Cardiac glycosides are a small group of natural compounds that help the heart pump more strongly. They come from the foxglove plant (digitalis) and have been used for centuries to treat a weak heart. Today, doctors mainly prescribe digoxin, a synthetic version, for heart failure and certain rhythm problems.
When you take a cardiac glycoside, it increases the force of each heartbeat and slows down the heart rate. This double effect can improve blood flow and reduce symptoms like shortness of breath, swelling, and fatigue. The drug works by inhibiting an enzyme called Na+/K+‑ATPase, which changes calcium levels inside heart cells and makes the muscle contract better.
Most of the time, digoxin is given to people with chronic heart failure who still have symptoms despite other medicines. It can also be used for atrial fibrillation—a fast, irregular rhythm—because it helps control the rate. Your doctor will consider factors such as kidney function, age, and other meds before starting a glycoside, since the drug can build up in the body.
Typical dosing starts low, often 0.125 mg once daily, and is adjusted based on blood levels. A therapeutic range is usually 0.5–2.0 ng/mL; staying below 2.0 reduces the risk of toxicity. Your doctor may order blood tests after a week, then monthly for the first few months.
Because cardiac glycosides have a narrow safety window, it’s crucial to follow the prescription exactly. Missed doses should be taken as soon as you remember, unless it’s almost time for the next dose—don’t double up.
Side effects can include nausea, vomiting, visual changes (like seeing yellow‑green halos), and feeling unusually weak or confused. These signs often mean the drug level is too high. If you notice any of them, call your healthcare provider right away.
Kidney problems or dehydration make toxicity more likely, so stay well‑hydrated and keep your doctor informed about any new illnesses. Certain drugs—such as some antibiotics, anti‑arrhythmics, and diuretics—can interact with digoxin, so always share your full medication list.
In rare cases, severe toxicity can cause dangerous heart rhythm changes. Emergency treatment may involve activated charcoal, anti‑digoxin antibodies, or electrolyte correction. Knowing the symptoms and acting quickly can save lives.
Overall, cardiac glycosides are a valuable tool when used correctly. They can improve quality of life for many with heart failure or atrial fibrillation, but they require careful monitoring. Talk to your doctor about whether a glycoside is right for you, and never stop or change the dose without professional guidance.
A thorough comparison of Lanoxin (Digoxin) with six common cardiac alternatives, covering how they work, benefits, risks, and how to choose the right option for heart failure or atrial fibrillation.