Cardiac Glycosides

What are cardiac glycosides?

Cardiac glycosides are medicines that can help people with certain heart conditions. You take them as either a tablet, liquid or capsule. People usually take it once a day at the same time of day.

How cardiac glycosides work

Cardiac glycosides work by inhibiting (holding back) cell membranes from pumping sodium out. This increases the amount of sodium that stays in your cells. This allows more calcium to build up in the cells. When your cells release the calcium, it creates stronger heart muscle contractions. This leads to a higher stroke volume, meaning your heart pumps more blood with each heartbeat. This can increase the total amount of blood your heart pumps, which is called the cardiac output.

Having stronger heart muscle contractions and better cardiac output helps people with heart failure.

These medications also can slow down electrical signals in the atrioventricular (AV) node that controls your heartbeat. This slows down your heart rate, which can also help people with heart failure, especially if they have other heart problems such as atrial fibrillation.

What are examples of cardiac glycosides?

Cardiac glycosides examples include digoxin (Cardoxin® and Lanoxin®), digitalis and digitoxin. They come from the digitalis (foxglove) plant, which is where they get their names. Other cardiac glycoside drugs include oleandrin, bufalin and ouabain. Digoxin is the most commonly prescribed cardiac glycoside.

Who needs to have cardiac glycosides?

People with heart failure or certain arrhythmias may need to take cardiac glycosides if other medicines they tried first didn’t work for them. Cardiac glycosides aren’t first-line (first choice) medicines anymore. Newer and better drugs have replaced cardiac glycosides as first-line medicines.

Medicines your healthcare provider will prescribe first include:

• Beta-blockers.
• ACE inhibitors.
• Diuretics.
• ARBs.

Providers prescribe these first because they’re safer drugs with milder side effects. Providers prescribe cardiac glycosides much less often than they did 30 years ago.

There’s a risk of having too much of a cardiac glycoside in your system. However, these medicines may provide enough benefit to be worth the risk for certain people. An estimated 30% of people across the world who have atrial fibrillation are taking this medicine.

What are cardiac glycosides used for?

Cardiac glycosides are medicines that help your heart muscle have stronger contractions. They also slow down how quickly your heart beats when you have certain heart conditions.

Researchers are exploring the use of cardiac glycosides to keep several types of cancer cells from multiplying. If research proves that this can work, it can have an impact on various kinds of cancer. It could provide new treatments for many people.

What do cardiac glycosides treat?

Cardiac glycosides treat several heart issues:

• Heart failure. Healthcare providers have used digoxin for heart failure for 200 years.
• Atrial fibrillation. Providers have prescribed digoxin for atrial fibrillation for more than 50 years.

Which cardiac glycoside is used in heart failure?

Healthcare providers prescribe digoxin for heart failure, especially if you also have atrial fibrillation. It’s not the first-line treatment of heart failure alone.

What are the advantages of cardiac glycosides?

Cardiac glycosides improve cardiac output in people who have heart failure. They also help slow down heartbeats that are too fast. Symptoms may improve in people taking cardiac glycosides. The medicine may also help people have fewer hospital stays for atrial fibrillation and/or heart failure.

What are the risks or complications of cardiac glycosides?

Some people experience cardiac glycoside side effects that may include:

• Blurry vision.
• Headache.
• Lightheadedness.
• A rash.
• Sleepiness.
• Abnormal heart rhythms.

The amount of cardiac glycosides that can cause side effects isn’t much more than the amount that treats people. This means it can be easy for people to experience side effects while on this medicine, especially if they have low potassium.

Because cardiac glycosides stay in your body for a while, these medications can build up. This is why you’ll most likely take a low dose if you’re taking a cardiac glycoside long term. Also, a provider may check to see how much of the drug is in your system from time to time to make sure you’re on a dose that’s therapeutic but doesn’t cause side effects.

Toxicity from cardiac glycosides can cause:

• Abnormal heart rhythms that can be fatal.
• Sleepiness.
• Vision issues, such as seeing a yellow or green tint.
• Upset stomach.

Fluids, electrolytes and medicines can treat toxicity from cardiac glycosides.

How long do cardiac glycosides take to work?

It can take a few weeks or even a few months for cardiac glycosides to help you feel better.

When should I see my healthcare provider?

Contact your provider right away if you have these side effects while taking cardiac glycosides:

• Trouble breathing.
• Swelling in your feet or hands.
• Upset stomach.
• Diarrhea.
• Lack of a desire to eat.

A note from Cleveland Clinic

If you’re taking cardiac glycosides, it’s important to keep taking your medicine, even if you feel better. Stay in touch with your provider to let them know how the medicine is affecting you. They may want to check your blood to see if you have the right dose in your system. Taking the right dose is important so you can avoid an overdose.