Digoxin

Also Known As:
Serum Digoxin Level

Formal Name:
Digoxin
serum

This article was last modified on May 8, 2020

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Therapeutic Drug Monitoring

At a Glance

Why Get Tested?

To determine if the concentration of digoxin in your blood is at a therapeutic level or to detect toxic levels of the drug in your blood

When To Get Tested?

After the start of digoxin therapy and at regular intervals to ensure that drug levels are within therapeutic range (not too low or too high as to be toxic)

Sample Required?

A blood sample drawn by a needle from a vein

Test Preparation Needed?

No special preparation is needed, but timing of sample collection is important, and you may be instructed to have your blood drawn a specific number of hours after your last dose of digoxin, typically 6-8 hours. When having your blood drawn, tell the person collecting your blood sample when you took your last dose of digoxin.

What is being tested?

Digoxin is a drug used to treat heart failure and abnormal heart rhythms. Heart failure, including congestive heart failure (CHF), causes the heart to become less effective at circulating blood. As a result, blood backs up into the legs, hands, feet, lungs and liver, causing swelling, shortness of breath, and fatigue. This test measures the amount of digoxin in the blood.

Digoxin is prescribed to relieve some symptoms of heart failure. It strengthens the contractions of the heart and helps it to pump blood more efficiently. Digoxin also helps control the heart rate and abnormal heart rhythms known as arrhythmias. It will not cure heart failure or arrhythmias, which are long-term (chronic) conditions, but can help to manage the symptoms along with diet, exercise, and other medications.

Digoxin levels must be monitored because the drug has a narrow safety range. If the level in the blood is too low, symptoms may recur. If the level is too high, toxicity may occur. Digoxin dosage may be adjusted based on levels measured.

Common Questions

How is the test used?

A digoxin test is used to monitor the drug level in the blood. The dose of digoxin prescribed may be adjusted depending on the level measured. Your health care practitioner may order one or more digoxin tests when you begin treatment to determine if the initial dosage is within therapeutic range and then order it at regular intervals to ensure that the therapeutic level is maintained. A digoxin test may also be used to determine if symptoms are due to an insufficient amount of the drug or to digoxin toxicity.

When is it ordered?

A health care practitioner will order the test to measure digoxin at the beginning of drug therapy to ensure correct dosage. Digoxin takes approximately one to two weeks to reach a steady level in the blood and in the target organ, the heart. A test done at that time will reflect more accurately whether you are receiving the right amount of digoxin.

Once the dose is determined, routine monitoring of digoxin levels, at a frequency determined by your healthcare practitioner, will verify correct dosage.

A digoxin test may be ordered when it is suspected that levels are too low if you are taking the medication and have symptoms of heart failure, such as:

Fatigue
Shortness of breath
Swelling in the hands and feet (edema)

The test may be ordered when toxicity is suspected and you have signs and symptoms such as:

Dizziness
Blurred vision or seeing yellow or green halos
Vomiting
Diarrhea
Irregular heartbeat
Difficulty breathing
Loss of appetite

Changes in health status can affect levels of digoxin and its ability to control symptoms. Digoxin tests may be done, and the dose adjusted if necessary, when you have conditions that may affect blood levels and effectiveness of digoxin, such as kidney or thyroid problems, cancer, or stomach or intestinal illness.

What does the test result mean?

For congestive heart failure, the therapeutic range may be between 0.5 and 0.8 nanograms/milliliter (ng/mL). Each person’s response to medications is different. Many factors, including kidney function and use of other medications, may be involved. If your symptoms do not improve or if you experience side effects, then your healthcare provider may need to adjust the digoxin dose up or down according to your needs.

Is there anything else I should know?

When prescribed digoxin, you should discuss with your health care provider and pharmacist all other prescription and over-the-counter medications, dietary supplements, and herbal remedies you are taking. These can affect the level of digoxin in the blood and its effectiveness. Be sure to notify your healthcare provider about any changes in use of these products while you are taking digoxin.

Prescription drugs that can interact with digoxin include: quinidine, flecainide, verapamil, amiodarone, amiodarone, azole antifungals (such as itraconazole, ketoconazole), cyclosporine, lapatinib, macrolide antibiotics (such as clarithromycin, erythromycin), propafenone, ranolazine, rifampin, eliglustat and ciprofloxacin. Herbal remedies such as St. John’s wort, oleander, and lily of the valley may affect levels of digoxin in the blood. Eating licorice may also affect blood levels of the drug.

Digoxin is primarily cleared from the body by the kidneys. If you have kidney problems, your healthcare provider may want to monitor kidney function and blood potassium levels since kidney dysfunction and low levels of potassium can result in symptoms of digoxin toxicity.

Digoxin toxicity can be aggravated by potassium and magnesium levels, so a healthcare provider may monitor electrolytes and magnesium levels.

People with a certain type of irregular heartbeat called atrial fibrillation are advised not to take digoxin as it may increase their risk of dying.

In cases where toxic levels of digoxin are found, a healthcare practitioner may administer a specialized antidote (digoxin immune FAB) to reverse the effects of the digoxin.

How long will I need to be on digoxin?

Digoxin is prescribed to treat heart failure, a long-term, chronic condition. It will not cure heart failure but will help to control it. You may have to take digoxin — and have tests to monitor its level in the blood — for the rest of your life.

Who orders digoxin tests?

Your primary care provider may order the test, but a cardiologist may also monitor levels of digoxin in your blood.

Why is it important to have my blood drawn for my digoxin test at a certain time?

Timing of the digoxin blood test is important because if the sample is drawn too soon after a dose, the results of the test may be erroneously high and will show a toxic level when that is not the case. Typically, a blood sample should be drawn 6-8 hours after a dose. Many times, the blood sample will be drawn just before the next dose is to be taken.

View Sources

Sources Used in Current Review

2020 review performed by Morgan E. Pacini, MS, Technical/General Supervisor, LSA Toxicology Laboratory.

(July 3, 2019) Chan, B. Clinical outcomes from early use of digoxin-specific antibodies versus observation in chronic digoxin poisoning (ATOM-4). Clinical Toxicology. Available online at https://www.tandfonline.com/doi/full/10.1080/15563650.2018.1546010?scroll=top&needAccess=true. Accessed on 4/12/2020.

(January 7, 2020) Thibault, N. Effect of eliglustat on the pharmacokinetics of digoxin, metoprolol, and oral contraceptives and absorption of eliglustat when coadministered with acid-reducing agents. Molecular Genetics and Metabolism. Available online at https://www.sciencedirect.com/science/article/pii/S1096719219305463. Accessed on 4/14/2020.

(May 8, 2019) Bennett, S. Use of digoxin in heart failure. Journal of Prescribing Practice. Available online at https://www.magonlinelibrary.com/doi/abs/10.12968/jprp.2019.1.5.224. Accessed on 4/11/2020.

University of Illinois-Chicago, Drug Information Group. (2018). Digoxin, Oral Tablet. Healthline. Available online at https://www.healthline.com/health/digoxin-oral-tablet. Accessed on 4/10/2020.

(March 19, 2017) AFib Patients Taking Digoxin Have Increased Risk of Death. ACC News Story. Available online at https://www.acc.org/latest-in-cardiology/articles/2017/03/13/17/58/sun-1045-am-aristotle-digoxin-and-mortality-in-afib-patients-with-and-without-hf-acc-2017. Accessed on 4/14/2020.

Sources Used in Previous Reviews

A Manual of Laboratory & Diagnostic Tests. 6th ed. Fischbach F, ed. Philadelphia: Lippincott Williams & Wilkins; 2000.

Clinical Chemistry: Principles, Procedures, and Correlations. Bishop M, Duben-Engelkirk J, Fody E, eds. 4th ed. Philadelphia: Lippincott Williams & Wilkins; 2000.

Sacher RA, McPherson RA, Campos J. Widmann’s Clinical Interpretation of Laboratory Tests. 11th ed. Philadelphia: F.A. Davis Company; 2000.

Goodman & Gilman’s The Pharmacological Basis Of Therapeutics. 11th Edition. Lazo J, Goodman L S, Parker K L, eds, McGraw-Hill, September 2005.

National Heart, Lung, and Blood Institute (September 2003). Heart and Vascular Diseases: Heart Failure: Summary page (On line information). Available onlin at http://www.nhlbi.nih.gov/health/dci/Diseases/Hf/HF_All.html.

Terra, S G, Washam J B, Dunham, G D, and Gattis W A, (Oct 1999). Therapeutic Range of Digoxin’s Efficacy in Heart Failure: What Is the Evidence? Pharmacotherapy, 19(10): 1123-1126, (On line journal). Available online at http://www.medscape.com/viewarticle/418044.

Gibbs C R, Davies M K Davies, Lip G Y H, (Feb 2000). Management: Digoxin and other inotropes, Beta-blockers, and antiarrhythmic and antithrombotic treatment, BMJ. 320(7233): 495-498. PDF available for download at http://www.pubmedcentral.gov/articlerender.fcgi?tool=pmcentrez&artid=1127534.

Mihai Gheorghiade, MD; Kirkwood F. Adams, Jr, MD; Wilson S. Colucci, MD (2004). Digoxin in the Management of Cardiovascular Disorders, Circulation; 109:2959-2964 (On line journal). Available online through http://circ.ahajournals.org.

Rich, M. (2003 September). Drug Therapy of Heart Failure in the Elderly. Am J Geriatr Cardiol 12(4):235-242 (On line journal). Available online at http://www.medscape.com/viewarticle/460844.

Yusuf, S (November 1997). Digoxin in heart failure: results of the recent digoxin investigation group trial in the context of other treatments for heart failure Eur Heart J, 18: 1685-1688. PDF available for download through http://eurheartj.oxfordjournals.org.

The Digitalis Investigation Group, (February 1997). The Effect Of Digoxin on Mortality and Morbidity in Patients with Heart Failure, NEJM volume 336:525-533 (On line journal). Available online at http://content.nejm.org/cgi/content/full/336/8/525.

Catherine A. Hammett-Stabler, PhD, DABCC, FACB. Pathology and Laboratory Medicine, UNC-Chapel Hill.

(Revised 2010 January). What is Heart Failure? National Heart Lung and Blood Institute [On-line information]. Available online at http://www.nhlbi.nih.gov/health/dci/Diseases/Hf/HF_WhatIs.html. Accessed February 2010.

A.D.A.M. Editorial Team (Updated 2009 February 3). Cardiac glycoside overdose. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/002581.htm. Accessed February 2010.

Dugdale, D. (Updated 2009 January 23). Digitalis toxicity. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000165.htm. Accessed February 2010.

Ahmed, A. (2008 May 21). An Update on the Role of Digoxin in Older Adults with Chronic Heart Failure. Medscape Today from Geriatrics & Aging 2008;11(1):37-41 [On-line information]. Available online at http://www.medscape.com/viewarticle/573855. Accessed February 2010.

Patel, V. and James, P. (Updated 2010 January 6). Digitalis Toxicity. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/154336-overview. Accessed February 2010.

Digitalis toxicity. Medline Plus Medical Encyclopedia. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000165.htm. Last updated January 13, 2013. Accessed July 26, 2013.

Digoxin Drug Level. Health Encyclopedia. University of Rochester Medical Center. Available online at http://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=digoxin_drug_level. Accessed July 26, 2013.

Moffett BS, Valdes SO, Kim JJ. Possible digoxin toxicity associated with concomitant ciprofloxacin therapy. Int J Clin Pharm. 2013 Abstract available online at http://www.ncbi.nlm.nih.gov/pubmed/23868369. Published online July 19, 2013. Accessed July 27, 2013.

Raja Rao MP, Panduranga P, Sulaiman K, and Al-Jufail. Digoxin Toxicity with Normal Digoxin and Serum Potassium Levels: Beware of Magnesium, the Hidden Malefactor. J Emerg Med. Abstract available online at http://www.ncbi.nlm.nih.gov/pubmed/23685098. Published May 16, 2013. Accessed July 27, 2013.

For Consumers: Avoiding Drug Interactions. U.S. Food and Drug Administration. Available online at http://www.fda.gov/ForConsumers/ConsumerUpdates/UCM096386. Last updated November 28, 2008. Accessed July 26, 2013.

Digoxin Oral Interactions. WebMD. Available online at http://www.webmd.com/drugs/drug-4358-Digoxin+Oral.aspx?drugid=4358&drugname=Digoxin+Oral. Last updated March 2013. Accessed July 31, 2013.

2016 review by Nicholas Heger, PhD, CC (NRCC), Assistant Director – Clinical Chemistry, Tufts Medical Center Boston.

Yancy CW, Jessup M, Bozkurt B, et al. American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation. 2013;128(16):e240-e327.

Bilbault P1, Oubaassine R, Rahmani H, Lavaux T, Castelain V, Sauder P, Schneider F. Emergency step-by-step specific immunotherapy in severe digoxin poisoning: an observational cohort study. Eur J Emerg Med. 2009 Jun;16(3):145-9.

Brent, Jeffrey; Wallace, Kevin; Burkhart, Keith; Phillips, Scott and Donovan, J. Ward. (© 2005). Critical Care Toxicology – Diagnosis and Management of the Critically Poisoned Patient, 1st edition. Mosby, Inc., Philadelphia, PA. Pp. 1325-1333.

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