LANOXIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for LANOXIN (LANOXIN).
Inhibits Na+/K+ ATPase, increasing intracellular Ca2+ via Na+/Ca2+ exchange, enhancing cardiac contractility and reducing conduction through AV node.
| Metabolism | Primarily hepatic via CYP3A4 and renal excretion of unchanged drug; undergoes biliary excretion and enterohepatic recirculation. |
| Excretion | Renal excretion of unchanged drug (60-80%) and biliary/fecal elimination (20-40%). |
| Half-life | Terminal elimination half-life is approximately 36-48 hours in patients with normal renal function; prolonged to 3.5-5 days in anuria. |
| Protein binding | 25-30% bound primarily to albumin. |
| Volume of Distribution | Vd approximately 6-7 L/kg; indicates extensive tissue binding, particularly to cardiac muscle. |
| Bioavailability | Oral: 60-80%; Intravenous: 100%. |
| Onset of Action | Oral: 0.5-2 hours; Intravenous: 5-30 minutes. |
| Duration of Action | Oral: 3-6 days; Intravenous: 3-6 days; clinical effects persist as long as drug is present. |
| Molecular Weight | 780.9 |
| Action Class | Cardiac glycosides |
| Brand Substitutes | Digitran 0.25mg Tablet, Sangoxin 0.25mg Tablet, Cardioxin 0.25mg Tablet, Digoxin 0.25mg Tablet, Geoxin 0.25mg Tablet |
0.125-0.25 mg orally once daily; loading dose 0.5-0.75 mg orally divided over 24-48 hours if rapid digitalization required.
| Dosage form | INJECTABLE |
| Renal impairment | GFR >50 mL/min: no adjustment; GFR 10-50 mL/min: reduce dose by 50% or use 0.125 mg every 48 hours; GFR <10 mL/min: reduce dose by 75% or use 0.0625 mg daily; monitor digoxin levels. |
| Liver impairment | No specific Child-Pugh based dose adjustment; use caution in severe hepatic impairment due to potential toxicity; monitor levels. |
| Pediatric use | Loading dose: 10-15 mcg/kg orally divided every 8 hours over 24 hours; maintenance: 5-10 mcg/kg/day orally in 2 divided doses; maximum 0.25 mg/day. |
| Geriatric use | Start with 0.0625-0.125 mg orally daily; adjust based on renal function and drug levels; due to decreased lean body mass and renal clearance. |
| 1st trimester | Use only if clearly needed; risk of fetal bradycardia and low birth weight. Considered safe at therapeutic doses for maternal conditions. |
| 2nd trimester | Continue if maternal benefit outweighs risk; monitor fetal heart rate. No major teratogenicity reported. |
| 3rd trimester | Monitor fetal heart rate and neonatal ECG at delivery; risk of neonatal digitalis toxicity and bradycardia. |
Clinical note
Comprehensive clinical and safety monograph for LANOXIN (LANOXIN).
| Placental transfer | Crosses placenta; cord blood levels similar to maternal serum levels. Fetal concentrations approximate 50-100% of maternal levels. |
| Breastfeeding | Digoxin is excreted into breast milk in low concentrations (0.5-1 ng/mL). Amount ingested by infant is subtherapeutic; considered compatible with breastfeeding. Monitor infant for bradycardia and feeding difficulties. |
■ FDA Black Box Warning
None; however, toxicity is common and potentially fatal. Not a formal black box warning due to age of drug.
| Serious Effects |
Ventricular fibrillationHypersensitivity to digoxin or other digitalis glycosidesDigitalis toxicityWolff-Parkinson-White syndrome with atrial fibrillation (risk of accelerated conduction)Intermittent complete heart block or second-degree AV blockHypertrophic obstructive cardiomyopathy (may worsen obstruction)Constrictive pericarditis (may cause increased diastolic pressures)
| Precautions | Toxicity risk: hypokalemia, hypomagnesemia, hypercalcemia increase sensitivity, Renal impairment requires dose adjustment, Digoxin immune Fab for life-threatening overdose, Pregnancy category C, Monitor serum levels and ECG |
| Food/Dietary | High-fiber foods (bran) may decrease absorption; take digoxin 2 hours before or after high-fiber meals. Potassium-rich foods (bananas, oranges, spinach) can affect toxicity risk; maintain consistent intake. Avoid excessive licorice (glycyrrhizin can cause hypokalemia). Grapefruit juice may increase digoxin absorption; avoid large amounts. |
Loading safety data…
| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | Digoxin crosses the placenta. First trimester: No increased risk of major malformations reported in human studies; animal studies show no teratogenicity at clinically relevant doses. Second/third trimester: Risk of fetal toxicity (bradycardia, arrhythmias) if maternal serum levels are supratherapeutic; therapeutic maternal levels are generally safe. Chronic use may be associated with reduced birth weight. |
| Fetal Monitoring | Maternal: Serum digoxin levels (therapeutic range 0.5–2.0 ng/mL), renal function, electrolytes (especially potassium, magnesium, calcium), ECG for rhythm and signs of toxicity, symptoms of toxicity (nausea, visual disturbances, arrhythmias). Fetal: Ultrasound for heart rate and rhythm, fetal heart rate monitoring in cases of high maternal doses or toxicity. |
| Fertility Effects | Digoxin has no known direct adverse effects on fertility in males or females. However, the underlying cardiac condition being treated may impact fertility; optimal disease control is recommended. |
| Clinical Pearls | Check serum digoxin level 6-8 hours after last dose; therapeutic range 0.5-2.0 ng/mL. Hypokalemia, hypomagnesemia, hypercalcemia increase toxicity risk. Use with caution in renal impairment (reduce dose). Monitor for bradycardia and arrhythmias. Avoid in patients with AV block (except pacemaker) or hypertrophic cardiomyopathy. Loading dose: 10-15 mcg/kg lean body weight. Maintenance: 0.125-0.25 mg daily. Consider drug interactions with amiodarone, verapamil, quinidine, and macrolides. |
| Patient Advice | Take digoxin exactly as prescribed, usually once daily. Do not miss doses or double up. · Monitor pulse before each dose; hold and contact prescriber if heart rate <60 bpm. · Report symptoms of toxicity: nausea, vomiting, diarrhea, blurred vision, yellow-green halos, confusion, or irregular heartbeat. · Avoid over-the-counter antacids, laxatives, or kaolin-pectin; they reduce absorption. Take digoxin 2 hours apart from such products. · Maintain consistent intake of potassium-rich foods (bananas, oranges) unless otherwise instructed. Avoid excessive salt substitutes. · Keep all appointments for blood tests (digoxin levels, potassium, kidney function). · Store at room temperature away from light and moisture. |