. In which disease condition we use. So, first of all, the hypertension. As we talked in the previous slide, it dilates the arteries, that means it decreases the high blood pressure, basically. So, that’s why it is used in the hypertension as well. Now, when there is a heart failure, that means the heart is not working right. It’s a pump failure, basically. It’s not pumping blood adequately into the body, into the systemic circulation. So, we need to decrease the workload of the heart, which absolutely this drug does. So, we can use these drugs for the heart failure as well. And when there’s a coronary vasal spasms, coronary spasms, angina or myocardial infarction, we can use these drugs to dilate those coronary vessels. So, we can provide blood to cardiac tissue. So, the use of these nitro compounds is they use are basically, main three, the hypertension, heart failure, and angina and myocardial infarction.

So, what drugs are in this class? The first one is sodium nitroprusside. Sodium nitroprusside is mostly work on arteries. So, it’s highly used for hypertension only. When someone comes with a hypertensive emergency, like when their blood pressure is 250/140, then they usually put them on the nitroprusside drips. There’s a Isosorbide dinitrate, Isosorbide mononitrate and you have probably seen this drug a lot, nitroglycerin, if someone has a myocardial infarction, angina pectoris or even a high blood pressure, they would put them on the nitroglycerin. So, these are the four main medication in this class.

The next one is side effects and contraindications. So, one of the main side effects of these drugs is orthostatic hypotension because it dilates the arteries and veins that causes the really really profound hypotension. So, that’s the one you have to be really careful when you’re giving these drugs to your patient. And when you’re giving these drugs to patient, teach them do not get up suddenly because when you get up suddenly, it causes the big drop in the blood pressure and then they can feel dizzy and then they can fall. So, tell them, like from lying position, rise slowly to the sitting position and wait for a couple of minutes right there. If they don’t feel dizzy, then, stand up. And stand up there for a couple of minutes and if they don’t dizzy, then and then, do other activities, otherwise, they can have really really big drop in the blood pressure, and then they can feel dizzy and fall. The other ones are headache, flushing of the face, because all the arteries and veins are dilated and holding all the blood in them causing the redness of face and flushing as well. And it can cause a reflex tachycardia as well because there’s not enough blood getting back to the heart, so heart is thinking, “Okay, I need to supply more blood.” So, it will start beating fast. So, it causes the reflex tachycardia as well. Now, one of the main question and contraindication in NCLEX they often asked is nitro compound and sildenafil which is of use as viagra. So, you do not want to put patient on nitro and this drug at the same time because it can cause really really big drop in the blood pressure. It can impair the coronary artery perfusion and can even, can worsen the angina or it can cause an M.I. (Myocardial Infarction). So, this nitro compound and this slidenafil are contraindicated. You do not want this patient this both drugs. So, be really really careful and the ask ths question very often as well in NCLEX. So, remember that one. And orthostatic hypotension as well.

Alright, that was it about the nitro compounds. If you have any questions, you can let us know. Thank you for watching.