Lanoxin (digoxin) is a time-tested cardiac glycoside derived from Digitalis lanata, prescribed for the management of atrial fibrillation and congestive heart failure. It functions by increasing myocardial contractility and slowing atrioventricular nodal conduction, offering a targeted approach to stabilizing cardiac function. With decades of clinical validation, it remains a cornerstone in cardiology for patients requiring precise inotropic and chronotropic control. Proper therapeutic drug monitoring is essential to maximize efficacy and minimize toxicity risks.

Features

• Contains digoxin as the active pharmaceutical ingredient
• Available in 125 mcg and 250 mcg scored tablets for accurate dosing
• Long-established pharmacokinetic profile with predictable absorption
• Narrow therapeutic index requiring serum concentration monitoring
• Demonstrated efficacy in controlling ventricular response in atrial fibrillation

Benefits

• Enhances cardiac output by improving myocardial contraction strength in systolic heart failure
• Provides controlled ventricular rate reduction in patients with atrial fibrillation
• Reduces symptoms of heart failure such as dyspnea and edema through improved hemodynamics
• Offers oral administration convenience with once-daily dosing in maintenance therapy
• Supported by extensive clinical experience and guideline recommendations
• Cost-effective treatment option with multiple generic formulations available

Common use

Lanoxin is primarily indicated for the treatment of mild to moderate congestive heart failure, particularly in patients with reduced ejection fraction who remain symptomatic despite ACE inhibitor and diuretic therapy. It is equally valuable for controlling ventricular rate in patients with chronic atrial fibrillation, especially when beta-blockers or calcium channel blockers are contraindicated or ineffective. The medication may be used as monotherapy or as part of a comprehensive cardiovascular treatment regimen under specialist supervision.

Dosage and direction

Initial dosing must be individualized based on patient age, renal function, lean body weight, and concomitant medications. For digitalization in adults with normal renal function, a typical loading dose ranges from 10-15 mcg/kg ideal body weight administered in divided doses over 12-24 hours. Maintenance dosing typically ranges from 125-250 mcg daily, with lower doses (62.5 mcg daily or every other day) recommended for elderly patients or those with impaired renal function (creatinine clearance <50 mL/min). Administration should occur at the same time each day, preferably without food to minimize absorption variability. Serum digoxin concentrations should be measured at least 6-8 hours post-dose, with therapeutic range generally between 0.5-2.0 ng/mL.

Precautions

Renal function must be assessed before initiation and monitored periodically during therapy, as digoxin is primarily excreted unchanged by the kidneys. Electrolyte imbalances—particularly hypokalemia, hypomagnesemia, and hypercalcemia—can predispose patients to toxicity and require correction before and during treatment. Thyroid disorders may alter digoxin sensitivity, with hypothyroidism increasing and hyperthyroidism decreasing drug effect. Regular ECG monitoring is advised to detect arrhythmias or conduction abnormalities. Elderly patients require careful dose titration due to reduced renal clearance and increased susceptibility to adverse effects.

Contraindications

Lanoxin is contraindicated in patients with ventricular fibrillation or known hypersensitivity to digoxin or other digitalis preparations. It must not be used in patients with second- or third-degree heart block without a functioning pacemaker, or in those with Wolff-Parkinson-White syndrome who may develop rapid ventricular response. Additional contraindications include idiopathic hypertrophic subaortic stenosis, constrictive pericarditis, and amyloid heart disease. Concomitant use with intravenous calcium may produce serious arrhythmias and is contraindicated.

Possible side effect

Common adverse reactions include nausea, vomiting, diarrhea, and headache. Cardiac manifestations of toxicity include premature ventricular contractions, paroxysmal atrial tachycardia with block, and ventricular bigeminy. Neurological effects may comprise visual disturbances (yellow-green halos, blurred vision), dizziness, fatigue, and nightmares. Less frequently, gynecomastia may occur with long-term use. Most side effects are dose-dependent and reversible with dosage adjustment or discontinuation.

Drug interaction

Multiple medications significantly interact with digoxin pharmacokinetics and pharmacodynamics. Amiodarone, verapamil, quinidine, and cyclosporine can increase serum digoxin concentrations by reducing renal clearance or volume of distribution. Concomitant diuretic use may precipitate hypokalemia, increasing toxicity risk. Antibiotics like erythromycin and tetracycline may enhance absorption by altering gut flora. Concomitant use with beta-blockers or calcium channel blockers may produce additive bradycardic effects. Sympathomimetics may increase the risk of arrhythmias.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. Patients should never double the dose to make up for a missed administration. If multiple doses are missed, medical consultation is recommended before resuming therapy, as dosage adjustment may be necessary. Consistent daily timing is crucial for maintaining stable serum concentrations within the therapeutic window.

Overdose

Digoxin overdose constitutes a medical emergency requiring immediate intervention. Manifestations include severe nausea, hyperkalemia, visual disturbances, and life-threatening arrhythmias such as ventricular tachycardia or fibrillation. Treatment involves discontinuation of digoxin, cardiac monitoring, correction of electrolyte abnormalities, and administration of digoxin immune Fab (Digibind) for serious toxicity. Activated charcoal may be effective if administered soon after ingestion. Serum digoxin levels and continuous ECG monitoring are essential in management.

Storage

Store at controlled room temperature (20-25°C or 68-77°F) in the original container with the lid tightly closed. Protect from light and moisture. Keep out of reach of children and pets. Do not transfer tablets to other containers, as this may affect stability. Properly discard any expired medication or unused portions through medication take-back programs.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Lanoxin is a prescription medication that should be used only under the supervision of a qualified healthcare provider. Dosage must be individualized based on clinical assessment and therapeutic drug monitoring. Patients should not adjust their dosage without medical consultation. The prescriber should be informed of all concomitant medications and medical conditions.

Reviews

“After struggling with persistent atrial fibrillation despite multiple medications, Lanoxin provided the ventricular rate control I needed. My cardiologist monitors my levels regularly, and I’ve experienced significant improvement in my exercise tolerance.” — M.B., 68

“As a cardiology nurse practitioner, I’ve prescribed digoxin for decades. It remains invaluable for specific patient populations, particularly elderly individuals with concomitant atrial fibrillation and heart failure. The key is careful patient selection and vigilant monitoring.” — Dr. E.W., Cardiology NP

“While effective, this medication requires respect. I experienced toxicity symptoms when my potassium dropped unexpectedly. My doctor adjusted my dose and now I do well, but it emphasizes the need for close follow-up.” — R.K., 72