Digitalis is a medicine that is used to treat certain heart conditions. Digitalis toxicity can be a side effect of digitalis therapy. It may occur when you take too much of the drug at one time. It can also occur when levels of the drug build up for other reasons such as other medical problems you have.
The most common prescription form of this medicine is called digoxin. Digitoxin is another form of digitalis.
Digitalis toxicity can be caused by high levels of digitalis in the body. A lower tolerance to the drug can also cause digitalis toxicity. People with lower tolerance may have a normal level of digitalis in their blood. They may develop digitalis toxicity if they have other risk factors.
People with heart failure who take digoxin are commonly given medicines called diuretics. This drugs remove excess fluid from the body. Many diuretics can cause potassium loss. A low level of potassium in the body can increase the risk of digitalis toxicity. Digitalis toxicity may also develop in people who take digoxin and have a low level of magnesium in their body.
You are more likely to have this condition if you take digoxin, digitoxin, or other digitalis medicines along with drugs that interact with it. Some of these drugs are quinidine, flecainide, verapamil, and amiodarone.
If your kidneys do not work well, digitalis can build up in your body. Normally, it is removed through the urine. Any problem that affects how your kidneys work (including dehydration) makes digitalis toxicity more likely.
Some plants contain chemicals that can cause symptoms similar to digitalis toxicity if they are eaten. These include foxglove, oleander, and lily of the valley.
Your health care provider will examine you.
Your heart rate may be rapid, or slow and irregular.
An ECG is done to check for irregular heartbeats.
Blood tests that will be done include:
- Blood chemistry
- Kidney function tests, including BUN and creatinine
- Digitoxin and digoxin test to check levels
- Potassium level
- Magnesium level
If the person has stopped breathing, call 911 or the local emergency number, then start CPR.
If the person is having trouble breathing, call 911 or the local emergency number.
At the hospital, symptoms will be treated as appropriate.
Digitoxin blood level may be lowered with repeated doses of charcoal, given after gastric lavage.
Methods to cause vomiting are usually not done because vomiting can worsen slow heart rhythms.
In severe cases, medicines called digoxin-specific antibodies may be prescribed. Dialysis may be needed to reduce the level of digitalis in the body.
How well a person does depends on the severity of the toxicity and if it has caused an irregular heart rhythm.
Call your provider if you are taking a digitalis medicine and you have symptoms of toxicity.
If you take digitalis medicine, you should have your blood level checked regularly. Blood tests should also be done to check for conditions that make this toxicity more common.
Potassium supplements may be prescribed if you take diuretics and digitalis together. A potassium-sparing diuretic may also be prescribed.
Cole JB. Cardiovascular drugs. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 147.
Goldberger AL, Goldberger ZD, Shvilkin A. Digitalis toxicity. In: Goldberger AL, Goldberger ZD, Shvilkin A, eds. Goldberger's Clinical Electrocardiography. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 20.
Nelson LS, Ford MD. Acute poisoning. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 102.
Waller DG, Sampson AP. Heart failure. In: Waller DG, Sampson AP, eds. Medical Pharmacology and Therapeutics. 5th ed. Philadelphia, PA: Elsevier; 2018:chap 7.
Updated by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
Open Resources for Nursing (Open RN)
Digoxin
Digoxin is a cardiac glycoside medication that has been used for centuries to treat heart failure. It has three effects on heart muscle: positive inotropic action (increases contractility, stroke volume and, thus, cardiac output), negative chronotropic action (decreases heart rate), and negative dromotropic action (decrease conduction of cardiac cells).[1]
Mechanism of Action
Digoxin works by inhibiting the sodium and potassium pump, which results in an increase in intracellular sodium and an influx of calcium into cardiac cells, causing the cardiac muscle fibers to contract more efficiently and increase cardiac output.[2]
Indications for Use
This medication is used as second-line treatment for patients who have heart failure or atrial fibrillation. Due to the risk for digoxin toxicity, the clinical use of digoxin has decreased and alternative, safer medications are being used.
Nursing Considerations Across the Lifespan
Apical pulse should be taken for a full minute before administration of this medication. If the apical pulse is less than 60, the dose should be withheld and the prescribing provider notified.
Serum digoxin levels should be monitored, with a normal therapeutic range from 0.8 to 2 ng/mL.
Serum potassium levels should also be closely monitored for patients on digoxin because hypokalemia increases the effect of digoxin and can result in digoxin toxicity. Normal potassium level is 3.5 to 5.0 mEq/L, and a result less than 3.5 should be immediately reported to the provider.
Nurses should closely monitor signs of digoxin toxicity. Geriatric patients have an increased risk for developing digoxin toxicity. Digibind is used to treat digoxin toxicity.
Adverse/Side Effects
Overdose or accumulation of digoxin causes digoxin toxicity. Signs and symptoms of digoxin toxicity are bradycardia (heart rate less than 60), nausea, vomiting, visual changes (halos), and arrhythmias. Cardiotoxicity is a serious adverse effect with ventricular dysrhythmias. Toxicity of this medication typically occurs at greater than 2 ng/mL, but some patients may have signs and symptoms at lower levels. Pediatric patients typically present with bradycardia or arrhythmias if toxicity is occuring.
Decreased renal function, hypokalemia, hypercalcemia, and hypomagnesemia may increase risk for digoxin toxicity.
Common side effects include GI symptoms, headache, weakness, dizziness, anxiety, depression, delirium, and hallucination.[3]
Patient Teaching & Education
The patient should be instructed to follow the prescribed dosing regimen and take medications at the same time each day. The patient should be cautious not to double up on medication doses. Additionally, the patient should consult the healthcare provider if two or more doses of medication are missed for follow-up instruction.
Patients should receive education regarding pulse rate monitoring and report any pulse rate less than 60. If the patient experiences signs of digoxin toxicity, this should be reported to the provider immediately. The medication should be stored in its original container and care should be taken not to mix the medication with other medications.[4]
Now let’s take a closer look at the medication grid for digoxin in Table 6.7a.[5]
Table 6.7a Digoxin Medication Grid
| Administration Considerations | Therapeutic EffectsAdverse/Side Effects|||
| digoxin | Assess apical heart rate Assess serum digoxin and potassium levels Assess for signs and symptoms of digoxin toxicity | Increased cardiac output | Digoxin toxicity; early signs include nausea, vomiting, and diarrhea Bradycardia and arrhythmias Headache, weakness, dizziness, and mental changes such as anxiety or hallucinations Gynecomastia (with prolonged use) |
- Why should a nurse assess the apical pulse for 1 full minute before administering digoxin?
- How does a nurse evaluate if digoxin is effective?
- Why must the nurse monitor serum potassium levels as well as digoxin levels?
- A nurse enters a patient’s room and the patient complains “My vision seems strange and I feel nauseated.” What is the nurse’s next best action?
Note: Answers to the Critical Thinking activities can be found in the “Answer Key” sections at the end of the book.
Digibind
Digibind is used to treat digoxin toxicity.
Mechanism of Action
Digibind binds to digoxin molecules, reducing free digoxin.
Indications for Use
This medication is the antidote for digoxin. Digibind will be administered when a patient is experiencing life-threatening digoxin toxicity.
Nursing Considerations Across the Lifespan
There are no contraindications when using digibind.
Adverse/Side Effects
The most common effects a patient may experience are to have worsening heart failure, worsening atrial fibrillation, and hypokalemia. [6]
Patient Teaching & Education
The patient should report any signs of worsening heart failure, atrial fibrillation, or hypokalemia immediately to the healthcare provider.[7]
Now let’s take a closer look at the medication grid for digibind in Table 5.6b.[8]
Table 5.6b Medication Grid for Digibind.
| digoxin immune fab (Digibind) | Give when patients are experiencing life- threatening digoxin toxicity | Reduce free digoxin | Worsening heart failure Worsening atrial fibrillation Hypokalemia |