Pharmacology, part 9: Cardiovascular Medications - Atropine & Antidysrhythmic Classes III & IV

by Cathy Parkes

In this article, we cover cardiovascular medications - atropine & antidysrhythmic classes III & IV. Atropine is used to treat the symptoms of low heart rate and antidysrhythmic medications are drugs that are used to treat abnormal rhythms of the heart, such as atrial fibrillation, atrial flutter, ventricular tachycardia, and ventricular fibrillation. The Nursing Pharmacology video series follows along with our Pharmacology Flashcards, which are intended to help RN and PN nursing students study for nursing school exams, including the ATI, HESI, and NCLEX.

Class 3 antidysrhythmic medications - potassium channel blockers (amiodarone)

Amiodarone (Nextrone, Pacerone) is a potassium channel blocker used to treat and prevent certain types of serious, life-threatening ventricular arrhythmias. Amiodarone is in a class of medications called antiarrhythmics and works by relaxing overactive heart muscles.

Mode of action

Amiodarone works primarily by blocking potassium rectifier currents that are responsible for the repolarization of the heart during phase 3 of the cardiac action potential.

Side effects

Amiodarone carries many serious side effects, including hypotension, bradycardia, pulmonary toxicity, liver toxicity, thyroid dysfunction, blue/gray skin discoloration and cough.

Black box warning

Amiodarone (Nextrone, Pacerone) carries a black box warning because of the cardiac toxicity, liver toxicity, and pulmonary toxicity it produces in the body.

Cool Chicken Amy owes me one hundred dollars, but she is in the hospital with vfib on an amiodarone drip… so I guess it’s not a good time to collect.

Patient teaching

Patients should be informed that amiodarone is a unique drug that should not be consumed with grapefruit juice. Amiodarone is processed by enzymes in your intestine to its active form. Grapefruit contains compounds that slow down this process and therefore might not be able to control problems associated with your heart rate and rhythm.

Patients on amiodarone should be instructed to report a cough.

Class 4 antidysrhythmic medications - calcium channel blockers (verapamil, diltiazem)

Verapamil (Calan) and diltiazem (Cardizem) are a class of medications called calcium-channel blockers. They work by relaxing the blood vessels so the heart does not have to pump as hard. It also increases the supply of blood and oxygen to the heart. These medications are used to treat atrial fibrillation, atrial flutter, as well as supraventricular tachycardia.

Side effects

Side effects with calcium channel blockers include hypotension, peripheral edema, bradycardia, headache, and constipation.

Nursing care

When a patient is going to be on a calcium channel blocker, their EKGs and vital signs will need to be monitored very closely. They’ll also need to change positions slowly due to the side effect of hypotension.

Class 5 antidysrhythmics - (adenosine, digoxin, magnesium)

Adenosine (Adenocard, Adenoscan), digoxin (Digox), and magnesium (Almora, Maginex) are class 5 antidysrhythmic medications used to treat irregular heartbeats and supraventricular tachycardia. Magnesium is also used as a magnesium supplement, and we cover that later in this Pharmacology series.

Cool Chicken Mom walked into my “den of sin” and ended up with tachycardia. She needed adenosine to slow her rhythm down.

Side effects

Side effects with adenosine include arrhythmias as well as shortness of breath and hypotension.

A VERY important side effect of adenosine is that it can and will stop the heart (on purpose) for 6-12 seconds. This is an expected finding, but important to know!

Nursing care and patient teaching

If your patient is taking this medication, you'll need to monitor their EKG rhythm and also teach them to change positions slowly.

An important note about administering adenosine is it must be pushed fast through a large bore IV because it has a very short half-life. Some nurses like to joke that adenosine is not IV push but an IV "slam"!

Anticholinergic or antimuscarinic medications - atropine

Atropine (Atropen) is a medication used to treat symptoms of low heart rate (bradycardia), heart block, reducing salivation and bronchial secretions before surgery or as an antidote for overdose of cholinergic drugs and mushroom poisoning.

Cool Chicken Atropine is the trampoline to get your heart rate up.

Mode of action

Atropine inhibits acetylcholine sites in the smooth muscles as well as the secretory glands and the central nervous system. It decreases vagal stimulation of the heart, which allows for an increase in the heart rate.

Side effects of atropine

The side effects of atropine are the same side effects as other anticholinergic medications. Patients on atropine can experience blurred vision, dry mouth, urinary retention, constipation, and possibly tachycardia.

Cathy’s favorite way to remember the side effects of anticholinergic medications is “can’t pee, can’t see, can’t spit, and can’t poop”.

Nursing care

When a patient is on atropine, they will need to be monitored for urinary retention as it can cause urinary tract infections, bladder damage, kidney damage and incontinence. The patients fiber and fluid intake should increase in order to prevent constipation. Lithium is also not recommended with taking anticholinergic medications.


Full transcript

Okay! In this video, we are going to be talking about antidysrhythmic medications, class III, IV, and V, as well as an anticholinergic, antimuscarinic medication that is also used for dysrhythmias.

So let's talk about class III antidysrhythmic medications. These are potassium channel blockers, and the key medication to know within this class is amiodarone.

You would use amiodarone for severe dysrhythmias such as ventricular fibrillation and ventricular tachycardia.

So this medication carries many serious side effects, including hypotension, bradycardia, pulmonary toxicity, liver toxicity, and thyroid dysfunction.

It does carry a black box warning because of the cardiac toxicity, the liver toxicity, and the pulmonary toxicity.

So the way I remember this medication, my little hint here that's on my card, is that Amy owes me $100, but she's in the hospital with v-fib on an amiodarone drip, so it's probably not a good time to collect. So again, Amy owes me $100, so amiodarone. And just think about her in the hospital on amiodarone drip, and that's why you can't get your $100 back.

So I'm amused by this. I don't know if you are. I like the cool chicken hint, too, that's one of my favorites, but this one's definitely top five for me.

Other key points about amiodarone is that your patient should not consume grapefruit juice while they're taking this medication.

Also, keep in mind that sotalol, is another medication that is officially within this class, Class 3 antidysrhythmic, but it is a nonselective beta blocker, so I don't know why they stuck it here and not into Class 2, but officially, sotalol is a Class 3 antidysrhythmic. But again, I would really focus your attention on amiodarone.

Now, let's briefly talk about Class 4 antidysrhythmic medications, which are calcium channel blockers.

This class includes medications such as verapamil and diltiazem which, if you recall, we talked about when we covered medications for hypertension and angina. So calcium channel blockers, like I said, are Class 4 antidysrhythmics.

They can treat atrial fibrillation, atrial flutter, as well as supraventricular tachycardia.

So side effects with calcium channel blockers include hypotension, peripheral edema, bradycardia, headache, and constipation.

And if your patient is going to be on a calcium channel blocker, you're going to want to monitor their EKGs and their vital signs, and then teach them to change positions slowly due to the side effect of hypotension.

Okay. So our Class 5 antidysrhythmic is adenosine.

Adenosine is used to treat supraventricular tachycardia.

And the way I remember this one, this is also my top five of hints here, is let's say you have some shady business going on in your bedroom and your mom walks in on your den of sin, right, adenosine, she walks in on your den of sin and it gives her tachycardia because she's seeing something, whatever you got going on in there. And so she ends up needing adenosine to slow her rhythm down. So that's my little hint for adenosine.

Side effects with adenosine include arrhythmias as well as shortness of breath and hypotension.

Other Class 5 antiarrhythmics include digoxin as well as magnesium sulfate.

If your patient is taking this medication, you'll need to monitor their EKG rhythm and then also teach them to change positions slowly.

Okay. Lastly, here with the antidysrhythmics, I want to talk about an anticholinergic or antimuscarinic medication that is used for arrhythmias, and that is atropine.

Atropine is a really important medicine to know.

It is used for sinus bradycardia. It can also be used for heart block, and it can also be used to help decrease secretions during surgery.

So the tip I want to offer here is one that was sent in by a member of our Level Up crew, and they said that atropine is the trampoline to help get your heart rate up. So I love it. That's an amazing hint.

So the mode of action of atropine is that it inhibits acetylcholine sites in the smooth muscles as well as the secretory glands and the central nervous system. So it decreases vagal stimulation of the heart, which allows for an increase in the heart rate.

However, the side effects of atropine are anticholinergic side effects, and you remember my little PG-13 hint for anticholinergic side effects, which is can't pee, can't see, can't spit, and can't poop, right? So we're going to have blurred vision, dry mouth, urinary retention, constipation, and possibly tachycardia as well.

So when your patient is on atropine, you're going to want to monitor for urinary retention, because we definitely don't want that. We're going to want to increase their fiber and fluid intake in order to prevent that constipation as well.

So that is it for our antidysrhythmic medications. I hope this video has been helpful, and I will pick it up with more videos soon. Thanks for watching!


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