Digoxin vs. digitalis: What’s the difference?
- Digoxin and digitalis are cardiac glycosides that are derived from the same plant, the foxglove, used to treat adults with mild to moderate congestive heart failure and to treat abnormally rapid atrial rhythms (atrial fibrillation, atrial flutter, atrial tachycardia).
- Digoxin also is used for increasing myocardial contractility in pediatric patients with heart failure.
- Brand names for digoxin include Lanoxin and Lanoxin Pediatric.
- A brand name for digitalis is Crystodigin.
- Side effects of digoxin and digitalis that are similar include diarrhea and headache.
- Side effects of digoxin that are different from digitalis include nausea, vomiting, dizziness, skin rash, and mental changes.
- Side effects of digitalis that are different from digoxin include loss of appetite, drowsiness, muscle weakness, and fatigue.
What are digoxin and digitalis?
Digoxin is a cardiac glycoside used for treating adults with mild to moderate congestive heart failure and for treating abnormally rapid atrial rhythms (atrial fibrillation, atrial flutter, atrial tachycardia). It also is used for increasing myocardial contractility in pediatric patients with heart failure. Digoxin increases the force of contraction of the muscle of the heart by inhibiting the activity of an enzyme (ATPase) that controls movement of calcium, sodium, and potassium into the heart muscle. Calcium controls the force of contraction. Inhibiting ATPase increases calcium in the heart muscle and therefore increases the force of heart contractions. Digoxin also slows electrical conduction between the atria and the ventricles of the heart and is useful in treating abnormally rapid atrial rhythms.
Digitalis is a cardiac glycoside used to treat certain heart conditions such as congestive heart failure (CHF) and heart rhythm problems (atrial arrhythmias). Digitalis works directly on the heart muscle to strengthen and regulate the heartbeat.
What are the side effects of digoxin and digitalis?
Common side effects include:
Many digoxin side effects are dose dependent and happen when blood levels are over the narrow therapeutic range. Therefore, digoxin side effects can be avoided by keeping blood levels within the therapeutic level. Serious side effects associated with digoxin include:
- heart block,
- rapid heartbeat, and
- slow heart rate.
Digoxin has also been associated with visual disturbance (blurred or yellow vision), abdominal pain, and breast enlargement. Patients with low blood potassium levels can develop digoxin toxicity even when digoxin levels are not considered elevated. Similarly, high calcium and low magnesium blood levels can increase digoxin toxicity and produce serious disturbances in heart rhythm.
As your body adjusts to the medication, the following side effects may occur:
Inform your doctor if you develop any of these side effects:
- visual disturbances (blurred vision or yellow/green halos around objects),
- fast/slow/irregular heartbeat,
- skin rash,
- breast enlargement,
- severe stomach upset.
If you notice any other side effects, contact your doctor or pharmacist.
What is the dosage for digoxin vs. digitalis?
- Digoxin may be taken with or without food.
- Digoxin primarily is eliminated by the kidneys; therefore, the dose of digoxin should be reduced in patients with kidney dysfunction.
- Digoxin blood levels are used for adjusting doses in order to avoid toxicity.
- The usual starting dose is 0.0625-0.25 mg daily depending on age and kidney function.
- The dose may be increased every two weeks to achieve the desired response.
- The usual maintenance dose is 0.125 to 0.5 mg per day.
- Take this medication exactly as directed by your doctor.
- Try to take it at the same time each day.
- To avoid stomach upset, this medication may be taken with food or milk.
- Consult with your doctor before you stop taking this medication.
What drugs interact with digoxin and digitalis?
- Drugs such as gentamicin, tetracycline, ranolazine (Ranexa), verapamil (Calan, Verelan, Verelan PM, Isoptin, Isoptin SR, Covera-HS), quinidine (Quinaglute, Quinide), amiodarone (Cordarone), indomethacin (Indocin, Indocin-SR), alprazolam (Xanax, Xanax XR, Niravam), spironolactone (Aldactone), and itraconazole (Sporanox) can increase digoxin levels and the risk of toxicity. The co-administration of digoxin and beta-blockers (for example propranolol [Inderal, Inderal LA]) or calcium channel blockers or CCBs (for example, verapamil), which also reduce heart rate, can cause serious heart rate slowing.
- Diuretic-induced (for example, by furosemide [Lasix]) reduction in blood potassium or magnesium levels may predispose patients to digoxin-induced abnormal heart rhythms.
- Saquinavir (Invirase) and ritonavir (Norvir) increase the amount of digoxin in the body and may cause digoxin toxicity.
- Mirabegron (Mybetriq) increases digoxin blood levels. The lowest dose of digoxin should be used if by people who are also using mirabegron.
- Omeprazole (Prilosec) and other drugs that reduce stomach acidity may increase blood levels of digoxin.
- thyroid medication,
- erythromycin-like drugs,
- drugs used for cancer,
- dextrothyroxine, and
- St John's wort.
After taking digitalis, wait at least 2 hours before taking the following:
These medications should be taken as far apart from digitalis as possible:
- aminosalicylic acid (PAS),
- Milk of Magnesia, and
Are digoxin and digitalis safe to use while pregnant or breastfeeding?
- There are no adequate studies in pregnant women.
- Digoxin is secreted in breast milk at concentrations similar to concentrations in the mother's blood. However, the total amount of digoxin that will be absorbed from breast milk by the infant may not be enough to cause effects. Nursing mothers should exercise caution when taking digoxin.
- Pregnant women should only use this medication if clearly needed and discuss the risks and benefits with their doctors.
- Digitalis is excreted into breast milk. Women using this medication should consult their doctors before breastfeeding.