11.06 ACE (angiotensin-converting enzyme) Inhibitors

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Okay, so we gonna talk about ACE inhibitor also known as a angiotensin converting enzyme inhibitors. In this module, we gonna cover this drugs but before we cover these drugs, we highly recommend you watch our video, RAA system on Renin Angiotensin Aldosterone System, because if you understand that one, you’ll understand these drugs better.

So, let’s talk about the indication first. These medications are used for high blood pressure, so, if someone has a high blood pressure, these medications are used to control the high blood pressure. Also, these medications are also used for the control of Diabetes symptoms related to the kidneys. So, symptoms related to kidneys. And it also used in the heart failure as well. Now, in the next slide, we’ll go over the mechanism of action and we’ll see why do we use these medications for these disease processes, okay?

So, this image is basically showing the RAA system and if you have looked at the video about the RAA system, you know, the angiotensin converting enzyme right here converts the Angiotensin I into Angiotensin II. And the Angiotensin II has a wide variety of effect in our body including increase in the sympathetic system, it increases the vasoconstriction, and increases the blood pressure. It also increases the sodium reabsorption, and also the water, while it increases the potassium excretion and so forth. So, when we block this ACE enzyme, nothing’s gonna convert from here. The Angiotensin I is not gonna be able to convert to Angiotensin II. So, we are breaking this chain from right here and that means, there’s no sympathetic activity, no sodium and water reabsorption is gonna happen and no vasoconstriction.

So, let’s see what’s gonna happen now when we block the ACE enzyme. Let’s go to the next slide and take a look. So, this is a kind of a simplified version of the RAA system. So, when we block this enzyme right here, decreased in sodium reabsorption, decrease in water reabsorption, now, this is gonna decrease in blood volume and fluid overload. And that is the reason why we use these drugs for heart failure. Now, at the same time, when the sodium reabsorption and the water reabsorption gonna decrease, it’s gonna increase the potassium reabsorption, and potassium level is gonna increase. Okay, so remember this one from the previous slide. In the normal RAA system, potassium level goes down but when we block this angiotensin converting enzyme, the potassium reabsorption is gonna go up and the potassium level is gonna go up. This will help you to remember one of the side effect that we will go over in the next slide. Now, when we block this enzyme, the angiotensin won’t be used and it’s not gonna work on sympathetic nervous system as well and it’s not gonna cause the vasoconstriction. So, what it’s gonna do? It’s gonna decrease the vasoconstriction. When it decreases the vasoconstriction, the blood pressure is gonna decrease, when the blood pressure is decreased, heart will be able to pump blood more easily. So, heart able to pump blood more easily because it won’t have that resistance to pump, the heart won’t have that resistance to come over when the blood pressure high because it’s not gonna do vasoconstriction anymore. And that is the reason, it’s also we use this medication to decrease the blood pressure and also for the heart failure. ‘Cause it’s gonna decrease the heart workload. Alright, so, that’s how, the basically, the mechanism of action of the ACE inhibitors.

Let’s look at into the next slide, the side effects, contraindication and the nursing consideration to remember. The very first one is severe hyppotension after the first dose. So, there are many patient can have severe hypotension after the first dose and hypotension symptoms would be, you have to look for as a nurse is dizziness, lightheadedness, and faintness upon rising. So, you have to instruct the patient after the first dose to not get up suddenly because it can decrease the blood pressure significantly and they can feel dizzy and they can fall. As a nurse, you want to assess the blood pressure before giving the first dose and then after periodically to make sure their blood pressure is not falling down significantly. Okay, now, as we talked into the previous slide, let’s go back to the previous slide really quickly. That it increases the potassium reabsorption when you block the Angiotensin converting enzyme, it’s gonna increase the potassium reabsorption, it’s gonna increase the potassium level. And that is the reason one of the side effects of this medication is high potassium level. So, what are the symptoms of the high potassium? Could have been confusion, numbness or tingling in hands and feet, can cause a cardiac arrhythmia. And also, since it can cause the high potasssium level, it is contraindicated into the potassium sparing diuretic and also the salt substitute. Potassium sparing diuretic much increases the potassium reabsorption as well, so you don’t really want to put patient on 2 different medication which both increases the potassium reabsorption and increases the potassium level. So, they are contraindicated in a patient who’s taking potassium sparing diuretic. And also, the salt substitute because in the salt substitute, they add potassium. So, that’s gonna, if they are on salt substitute, it’s gonna even increase more potassium in the body. So, that’s why they are contraindicated.

One of the main side effects that as a nurse you have to remember and for the NCLEX as well, is a dry cough. Remember like the ACE enzymes is located in the lungs. Now, this medication inhibits the ACE enzyme in the lungs can increase the level of bradykinins in the lungs, which is basically an inflammatory agent. And because of that accumulates this bradykinin in the lungs, it can cause a dry persistent cough. So, in that case, what do you do is either tell the patient to take a cough medication per doctor’s instructions or they usually change medication if it’s really intolerable and really persistent dry cough, they change medication to the ARBs which is Angiotensin II receptor blocker, which we gonna cover in different presentation. Angiotensin II Receptor Blockers. This medication can also change the ability to taste, so, the patient can have salty or metallic taste and also sometimes decreases the ability to taste. And in that case, you really want to tell the doctor and change the medication to something else to control either the blood pressure or the heart failure, okay? Now, another important side effects to remember is Angioedema which is swelling around the lips, eyes, throat and other body regions. Now, since this can cause swelling around the throat, it can lead to airway closure. So, this is kinda serious side effects of this medication, is the Angioedema. So, you really want to educate the patient about this Angioedema and kind of lock after the first dose or in a few weeks. So, you really wanna tell the patient to monitor the swelling of these lips, eyes, throat, and if it happens, tell the doctor as soon as possible, emergently, I would say. Now, there’s a particular drug in this class, it’s called Captopril. It can cause a neutropenia which is basically decrease in white blood cells. So, you want to monitor the white blood cells before you give the medication periodically to make sure the patient is not gonna have Neutropenia. And since this medication decreases the blood flow to the renal, I mean, kidneys, you really wanna monitor the BUN and creatinine which represents kidney function.

Now, in which patient these medications are contraindicated? Now, if we go back to the side effects, and the mechanism of action, it’s kinda self-explanatory like in which patients this is contraindicated. First, it definitely decreases the blood flow to the kidneys. So, it is contraindication in a patient who has a decreased renal function. Most of the medication is metabolized by the liver, so, if the liver, if a patient has a liver damage, you don’t wanna really give this medication because it can accumulate in the body to toxic level. Now, Captopril can cause neutropenia. So, if a patient has either one of these: bone marrow depression, immunosuppressant medication or if they have any kind of autoimmune disease, we don’t really wanna give patient this medication because it can even cause more decrease in immune system. And if they have decreased in immune system, they can have, the indication would be like a sore throat and all other infections. So, you wanna educate the patient about that too.

Now, how do you find these ACE inhibitors? There’s a really easy way. You can call these drugs -pril drugs. If you look at the names of this medication, where end of all drugs it ends with prils. So, any drugs that ends with prils, it’s ACE inhibitors. Quite easy.

Alright, so, if you have any questions about this medication, or any mechanism of action or side effects, you can e-mail us or contact us. Thanks for watching.
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