Digoxin

What it is and how it works

Mechanism of Action All of digoxin’s actions are mediated through its effects on NaK–ATPase. This enzyme, the “sodium pump,” is responsible for maintaining the intracellular milieu throughout the body by moving sodium ions out of and potassium ions into cells. By inhibiting NaK–ATPase, digoxin • causes increased availability of intracellular calcium in the myocardium and conduction system, with consequent increased inotropy, increased automaticity, and reduced conduction velocity; • indirectly causes parasympathetic stimulation of the autonomic nervous system, with consequent effects on the sino-atrial (SA) and atrioventricular (AV) nodes.

Indications

Digoxin is a cardiac glycoside indicated in adults for the treatment of mild to moderate heart failure and for the control of resting ventricular rate in patients with chronic atrial fibrillation. ( 1.1 , 1.3 ) In pediatric patients with heart failure, digoxin is indicated to increase myocardial contractility. Heart Failure in Adults Digoxin Oral Solution is indicated for the treatment of mild to moderate heart failure. Digoxin increases left ventricular ejection fraction and improves heart failure symptoms as evidenced by increased exercise capacity and decreased heart failure-related hospitalizations and emergency care, while having no effect on mortality. Where possible, digoxin should be used with a diuretic and an angiotensin-converting enzyme inhibitor, but an optimal order for starting these three drugs cannot be specified. Heart Failure in Pediatric Patients Digoxin is indicated to increase myocardial contractility in pediatric patients with heart failure.

Dosage and administration (summary)

Toxic levels of digoxin are only slightly higher than therapeutic levels. The pharmacokinetics of digoxin are complex and dose determination should take into account patient-specific factors (age, lean body weight, renal function, etc.). ( 2.4 , 2.5 ) Patients should be monitored for toxicity and therapeutic effect and doses should be adjusted, accordingly. General Dosing Considerations The dose of digoxin should be based on clinical assessment but individual patient factors should be taken into consideration.

Contraindications

Allergy to digoxin is rare. Digoxin is contraindicated in patients with a known hypersensitivity to digoxin or other forms of digitalis. Digitalis glycosides, such as digoxin, are contraindicated in ventricular fibrillation. • Known hypersensitivity to digoxin or other forms of digitalis. • Ventricular fibrillation.

Warnings and precautions

• Accessory AV Pathway: Increased risk of rapid ventricular response leading to ventricular fibrillation. • Sinus Node Disease and AV Block: Digoxin use can exacerbate the condition and may cause advanced or complete heart block. • Misidentification of Digoxin Toxicity: Signs and symptoms of digoxin toxicity may be mistaken for worsening symptoms of congestive heart failure. • Preserved Left Ventricular Systolic Function: Patients with heart failure with preserved left ventricular ejection fraction may be more susceptible to digoxin toxicity.

Pregnancy

Pregnancy Risk Summary Experience with digoxin in pregnant women over several decades, based on published retrospective clinical studies and case reports, has not led to the identification of a drug associated risk of major birth defects, miscarriage or adverse maternal and fetal outcomes.

Storage and supply

Digoxin Oral Solution, USP 50 mcg per 1 mL is supplied as a (lime-flavored) clear, colorless solution. NDC 0054-0057-46: Bottle of 60 mL with a calibrated oral syringe Storage Store at 20° to 25°C (68° to 77°F). Protect from light.

Source: Digoxin (Digoxin) — US FDA prescribing information, 2025-04-10, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.