Digoxin Nursing Implications
Digoxin Nursing Pharmacology
Cardiac glycosides are a type of organic compound that elevates the output force of the heart and reduces contraction rate through the inhibition of intracellular sodium-potassium ATPase pump channels. Digoxin is a common drug that belongs to the group of cardiac glycosides.
Digoxin acts on the heart muscle through a mechanism that consequently targets the sino-atrial (SA) and atrioventricular (AV) nodes as a side effect to the body by the parasympathetic stimulation of the autonomic nervous system.
Due to this mechanism, digoxin helps in reducing cardiac strain, thereby assisting in the maintenance of normal heartbeats.
Indications of Digoxin
Digoxin is mainly used for the following medical conditions:
- Heart failure
- Abnormal heart rhythms (arrhythmias such as chronic atrial fibrillation)
Forms and strength of digoxin differs depending on age group, drug indication and creatinine clearance levels. Enlisted below are the various forms and strengths of digoxin.
- As oral solution = 0.05 mg/ml dosage
- As tablet form = 0.0625 mg, 0.125 mg, 0.1875 mg and 0.25 mg dosages
- As injectable solution = 0.1 mg/ml and 0.25 mg/ml dosages
The following are special dosage considerations in administering digoxin:
- When administered for rapid management of atrial fibrillation (in both oral and intravenous forms), initial doses should only be 50% of the recommended total loading dose. Incremental increases with ¼ of the loading dose given on a 6-8 hour gap for two succeeding doses should be considered. It is also warranted that careful assessment is done after each dose given to evaluate patient response and possible toxicity.
- When digoxin is administered as an oral maintenance dose for atrial fibrillation, incremental doses of digoxin are only done every 2 weeks and will depend on patient response, serum drug levels and possible toxicity.
- When digoxin is administered as an injectable maintenance dose for atrial fibrillation, intravenous (IV) doses are preferred over intramuscular (IM) administration due to the risk of developing severe injection site reaction.
- For patients with heart failure, starting the patient on a loading dose of digoxin is not required. However, adjustments are needed and use of lower end dosing is followed for patients with impaired kidney function or low lean body mass.
- Adult dosing modifications of digoxin should always be guided by assessing for the patients estimated creatinine clearance levels and serum drug levels. In addition, a higher dose has no added benefit for patients with heart failure and may even cause increased toxicity. Finally, calculating for the patient’s lean body weight is ideal when giving to geriatric patients.
For Pediatric Patients
- For pediatric patients with heart failure, dosages of digoxin should be started and based on the lower end of the recommended dose to avoid unnecessary toxicity.
- When reducing doses, a 20-25% reduction should be followed when changing among oral, IM or IV therapy forms to avoid sudden clinical changes that may contribute to patient deterioration and possible toxicity.
Mechanism of Action of Digoxin
Digoxin acts on the body through the following mechanisms:
- It inhibits Na-K ATPase, which causes increased availability of intracellular calcium in the heart muscle and the conduction system. Inotropy and automaticity are then consequently raised while conduction rate is diminished. Due to these, the drug indirectly causes parasympathetic stimulation of the autonomic nervous system, subsequently affecting the sino-atrial (SA) and atrioventricular nodes (AV) of the heart.
- It reduces the uptake of catecholamine (hormones responsible for the “fight or flight” mechanism) at the nerve channels, thereby allowing the body’s blood vessels to have increased sensitivity to endogenous or exogenous catecholamine. Because of these, it elevates the sensitivity of baroreceptors, consequently increasing the nerve activity in the carotid sinus, and augmenting sympathetic reaction withdrawal for every elevation in mean arterial pressure.
- On higher concentrations, digoxin intensifies sympathetic outflow from the central nervous system (CNS) towards both cardiac and peripheral sympathetic nerves. Furthermore, it permits progressive outflowing of intracellular potassium thereby elevating the serum potassium levels in the body.
Pharmacokinetics of Digoxin
Pharmacokinetics is a body of pharmaceutical knowledge focused on how an organism affects and changes a drug. As with all medications, digoxin is processed in the body when administered to achieve the goals of medical therapy. Explained below are the mechanisms of pharmacokinetics of digoxin (i.e., absorption, distribution, metabolism and elimination).
- The bioavailability of digoxin is 60 to 80% when in tablet form and 70 to 85% for elixir forms
- The onset of digoxin effects starts within 0.5 to 2 hours initially for oral forms with a 2-6 hour maximal effect. In the IV form, the initial effect starts within 5 to 30 minutes of administration with a maximum effect of up to 1.5 to 4 hours.
- The duration of effectiveness of digoxin lasts for 3 to 4 days.
- The peak serum time of digoxin in oral form is within a 1-3 hour range.
- Digoxin is distributed by attaching 20 to 25% of the time to polypeptides (i.e., protein bound) to be delivered to the various receptors for use by the body.
- The volume distribution (vd), or the volume wherein the drug is distributed to deliver the same concentration in plasma is around 6 to 7 L/kg.
- Digoxin is primarily broken down in the liver to produce metabolites such as digoxigenin bisdigitoxoside and digoxigenin monodigitoxoside (active form).
- Half-life: The body takes 1 to 3 days to eliminate half of the available digoxin in the body.
- Digoxin is removed in the body through the urine (occurs 57 to 80%) and through the feces (occurs 9 to 13%, including bile)
Side Effects of Digoxin
Common side effects of digoxin include the following clinical manifestations:
Adverse Reactions of Digoxin
Patients who are using digoxin may have these serious adverse effects such as:
- mental or mood changes
- vision changes such as blurred vision, green or yellowing of vision, etc.
- enlarged/tender breasts in men
- other types of irregular heartbeats (e.g., unusually fast/slow/irregular)
- allergic drug reaction presenting with: rash, itching/swelling of the face, tongue or throat, severe dizziness, respiratory issues
- heart blocks (e.g., first, second or third degree blocks)
- tachycardia, or rapid heart beat
Drug Interactions of Digoxin
Drug interactions of digoxin from other substances or medications are mentioned below:
- Azole antifungals, class III anti-arrhythmic, dual tyrosine kinase inhibitor, macrolide antibiotics, class 1C anti-arrhythmic, anti-mycobacterial, St. John’s wort among others can affect the elimination of digoxin in the body.
- Cough and cold preparations, diet aids, and non-steroidal anti-inflammatory drugs among others can affect and worsen a patient’s heart failure while on digoxin.
- Digoxin is one of the substances coming from P-glycoprotein during intestinal absorption, renal tubule and biliary-intestinal excretion. Because of this, medications that prompt or impede P-glycoprotein can potentially alter digoxin in the body.
- Certain anti-arrhythmics, when given with digoxin, may increase the incidence rate of Torsades de Pointes.
- Some parathyroid hormone analogs may increase a patient’s susceptibility to elevated serum calcium levels.
- Thyroid supplements that are used for hypothyroidism in patients already taking digoxin may need incremental dosage adjustments as it affects serum levels.
- Some sympathomimetics can raise the cardiac arrhythmia risk of digoxin taking patients.
- Some neuromuscular blocking agents may cause the sudden expulsion of intramuscular potassium, thereby causing arrhythmias to patients on digoxin therapy.
- Intravenous calcium supplements rapidly given can produce fatal arrhythmias to patients on digoxin therapy.
- Some beta-adrenergic blockers, calcium channel blockers and hyperpolarization-activated cyclic nucleotide (HCN) channel blockers can have compounding effects to the AV node conduction that can cause bradycardia and advanced or complete heart blocks.
Cautions for the Use of Digoxin
Caution is highly encouraged when administering digoxin for patients with the following conditions due to its rapid and significant cardiac effects:
- Severe heart failure, including acute cor pulmonale, amyloid heart disease and constrictive pericarditis – Patients with these conditions are susceptible to digoxin toxicity.
- Severe pulmonary disease or hypoxia
- Sick sinus syndrome
- Various electrocardiogram (ECG) rhythms such as severe bradycardia, ventricular tachycardia, ventricular premature contractions, Wolff-Parkinson White syndrome, etc.
- Sinus node disease and AV block – It increases the risk for the development of advanced or complete heart blocks.
- Electrolyte imbalance
- Hypothyroidism or hyperthyroidism
- Renal disease
- When used together with diuretics
Digoxin is not recommended for patients with acute myocardial infarction (AMI) or myocarditis. When utilized for AMI patients, caution is needed for it may increase the oxygen demand of the heart.
Contraindications Against Digoxin
Digoxin is contraindicated in patients with known digoxin hypersensitivity and ventricular fibrillation.
Digoxin overdose and toxicity can happen in both adult and pediatric patients. The clinical manifestations may present similarly with the adverse reactions but may be more recurrent and worse. Clinical manifestations of digoxin toxicity may occur and be frequent for serum levels above 2 ng/ml. In managing digoxin overdose and toxicity, careful consideration of the patient’s clinical picture, current electrolyte levels and thyroid function are essential factors.
Signs and Symptoms of Digoxin Toxicity
- The most common are nausea, vomiting, anorexia and fatigue with an occurrence rate of 30-70% of overdosed patients.
- Hyperkalemia is usually present, especially for patients with impaired renal function.
- A variety of cardiac arrhythmias and dysrhythmias (e.g., Mobitz type 1 A-V block, accelerated junctional rhythm, etc.) is present, with effects occurring 3-6 hours after ingestion that may persist for 24 hours or longer.
- Gastrointestinal symptoms (e.g., nausea, vomiting, etc.) are common with up to 80% incidence rate.
- Neurologic manifestations such as fatigue and CNS discrepancies are also common. Visual disturbances such as changes in color vision (predominance of yellow green) are also prominent in digoxin toxicity.
- Children / Pediatric Patients
- Frequent non-cardiac effects, like in adults, are also observed in children; however, nausea and vomiting are not.
- Weight loss in older children, failure to thrive in infants, abdominal pain, drowsiness and behavioral issues are common in pediatric overdose.
- Cardiac arrhythmias and dysrhythmias common in adults may also occur in children; however, any arrhythmia in children should be considered digoxin toxicity unless ruled out.
Treatment for Digoxin Toxicity / Digitalis Toxicity
- Acute Digoxin Toxicity
The treatment modality for acute digoxin toxicity includes the following:
- Expect the administration of activated charcoal, either via the mouth or through a nasogastric tube.
- Anticipate in placing the patient under cardiac monitoring.
- Discontinue digoxin until the adverse reactions are managed and controlled.
- Expect to correct electrolyte abnormalities such as hypokalemia and hypomagnesemia.
- In the presence of dangerous arrhythmias such as ventricular tachycardia, or hyperkalemia, administer a digoxin antidote as prescribed. For patients with renal impairment, the use of glucose with insulin may be initially utilized to address life-threatening hyperkalemia.
- Anticholinergic agents may be used for parasympathetically activated bradycardia and heart blocks.
- Chronic Digoxin Toxicity
The treatment modality for chronic digoxin toxicity includes the following:
- In cases of overdose, discontinue digoxin and place the patient on cardiac monitoring.
- Anticipate for the correction of any electrolyte abnormalities, thyroid dysfunction or discontinuing of concurrent medications. Ensure monitoring of the patient’s ECG, looking for evidence of potassium toxicity (i.e., peaking of T-waves, etc.)
- Refrain the use of potassium salts for patients exhibiting bradycardia or heart blocks.
- Expect the administration of digoxin antidote if the patient has symptomatic arrhythmias.
Nursing Considerations for Digoxin
The nurse who has digoxin as part of their patient’s therapeutic regimen should be aware of the following considerations:
- General Nursing Considerations
- Focused attention should be exercised when administering digoxin due to the narrow margin between effective therapeutic and toxic doses.
- Digoxin becomes less effective in the presence of hypokalemia or hypocalcemia due to its action towards intracellular and serum potassium levels. It should be avoided when the patient has hypercalcemia or hypomagnesemia due to the risk of dangerous arrhythmias.
- During exercise stress testing, digoxin users may cause false positive ST segment and T wave changes.
- Serum levels of digoxin drawn within 6 to 8 hours from dose will yield false high results due to prolonged distribution phase of the drug.
- Geriatric patients using digoxin have increased risk of developing estrogen-like effects.
- Patients on digoxin who develop atrial arrhythmias with associated hypermetabolic (hyperthyroidism) or hyperdynamic (hypoxia) states are difficult to manage. Treating the underlying cause is the standard before starting digoxin therapy.
- Patients with Beri-beri associated heart disease will not benefit efficiently with digoxin therapy if the underlying B1 (thiamine) insufficiency is not treated.
- Serum concentration levels should be monitored closely when digoxin is used to regulate the heart rate of patients with atrial fibrillation due to increased mortality risks of therapy and narrow therapeutic versus toxic margins.
- Administering Digoxin (IV Compatibilities)
- Digoxin is compatible on the following IV solutions: D5 0.45% Sodium Chloride solution with incorporated 20 meqs of potassium chloride, D5W, lactated ringer’s solution, 0.45% Sodium Chloride solution and 0.9% Sodium Chloride solution
- Digoxin is compatible as additive to IV solutions together with some drugs such as: calcium channel blockers, H2-receptor antagonist, diuretics and sodium channel blockers.
- Digoxin is compatible, together in a syringe, with some inotropic agents, phosphodiesterase enzyme inhibitors and anticoagulants.
- Digoxin is compatible, when administered via the Y-site of IV lines, with some vitamins, electrolytes, oxazilodones, h2-receptor antagonists, fluoroquinolones among others.
- Administering Digoxin (IV Incompatibilities)
- Digoxin is incompatible as additive to IV solutions together with some inotropics.
- Digoxin is incompatible, together in a syringe, with some respiratory stimulants.
- Digoxin is incompatible, when administered via the Y-site of IV lines, with some antifungals, class III anti-arrhythmics, and non-barbiturate sedative among others.
- Administering Digoxin (IV Preparation and Administration)
- Digoxin should be diluted 4 times or more in volume of selected appropriate diluent (e.g., 0.9 % sodium chloride solution, etc.)
- The nurse should slowly inject diluted digoxin over 5 minutes and longer when given pure and undiluted.
- Avoid administration in the presence of precipitate in the vial or ampule.
Digoxin is a severe skin irritant when given via the IV or IM route and may cause skin sloughing as a severe localized skin reaction.
Nursing Diagnosis Digoxin
Possible Digoxin Nursing Diagnosis
Diarrhea related to the side effect of digoxin
Nausea related to side effect of digoxin
Risk for Poisoning related to possible toxicity and/or overdose of digoxin
Risk for Disturbed Sensory Perception related to possible adverse effect of digoxin
Deficient Knowledge related to digoxin
|Digoxin Nursing Interventions||Rationale|
|Assess the patient for signs and symptoms of mild to moderate heart failure and/or chronic atrial fibrillation.||To confirm the indication for administering digoxin.|
|Assess if the patient has a history of an acute myocardial infarction (AMI), myocarditis, ventricular fibrillation (VF), hypokalemia, or Wolf-Parkinson-White syndrome.||Digoxin is generally contraindicated in patients with acute myocardial infarction (AMI) or Wolf-Parkinson-White syndrome because the drug does not help in improving the performance of the left ventricle, and may in fact cause ventricular fibrillation (VF). Studies also showed that digoxin increases the mortality risk of AMI survivors. Hypokalemia is found to be the most common trigger or cause of digoxin toxicity.|
|Check the patient’s allergy status.||Previous allergic reactions to digoxin may render the patient unable to take them. Alternatives to digoxin should therefore be considered in case of allergy.|
|Assess if the patient is pregnant or lactating.||Digoxin should be prescribed in caution to a pregnant woman as it can rapidly cross the placenta.|
|Perform a focused physical assessment on the patient’s heart through and auscultation of heart sounds.||To confirm the indication for administering digoxin.|
|Assess the patient’s mucous membranes and his/her ability to swallow.||To check for any potential problems with administration, hydration, and absorption.|
To ensure that the right form of digoxin is given.
|Collect bloods for potassium levels.||Hypokalemia or low serum potassium levels is the most common cause of digoxin toxicity due to possible dosing errors especially in younger patients. On the other hand, hyperkalemia or high serum potassium level can reduce the effectiveness of digoxin.|
Nursing Planning and Intervention
|Digoxin Nursing Interventions||Rationale|
|Assess the patient’s vital signs, particularly the heart rate / pulse rate prior to administering digoxin.||Digoxin is ideally taken only if the patient’s heart rate or pulse rate is above 60 beats per minute.|
|Administer digoxin with or without food, ideally at the same time each day.||To ensure optimal absorption and therapeutic action by digoxin, as well as reduce possible side effects.|
|Educate the patient about the action, indication, common side effects, and adverse reactions to note when taking digoxin. Instruct the patient on how to self-administer digoxin.||To inform the patient on the basics of digoxin, as well as to empower him/her to safely self-administer the medication.|
|Monitor the patient’s bowel movement and commence a stool chart.||Digoxin may cause diarrhea. Early detection of either side effect can help institute a bowel program and relieve them effectively.|
|Discourage intake of banana, and other potassium-rich foods, potassium supplements, and insoluble dietary fiber with digoxin. If the patient has to eat insoluble fiber, advise to take the digoxin 1 hour before or 2 hours after eating.||Foods high in potassium can cause hyperkalemia, which can reduce the effectiveness of digoxin. Insoluble dietary fiber such as bran can lower the rate of absorption of digoxin in the GI tract.|
|Discourage alcohol consumption while on digoxin.||Alcohol with digoxin can result in abnormal cardiac function and high blood pressure or hypertension. Also, alcohol can make the patient drowsier while on digoxin.|
|Assist the patient with activities of daily living as needed.||Digoxin may cause weakness, drowsiness, and/or disturbed sensory perception. Thus, helping the patient with ADLs as he/she requires is important for his/her safety.|
|The patient may usually break or crush digoxin, unless informed otherwise by the pharmacist.||The effectiveness of digoxin is not usually affected by breaking or crushing the tablets for patients with dysphagia or difficulty of swallowing.|
|Digoxin Nursing Interventions||Rationale|
|Ask the patient to repeat the information about digoxin.||To evaluate the effectiveness of health teaching on digoxin.|
|Monitor the patient’s bloods: potassium levels and digoxin levels.||To ensure that the digoxin did not cause any electrolyte imbalance, particularly high or low potassium levels. Digoxin test is done to monitor the levels of the drug in the blood and ensure that digoxin toxicity is avoided.|
|Monitor the patient’s response to digoxin in terms of side effects, especially heart rate, blood pressure and GI status.||To check for any arrythmias, hypertension, nausea, vomiting, diarrhea, or other GI side effects.|
Ackley, B. J., Ladwig, G. B., Makic, M. B., Martinez-Kratz, M. R., & Zanotti, M. (2020). Nursing diagnoses handbook: An evidence-based guide to planning care. St. Louis, MO: Elsevier. Buy on Amazon
Gulanick, M., & Myers, J. L. (2022). Nursing care plans: Diagnoses, interventions, & outcomes. St. Louis, MO: Elsevier. Buy on Amazon
Ignatavicius, D. D., Workman, M. L., Rebar, C. R., & Heimgartner, N. M. (2018). Medical-surgical nursing: Concepts for interprofessional collaborative care. St. Louis, MO: Elsevier. Buy on Amazon
Silvestri, L. A. (2020). Saunders comprehensive review for the NCLEX-RN examination. St. Louis, MO: Elsevier. Buy on Amazon
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