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Digoxin | Nursing considerations, responsibilities, implications

Hassan Magdy
Digoxin is a drug that belongs to the chemical class "Digitalis glycoside", it's used to treat arrhythmias, and it's an Antiarrhythmic cardiotonic medication.

Cardiac glycosides are a group of drugs derived from digitalis, a substance that occurs naturally in foxglove plants. The most commonly used cardiac glycoside is digoxin.
Digoxin Nursing considerations, responsibilities, implications
Digitalis, β-adrenoceptor agonists, and selective phosphodiesterase III inhibitors have been used clinically as cardiotonic agents to improve hemodynamic parameters, primarily heart rate (HR) and blood pressure (BP).
Cardiotonic agents have the potential risk of intracellular Calcium ions overload leading to cardiac arrhythmias and myocardial cell injury that could ultimately lead to myocardial cell death.
(Endoh, 2002).

It's Pregnancy category: C

Indications of digoxin

To treat:
  • heart failure
  • atrial flutter
Atrial flutter occurs due to formation of an abnormal circuit in heart, it causes heart to beat faster, "Supraventricular tachycardia". Treatment is usually catheter ablation, a procedure that scars heart tissues to block abnormal heart circuit.
atrial flutter ECG
ECG of a 47-year-old female with atrial flutter.
  • atrial fibrillation
In which, atria contract randomly rapidly, the heart pacemaker is overridden by abnormal impulses. The heart muscle cannot relax properly leading to low heart's efficiency.
It tends to affect certain groups of people, such as older people and people living with long-term (chronic) conditions such as heart disease, high blood pressure or obesity.
May be triggered by drinking too much alcohol or smoking.
  • Paroxysmal atrial fibrillation: episodic, usually end in 48 hours without treatment.
  • Persistent atrial fibrillation: episodic lasting > 7 days.
  • Permanent atrial fibrillation.
  • long-standing atrial fibrillation: patient complaining of atrial fibrillation for over a year.
Atrial Fibrillation ECG
Atrial Fibrillation in two leads.

(National Health Center, 2021).
  • paroxysmal atrial tachycardia with rapid digitalization

Dosage of digoxin

Dosing forms

  • Capsules
  • I.V injection

Adult dosage of digoxin IV

  • Loading: 10 to 15 mcg/kg in 3 divided doses every 6 to 8 hr, with first dose equal to 50% of total dose. 
  • Maintenance: 125 to 350 mcg daily once or twice daily.

Children dosage of digoxin IV

  1. Children over age 10.
    • Loading: 8 to 12 mcg/kg in 3 or more divided doses, with first dose equal to 50% of total dose.
    • Subsequent doses given every 6 to 8 hr.
    • Maintenance: 2 to 3 mcg/kg once daily.
  2. Children ages 6 to 10.
    • Loading: 15 to 30 mcg/kg in 3 or more divided doses, with first dose equal to 50% of total dose.
    • Subsequent doses given every 6 to 8 hr.
    • Maintenance: 4 to 8 mcg/kg daily in 2 divided doses.
  3. Children ages 2 to 5.
    • Loading: 25 to 35 mcg/kg in 3 or more divided doses, with first dose equal to 50% of total dose.
    • Subsequent doses given every 6 to 8 hr.
    • Maintenance: 6 to 9 mcg/kg daily in 2 divided doses.
  4. Infants ages 1 to 24 months.
    • Loading: 30 to 50 mcg/kg in 3 or more divided doses, with first dose equal to 50% of total dose.
    • Subsequent doses every 6 to 8 hr.
    • Maintenance: 7.5 to 12 mcg/kg daily in 2 divided doses.
  5. Full-term neonates.
    • Loading: 20 to 30 mcg/kg in 3 or more divided doses, with first dose equal to 50% of total dose.
    • Subsequent doses given every 6 to 8 hr.
    • Maintenance: 5 to 8 mcg/kg daily in 2 divided doses.
  6. Premature neonates.
    • Loading: 15 to 25 mcg/kg in 3 or more divided doses, with first dose equal to 50% of total dose.
    • Subsequent doses given every 6 to 8 hr.
    • Maintenance: 4 to 6 mcg/kg daily in 2 divided doses.

Adult dosage of digoxin tablets

    • Loading: 10 to 15 mcg/kg total dose given in 3 divided doses every 6 to 8 hr, with first dose equal to 50% of total dose.
    • Maintenance: 125 to 500 mcg daily.

    Children dosage of digoxin tablets

      1. Children over age 10.
        • Loading: 10 to 15 mcg/kg total given in 3 divided doses every 6 to 8 hr, with first dose equal to 50% of total dose.
        • Maintenance: 2.5 to 5 mcg/kg daily.
      2. Children ages 5 to 10.
        • Loading: 20 to 35 mcg/kg in 3 divided doses every 6 to 8 hr.
        • Maintenance: 5 to 10 mcg/kg daily in 2 divided doses.
      3. Children ages 2 to 5.
        • Loading: 30 to 40 mcg/kg in 3 divided doses every 6 to 8 hr.
        • Maintenance: 7.5 to 10 mcg/kg daily in 2 divided doses.
      4. Infants ages 1 to 24 months.
        • Loading: 35 to 60 mcg/kg in 3 divided doses every 6 to 8 hr.
        • Maintenance: 10 to 15 mcg/kg daily in 2 divided doses.
      5. Full-term neonates.
        • Loading: 25 to 35 mcg/ kg in 3 divided doses every 6 to 8 hr.
        • Maintenance: 6 to 10 mcg/kg daily in 2 divided doses.
      6. Premature neonates.
        • Loading: 20 to 30 mcg/kg in 3 divided doses every 6 to 8 hr.
        • Maintenance: 5 to 7.5 mcg/kg daily in 2 divided doses.

      Dosage adjustment for digoxin for geriatric patients

      Dosage carefully adjusted for patients who are elderly or debilitated or have implanted pacemakers because toxicity may develop at doses tolerated by most patients.
      (Jones & Bartlett Learning, 2015).

      Digoxin mechanism of action

      Increases the force and velocity of myocardial contraction, resulting in positive inotropic effects.
      An inotrope is an agent that alters the force or energy of muscular contractions. Positive inotropic agents strengthen the force of muscular contractions.
      Inhibits sodium-potassium regulating enzyme resulting in increased intracellular levels of sodium and calcium. Promotes intracellular movement of calcium and enhances myocardial contraction.

      Digoxin produces antiarrhythmic effects by decreasing the conduction rate and increasing the effective refractory period of the AV node.
      Refractory period of the AV node is the minimum interval between two ventricular impulses from the atria.
      Acts on CNS to enhance activity of the vagus nerve, slowing contractions through the sinoatrial and atrioventricular nodes and providing an antiarrhythmic effect.

      Pharmacokinetics of digoxin

      1. Absorption: In the intestinal tract, Capsules are absorbed followed by the elixir form, and then tablets.
      2. Distribution: widely throughout the body with highest concentrations in the heart muscle, liver, and kidneys.
      3. Metabolism: a small amount of digoxin is metabolized in the liver and gut by bacteria.
      4. Excretion: Most of the drug is excreted by the kidneys unchanged.
      (Jones & Bartlett Learning, 2015).

      Pharmacodynamics of digoxin

      Digoxin is indicated treat heart failure because it:
      • Increase intracellular calcium at the cell membrane, enabling stronger heart contractions.
      • Enhance the movement of calcium into the myocardial cells
      • Stimulate the release or block the reuptake of norepinephrine at the adrenergic nerve terminal.
      (Jones & Bartlett Learning, 2015).

      Digoxin interactions

      Drug-drug Interactions

      1. Rifampin, barbiturates, cholestyramine, antacids, kaolin and pectin, sulfasalazine, neomycin, and metoclopramide reduce the therapeutic effects of digoxin.
      2. Calcium preparations: quinidine, verapamil, cyclosporine, tetracycline, nefazodone, clarithromycin, propafenone, amiodarone, spironolactone, hydroxychloroquine, erythromycin, itraconazole, and omeprazole increase the risk of digoxin toxicity.
      3. Amphotericin B, potassium-wasting diuretics, and steroids taken with digoxin may cause hypokalemia (low potassium levels) and increase the risk of digoxin toxicity.
      4. Beta-adrenergic blockers and calcium channel blockers taken with digoxin may cause an excessively slow heart rate and arrhythmias.
      5. Neuromuscular-blocking drugs, such as succinylcholine, and thyroid preparations, such as levothyroxine, increase the risk of arrhythmias when taken with digoxin.

      Drug-Natural products interactions

      The herbal preparations St. John’s wort and ginseng can increase levels of digoxin and increase the risk of toxicity.
      (Scott & McGrath, 2011).

      Drug-Food interactions

      • high-fiber food: Inhibited digoxin absorption
      (Jones & Bartlett Learning, 2015).

      Adverse Reactions and side-effects of digoxin

      Central nervous system 

      • Confusion, drowsiness, headache, syncope
      • depression
      • extreme weakness

      Cardiovascular system

      • Arrhythmias
      • heart block

      Eye, ear, nose, and throat

      • Blurred vision
      • colored halos around objects

      Gastrointestinal system

      • Abdominal discomfort or pain, diarrhea
      • anorexia
      • nausea & vomiting
      Digoxin may lead to electrolyte imbalances. (Scott & McGrath, 2011).

      Digoxin toxicity

      Digoxin toxicity happens due to elevated levels of serum digoxin.
      Therapeutic levels of digoxin are 0.8-2.0 ng/mL. The toxic level is >2.4 ng/mL. (Yang et al., 2012).
      Be aware that digoxin has a narrow therapeutic index, meaning that:
      1. A dose producing therapeutic effects may produce signs of toxicity.
      2. Individuals with hypokalemia can develop toxicity even when their digoxin levels aren’t elevated.

      Signs of digoxin toxicity

      • slow to rapid ventricular rhythms
      • abdominal discomfort, nausea and vomiting
      • blurred vision
      • anorexia
      • mental changes.

      Antidote of digoxin

      Digoxin immune Fab (antigen-binding fragment) derived from specific anti-digoxin antibodies. Dosage is determined by the serum digoxin level or the estimated amount of digoxin medication ingested.
      (Scott & McGrath, 2011)

      Contraindications of Digoxin

      • Hypersensitive carotid sinus syndrome.
      • hypersensitivity to digoxin.
      • presence or history of digitalis toxicity or idiosyncratic reaction to digoxin.
      • ventricular fibrillation & ventricular tachycardia unless heart failure occurs unrelated to digoxin therapy.
      (Jones & Bartlett Learning, 2015).

      Nursing Considerations for digoxin

      • Digoxin is not recommended in patients with restrictive cardiomyopathy, constrictive pericarditis, amyloid heart disease, or acute cor pulmonale involving heart failure associated with preserved left ventricular ejection fraction because of increased susceptibility to digoxin toxicity. The drug is also not recommended in patients with idiopathic hypertrophic subaortic stenosis because outflow obstruction may worsen because of the inotropic effects of digoxin.
      • Thiamine deficiency in patients with beri beri heart disease if left untreated, digoxin therapy may be ineffective.
      • If patient has acute or unstable chronic atrial fibrillation, assess for drug effectiveness.
      • Ventricular rate may not normalize even when serum drug level falls within therapeutic range; raising the dosage may not produce a therapeutic effect, however lead to toxicity.
      • Elderly and geriatric patients those with coronary insufficiency, are more susceptible to arrhythmias, if digitalis toxicity occurs.
      • Monitor patient’s serum potassium level regularly because hypokalemia predisposes to digitalis toxicity and serious arrhythmias.
      (Jones & Bartlett Learning, 2015).

      Nursing implications for digoxin

      • Give parenteral digoxin undiluted, or dilute with a four times greater sterile water volume for injection, normal saline solution, or D5W for I.V. administration. Once diluted, give immediately. 
      • Discard if solution is markedly discolored or contains precipitate.
      • Before giving each dose, take patient’s apical pulse and notify physician if it’s below 60 beats/minute.
      • Monitor patient closely for signs of digitalis toxicity, If they appear, notify physician.
      • check serum digoxin level as ordered, and expect to withhold drug until level is known.
      • Monitor ECG continuously.
      • Get ECG regularly as ordered in elderly patients because of their smaller body mass and reduced renal clearance.
      • Monitor potassium level often when giving potassium salts because hyperkalemia in patients receiving digoxin can be fatal.

      Patient health teaching for digoxin

      • Emphasize significance of taking digoxin precisely as prescribed.
      • Caution around possible harmfulness from taking too much and diminished adequacy from taking too little.
      • Instruct patient to take digoxin at same time each day to assist increase adherence.
      • Teach patient how to take her pulse, and instruct her to do so before each dosage. Urge her to inform prescriber on the off chance that beat falls underneath 60 beats/minute or abruptly increases.
      • Inform patient that small, white 0.25-mg tablets can effortlessly be confused with other drugs. Caution against carrying digoxin in anything other than its unique labeled holder.
      • Emphasize need to utilize special dropper provided with solution to guarantee exact dose measurement. 
      • Instruct patient to require a missed dosage as soon as she recollects in case within 12 hours of planned measurements. In case not, encourage her to inform prescriber instantly.
      • Urge patient to inform prescriber in the event that she encounters unfavorable responses, such as GI trouble or beat changes.
      • Instruct patient to carry therapeutic identification that indicates her need for digoxin.
      • Advise patient to consult prescriber before using other drugs, including OTC products

      Nursing Care plan for Digoxin: Assessment

      • Get a patient history of the fundamental condition in prior to therapy.
      • Survey drug effectiveness by measuring apical pulse, before each dose.
      • Evaluate ECG when ordered, and regularly assess the patient’s cardiopulmonary status for signs of improvement.
      • Monitor digoxin levels (therapeutic blood levels range from 0.5 to 2 ng/mL).
      • screen for digoxin serum levels 8 hours after the last dose per oral.
      • Look after potassium levels.
      • Take considerable precautions regarding adverse reactions and drug interactions.

      Nursing care plan for digoxin: nursing diagnoses

      1. Decreased cardiac output related to underlying condition
      2. Risk for injury related to possible adverse reactions and digoxin toxicity
      3. Deficient knowledge related to drug therapy

      Nursing care plan for digoxin: Planning patient's goals

      • Cardiac output will improve as evidenced by vital signs, urine output, and level of consciousness.
      • Risk for digoxin toxicity will be minimized.
      • The patient will demonstrate drug administration procedure and will list symptoms of digoxin toxicity, drug therapy importance, side-effects and precautions.

      Nursing care plan for digoxin: Implementation, implications and nursing responsibilities

      • Decrease patients with compromised renal functions dose.
      • Before giving a loading dose, Establish baseline data (heart rate and rhythm, blood pressure, and electrolyte levels) and question the patient about recent use of cardiac glycosides (within the previous 3 weeks).
      • Divide loading dose over the first 24 hours unless the clinical situation indicates otherwise.
      • Monitor pulse.
      • Before giving the drug, take the patient’s apical pulse for a minute. Record and report to the prescriber significant changes
        1. a sudden increase or decrease in rate
        2. pulse deficit
        3. irregular beat
        4. regularization
        5. If these changes occur, check the patient’s blood pressure and obtain a 12-lead ECG.
      • Withhold the drug and notify the prescriber if the pulse rate slows to 60 beats/minute or less.
      • Infuse the IV form of the drug slowly over at least 5 minutes.
      • Withhold the drug for 1 to 2 days before elective cardioversion. Adjust the dose after cardioversion.
      • Treat arrhythmias with phenytoin IV or lidocaine IV, and treat potentially life-threatening toxicity with specific antigen-binding fragments (such as digoxin immune Fab).
      • Teach the patient about digoxin, including signs and symptoms of digoxin toxicity.

      Nursing care plan for digoxin: Evaluation

      • Patient maintains normal cardiac output.
      • Patient is free from digoxin toxicity symptoms.
      • Patient and his family list drug therapy importance, side-effects and precautions. 
      Download Nursing care plan for digoxin PDF from slide share.

      References:

      1. Endoh, M. (2002). Mechanisms of action of novel cardiotonic agents. Journal of Cardiovascular Pharmacology, 40(3), 323–338. https://doi.org/10.1097/00005344-200209000-00001 
      2. Jones & Bartlett Learning. (2015). 2015 Nurse's drug handbook. Jones & Bartlett Learning. 
      3. National Health Center. (2021, May 17). Atrial fibrillation. https://www.nhs.uk/conditions/atrial-fibrillation/. 
      4. Scott, W. N., & McGrath, D. (2011). Nursing pharmacology made incredibly easy! Wolters Kluwer Health/Lippincott Williams & Wilkins. 
      5. Yang, E. H., Shah, S., & Criley, J. M. (2012). Digitalis toxicity: A fading but crucial complication to recognize. The American Journal of Medicine, 125(4), 337–343. https://doi.org/10.1016/j.amjmed.2011.09.019 

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