Digoxin (Lanoxin): 6 Key Facts, Dosage & Side Effects
Comprehensive guide to Digoxin (Lanoxin): uses, dosage, side effects, and safety for heart failure and arrhythmias.
Digoxin, sold under the brand name Lanoxin, is a cardiac glycoside medication primarily used to treat heart failure and control heart rate in patients with atrial fibrillation. It works by increasing the force of heart contractions and slowing the heart rate, improving symptoms and quality of life.
About Digoxin Tablets
Digoxin tablets are oral formulations of this cardiac glycoside derived from Digitalis lanata. They are indicated for adults with mild to moderate heart failure, where they enhance myocardial contractility, increase left ventricular ejection fraction, and reduce hospitalizations. In chronic atrial fibrillation, digoxin controls the ventricular response rate at rest. Unlike some heart failure treatments, digoxin does not affect mortality but improves exercise capacity and symptoms when combined with diuretics and ACE inhibitors.
The medication has a narrow therapeutic index, meaning the effective dose is close to the toxic dose, requiring careful monitoring of serum levels, electrolytes, and renal function. Peak serum concentrations occur 1-3 hours after oral administration, with 60-80% bioavailability.
Key Facts
- Drug group: Cardiac glycoside.
- Used for: Heart failure (adults and children), atrial fibrillation/flutter, paroxysmal atrial tachycardia.
- Available as: Tablets (62.5 mcg, 125 mcg, 250 mcg), elixir, injection.
- Is it available on the NHS? Yes (common prescription).
- Common brands: Lanoxin.
- Therapeutic effects: Positive inotropic (increases contractility), negative chronotropic (slows heart rate).
About Heart Failure and Atrial Fibrillation
Heart Failure
Heart failure occurs when the heart cannot pump blood effectively, leading to fatigue, shortness of breath, and fluid buildup. Digoxin is used for mild to moderate cases, particularly in patients already on standard therapies. Clinical trials like RADIANCE and PROVED showed digoxin preserved exercise capacity and reduced worsening heart failure events in NYHA class II-III patients. It is often combined with diuretics and ACE inhibitors.
Atrial Fibrillation
Atrial fibrillation (AF) is an irregular heartbeat that can lead to rapid ventricular rates. Digoxin slows conduction through the AV node, controlling resting heart rate without converting AF to sinus rhythm. It is FDA-approved for chronic AF in adults.
How and When to Take Digoxin
Take digoxin exactly as prescribed, usually once or twice daily. Tablets can be taken with or without food, but food may slow absorption without reducing total uptake. Do not adjust dose without consulting a doctor. For elixir, use the provided syringe for accurate measurement.
| Form | Dosage | Frequency |
|---|---|---|
| Adults (Heart Failure Loading) | Digitalizing: 0.75-1.25 mg over 24 hrs; Maintenance: 0.125-0.25 mg daily | Adjust for renal function |
| Adults (AF Rate Control) | 0.125-0.25 mg daily | Titrate to heart rate 60-80 bpm at rest |
| Pediatrics | Neonates: 20-30 mcg/kg; Older children: 10-15 mcg/kg daily | Divide doses |
Missed dose: Take as soon as remembered unless near next dose; do not double. Overdose: Seek emergency help immediately.
Dosage
Dosing is individualized based on age, renal function, and indication. Use ideal body weight for obese patients. Reduce dose in renal impairment. Therapeutic serum levels: 0.5-2 ng/mL; toxicity risk increases above 2 ng/mL. Monitor levels 6-8 hours post-dose.
How Digoxin Works
Digoxin inhibits the Na+/K+ ATPase pump, increasing intracellular sodium and calcium, which enhances myocardial contractility (positive inotropic effect). It also prolongs the AV node refractory period (negative chronotropic and dromotropic effects), slowing ventricular rate in AF. Additional effects include increased baroreceptor sensitivity and sympathetic withdrawal. Peak cardiac effects occur 3-6 hours post-ingestion.
Common Questions
- Can you take digoxin on an empty stomach? Yes, but with food if stomach upset occurs.
- Can you take digoxin before bed? Yes, if it fits your schedule.
- Is digoxin a blood thinner? No, it controls heart rate/contractility.
- Does digoxin lower blood pressure? It may indirectly via heart rate control.
- Can digoxin cause weight gain? No, but monitor for fluid retention in heart failure.
- Is digoxin a diuretic? No.
- Can you drink alcohol with digoxin? Limit alcohol; it may worsen side effects.
Cautions
Use cautiously in hypokalemia, hypomagnesemia, hypercalcemia, renal impairment, hypothyroidism, recent MI, and obesity. Correct electrolytes before starting. Avoid in Wolff-Parkinson-White syndrome, ventricular fibrillation, or hypersensitivity.
Side Effects
Most side effects relate to toxicity. Gastrointestinal symptoms (nausea, vomiting, anorexia) occur in up to 80% and often precede cardiac issues.
| System | Common Side Effects | Serious |
|---|---|---|
| Gastrointestinal | Nausea, vomiting, diarrhea, abdominal pain | Intestinal ischemia, necrosis |
| Cardiac | Bradycardia, AV block | Arrhythmias (junctional tachycardia, VT) |
| CNS | Headache, dizziness, confusion | Hallucinations, delirium |
| Visual | Blurry vision, yellow-green halos | Xanthopsia |
| Other | Fatigue, weakness | Gynecomastia (chronic use) |
Serious Side Effects and Toxicity
Digoxin toxicity is common due to narrow therapeutic index. Risk factors: low potassium/magnesium, renal failure, drug interactions. Symptoms: GI upset, visual changes, arrhythmias (e.g., bidirectional VT, AV block). Nearly any arrhythmia can occur.
Treatment: Stop digoxin, correct electrolytes (K+ 4-5.5 mEq/L), monitor ECG. Severe cases: Digoxin immune Fab (Digibind).
Pregnancy and Breastfeeding
Pregnancy: Category C; use if benefits outweigh risks. Crosses placenta; monitor fetus. Breastfeeding: Appears safe in low doses; monitor infant heart rate.
Other Medicines, Food, and Drink
Interactions:
- Increase digoxin levels: Amiodarone, verapamil, macrolides (erythromycin), tetracyclines, diuretics (via hypokalemia).
- Decrease levels: Antacids, cholestyramine, rifampin.
- Electrolyte effects: Diuretics, laxatives (hypokalemia increases toxicity).
- Others: Avoid St. John’s Wort (induces metabolism).
Food: High-fiber meals may reduce absorption. Maintain consistent diet.
Common Brands
- Lanoxin (tablets, injection, elixir).
- Generic digoxin.
Related NHS Content
- Atrial fibrillation information.
- Heart failure management.
- Electrolyte imbalance advice.
Frequently Asked Questions (FAQs)
Q: What is digoxin used for?
A: Digoxin treats heart failure by strengthening contractions and controls heart rate in atrial fibrillation.
Q: How quickly does digoxin work?
A: Oral effects start in hours; peak cardiac effects in 3-6 hours, lasting 24+ hours.
Q: What are signs of digoxin toxicity?
A: Nausea, vomiting, vision changes (yellow halos), confusion, irregular heartbeat. Seek immediate care.
Q: Can children take digoxin?
A: Yes, for heart failure and arrhythmias; dose by weight and monitor closely.
Q: Does digoxin interact with antibiotics?
A: Yes, macrolides and tetracyclines can increase levels by altering gut bacteria.
Q: Is monitoring required with digoxin?
A: Yes, regular blood tests for levels, potassium, renal function, and ECG.
References
- Digoxin (Lanoxin) | Davis’s Drug Guide — Unbound Medicine. 2023. https://nursing.unboundmedicine.com/nursingcentral/view/Davis-Drug-Guide/51218/all/digoxin
- Lanoxin (Digoxin Tablets): Side Effects, Uses, Dosage — RxList. 2023. https://www.rxlist.com/lanoxin-tablets-drug.htm
- LANOXIN (digoxin) tablets Prescribing Information — FDA. 2016-01-01. https://www.accessdata.fda.gov/drugsatfda_docs/label/2016/020405s013lbl.pdf
- Digoxin – StatPearls — NCBI Bookshelf. 2023-07-17. https://www.ncbi.nlm.nih.gov/books/NBK556025/
- Digoxin (oral route) – Mayo Clinic — Mayo Clinic. 2023. https://www.mayoclinic.org/drugs-supplements/digoxin-oral-route/description/drg-20072646
- Digoxin (Lanoxin) – Children’s Minnesota — Children’s Minnesota. 2023. https://www.childrensmn.org/educationmaterials/childrensmn/article/15436/digoxin-lanoxin/
- Digoxin: Uses, Interactions | DrugBank — DrugBank. 2023. https://go.drugbank.com/drugs/DB00390
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