Home Drug Guide Digoxin

Drug Guide

Generic Name

Digoxin

Brand Names Lanoxin, Lanoxin Pediatric, Lanoxicaps, Digoxin Pediatric

Classification

Therapeutic: Cardiac glycoside, Antiarrhythmic

Pharmacological: Inhibitor of Na+/K+-ATPase

FDA Approved Indications

Heart failure, atrial fibrillation, atrial flutter

Mechanism of Action

Inhibits sodium-potassium ATPase enzyme, leading to an increase in intracellular calcium in cardiac cells, which enhances cardiac contractility and modifies electrical conduction in the heart.

Dosage and Administration

Adult: Typically 0.125 to 0.25 mg once daily, adjusted based on response and serum levels.

Pediatric: Dosing varies by age and weight; typically 10-15 mcg/kg daily divided into multiple doses.

Geriatric: Start at lower doses due to increased sensitivity and renal impairment, usually 0.125 mg once daily.

Renal Impairment: Lower doses are generally advised; serum levels should be monitored closely.

Hepatic Impairment: No specific dose adjustment recommended, but caution advised.

Pharmacokinetics

Absorption: Well absorbed orally, with 70-80% bioavailability.

Distribution: Widely distributed in body tissues, crosses placenta, enters breast milk.

Metabolism: Minimal hepatic metabolism; primarily excreted unchanged in urine.

Excretion: Renal excretion; dose adjustments needed in renal impairment.

Half Life: Approximately 36-44 hours in adults; shorter in children.

Contraindications

Ventricular fibrillation
Uncorrected severe hypertension

Precautions

Use cautiously in renal impairment, hypokalemia, hypomagnesemia, or hypercalcemia; monitor serum levels regularly.
Pregnancy Category C; use only if clearly needed; consider fetal risks.

Adverse Reactions - Common

Nausea (Common)
Visual disturbances (blurred or yellow vision) (Common)
Fatigue (Common)

Adverse Reactions - Serious

Arrhythmias, including ventricular arrhythmias (Serious)
Heart block (Serious)
Digoxin toxicity which may present with gastrointestinal symptoms, visual disturbances, and heart rhythm changes (Serious)

Drug-Drug Interactions

Diuretics (increase risk of hypokalemia),
Beta-blockers and calcium channel blockers (additive negative chronotropic effects),
Amiodarone (increases digoxin levels)

Drug-Food Interactions

High-fiber foods (can decrease absorption)

Drug-Herb Interactions

N/A

Nursing Implications

Assessment: Monitor apical pulse for 1 minute before administering; assess for signs of toxicity.

Diagnoses:

Risk for electrolyte imbalance related to diuretic use or other factors.

Implementation: Administer after checking pulse, monitor serum digoxin levels, electrolytes, renal function.

Evaluation: Assess for therapeutic response (improved heart failure symptoms, controlled arrhythmias) and toxicity signs.

Patient/Family Teaching

Do not change dose or medication without healthcare provider’s guidance.
Report symptoms of toxicity: nausea, vomiting, visual changes, dizziness, irregular heartbeat.
Maintain consistent dietary intake, especially of fiber and potassium-rich foods.

Special Considerations

Black Box Warnings:

Potentially serious or fatal arrhythmias and toxicity

Genetic Factors: Variations in genes related to drug metabolism may affect serum levels.

Lab Test Interference: Can interfere with assays for serum iodine, biotin, and other lab tests.

Overdose Management

Signs/Symptoms: Nausea, vomiting, dizziness, visual disturbances, arrhythmias, bradycardia.

Treatment: Discontinue digoxin, administer activated charcoal if recent ingestion, correct electrolyte imbalances, and use digoxin-specific antibody fragments (Digibind) in severe toxicity.

Storage and Handling

Storage: Store at room temperature, away from moisture and light.

Stability: Stable until the expiration date printed on the packaging.