| Drug class |
Cardiac glycoside (digoxin) |
| Common indications |
1. Chronic heart failure (to improve symptoms and exercise tolerance)
2. Atrial fibrillation or atrial flutter (rate control, especially if the patient has heart failure or poor LV function) |
| Typical oral dose |
• 0.25 mg once daily (often the starting dose for adults)
• Dose may be adjusted (up or down) based on serum digoxin levels, renal function, and clinical response |
| Mechanism of action |
• Inhibits Na⁺/K⁺‑ATPase → ↑ intracellular Na⁺ → ↑ Ca²⁺ via Na⁺/Ca²⁺ exchanger → stronger myocardial contraction (positive inotropy).
• Modulates autonomic tone → ↓ heart rate (negative chronotropy) in atrial fibrillation/flutter. |
| Pharmacokinetics |
• Bioavailability: ~70–80 % (oral).
• Peak serum level: ~6–12 h after a dose.
• Half‑life: ~36–48 h in normal renal function (longer in CKD).
• Primary elimination: renal (≈80 %). |
| Monitoring |
• Serum digoxin level (therapeutic range 0.5–2.0 ng/mL; >2 ng/mL increases risk of toxicity).
• Electrolytes, especially potassium and magnesium (hypokalemia or hypomagnesemia ↑ toxicity risk).
• Renal function (creatinine, eGFR).
• ECG (especially for bradycardia, ventricular arrhythmias). |
| Common adverse effects |
• GI: nausea, vomiting, anorexia, abdominal pain.
• CNS: headache, dizziness, confusion, visual disturbances (blurred vision, yellow‑green halos).
• Cardiac: bradycardia, AV block, arrhythmias (ventricular ectopy, tachyarrhythmias). |
| Drug interactions |
• Potassium‑sparing diuretics, ACE inhibitors, ARBs, potassium supplements – ↑ serum potassium → ↑ digoxin toxicity.
• Amiodarone, verapamil, diltiazem, quinidine – ↑ digoxin levels.
• Probenecid, cyclosporine, NSAIDs – ↓ excretion → ↑ levels.
• Beta‑blockers – can mask bradycardia symptoms. |
| Contraindications |
• Digoxin toxicity (elevated serum level or arrhythmias).
• Severe renal impairment (eGFR < 30 mL/min) unless dose adjustment and close monitoring.
• Hypokalemia or hypomagnesemia (unless corrected). |
| Patient counseling |
• Take on an empty stomach or with a light meal; avoid foods high in potassium (bananas, oranges) or potassium‑sparing diuretics unless advised.
• Monitor for signs of toxicity: nausea, vomiting, visual changes, dizziness, irregular heartbeat, confusion.
• Keep regular appointments for blood tests (serum digoxin, electrolytes, renal function).
• Report any new medications, especially OTC or herbal supplements. |
| Pregnancy & lactation |
• Category B (no evidence of risk in humans).
• Use only if benefits outweigh risks; discuss with healthcare provider.
• Low transfer into breast milk – generally considered safe but consult your clinician. |
| Storage |
• Store at 20–25 °C (room temperature), protected from moisture and light.
• Keep out of reach of children. |