1. Clinical & Scientific Overview
Digoxin (TIP-MED-000021, Reference Code [3.21]) is classified under
Cardiovascular & Antithrombotic Medicines (Ch 03) as a Cardiac Glycoside (Na+/K+-ATPase Pump Inhibitor); Positive Inotrope & Vagal AV Nodal Blocker.
Within the Indian regulatory and compendial framework, it is governed under Schedule H Prescription Drug (To be sold by retail on the prescription of a Registered Medical Practitioner only — Drugs Rules 1945).
Representative Indian Market Examples (Edition 2.7 Ch 03 [3.21], p. 31): Lanoxin (GSK/Aspen), Dixin (Samarth Life Sciences), Cardioxin — Strengths & Dosage Forms: Oral Uncoated Scored Tablets: 0.25 mg (250 mcg); Paediatric Elixir: 0.05 mg/mL (50 mcg/mL); Injection: 0.25 mg/mL (2 mL = 0.5 mg)
Oral Uncoated Scored Tablets: 0.25 mg (250 mcg); Paediatric Elixir: 0.05 mg/mL (50 mcg/mL); Injection: 0.25 mg/mL (2 mL = 0.5 mg)
3. Mechanism of Action & Pharmacodynamics
Cardiac Glycoside (Na+/K+-ATPase Pump Inhibitor); Positive Inotrope & Vagal AV Nodal Blocker acting on target receptor/enzyme pathways in Cardiovascular & Antithrombotic Medicines (Ch 03): clinical efficacy is mediated via Cardiac Glycoside (Na+/K+-ATPase Pump Inhibitor); Positive Inotrope & Vagal AV Nodal Blocker for Ventricular rate control in chronic atrial fibrillation / atrial flutter (especially in sedentary patients or with concomitant HFrEF); symptomatic chronic heart failure with reduced ejection fraction (HFrEF) refractory to guideline-directed medical therapy..
4. Therapeutic Indications & Evidence-Supported Uses
- Ventricular rate control in chronic atrial fibrillation / atrial flutter (especially in sedentary patients or with concomitant HFrEF)
- symptomatic chronic heart failure with reduced ejection fraction (HFrEF) refractory to guideline-directed medical therapy
5. Educational Dosage Context, Formulations & Administration
Educational Dosing & Regimen Summary: General Adult Reference: Narrow Therapeutic Index! Maintenance dosing is strictly individualised by the treating clinician based on indication (HFrEF vs. AF), age, lean body weight, and renal function (CrCl): typically 0.0625 mg (62.5 mcg) to 0.125 mg (125 mcg) once daily (or 0.0625 mg every other day in renal impairment/frail elderly; rarely 0.25 mg OD in younger adults with normal renal clearance). Do not assume a universal Monday–Friday schedule; always verify the exact prescribed dose, frequency, and administration days on the prescription.
Administration & Meal Timing: With or without food (avoid taking simultaneously with high-fibre bran meals, which reduce absorption). | Once daily in the morning.
6. Pharmacokinetics, Metabolism & Renal/Hepatic Adjustment
Absorption, distribution, metabolism, and excretion follow class pharmacokinetic profile; verify patient renal/hepatic function.
Renal: Strictly renal-function dependent! Excreted 60–80% unchanged by the kidneys; elimination half-life increases from 36 hours (normal renal function) to 4–6 days in severe CKD/anuria. Dose must be reduced (e.g., 0.0625 mg–0.125 mg daily or alternate days) whenever CrCl <50 mL/min. Hepatic: No major adjustment required.
Renal: Strictly renal-function dependent! Excreted 60–80% unchanged by the kidneys; elimination half-life increases from 36 hours (normal renal function) to 4–6 days in severe CKD/anuria. Dose must be reduced (e.g., 0.0625 mg–0.125 mg daily or alternate days) whenever CrCl <50 mL/min. Hepatic: No major adjustment required.
Renal: Strictly renal-function dependent! Excreted 60–80% unchanged by the kidneys; elimination half-life increases from 36 hours (normal renal function) to 4–6 days in severe CKD/anuria. Dose must be reduced (e.g., 0.0625 mg–0.125 mg daily or alternate days) whenever CrCl <50 mL/min. Hepatic: No major adjustment required.
7. Contraindications, Precautions & High-Risk Warnings
- Contraindicated in ventricular fibrillation, hypertrophic obstructive cardiomyopathy (HOCM), Wolff-Parkinson-White (WPW) syndrome with AF, and 2nd/3rd degree AV block. Toxicity is massively potentiated by hypokalaemia, hypomagnesaemia, hypercalcaemia, and hypothyroidism.
Key Clinical Precautions: Renal: Strictly renal-function dependent! Excreted 60–80% unchanged by the kidneys; elimination half-life increases from 36 hours (normal renal function) to 4–6 days in severe CKD/anuria. Dose must be reduced (e.g., 0.0625 mg–0.125 mg daily or alternate days) whenever CrCl <50 mL/min. Hepatic: No major adjustment required.
8. Adverse Effects Profile
- Often well tolerated within therapeutic serum range (0.5–0.9 ng/mL in HF); mild nausea or fatigue if levels rise.
- Digoxin Toxicity (Serum level >1.2–2.0 ng/mL): Early GI signs: anorexia, nausea, vomiting, abdominal pain. Neurological/Visual signs: confusion, delirium, fatigue, blurred vision, xanthopsia (yellow-green halos around lights). Cardiac signs: severe sinus bradycardia (<50 bpm), AV nodal block, premature ventricular contractions (ventricular bigeminy), paroxysmal atrial tachycardia with block, fatal ventricular tachycardia.
- Monitor for severe hypersensitivity, organ toxicity, or dose-limiting adverse events.
9. Major Drug–Drug, Drug–Food & Drug–Herb Interactions
- P-glycoprotein (P-gp) Inhibitors markedly increase serum digoxin levels by 30–100%: Amiodarone, Verapamil, Diltiazem, Clarithromycin, Erythromycin, Itraconazole, Propafenone, Quinidine, Spironolactone, Telmisartan, Carvedilol, Atorvastatin (reduce digoxin dose by 50% when starting amiodarone or verapamil)
- Loop and thiazide diuretics (furosemide, chlorthalidone) precipitate digoxin toxicity by depleting K+ and Mg2+
- Antacids, sucralfate, and cholestyramine reduce oral absorption
10. Clinical Monitoring, Patient Counselling & Storage
Clinical & Laboratory Monitoring: Monitor clinical response, baseline renal/hepatic parameters, and relevant serum biomarkers.
Pharmacist Patient Counselling Points:
- Patient Counselling Checklist: Clearly mark the tablet strip if the doctor has prescribed the classic '5 days a week (skip Saturday & Sunday)' or 'Half tablet (0.125 mg) daily' schedule—accidental daily full-tablet intake by an elderly patient is a frequent cause of hospitalisation. Teach the caregiver to check the pulse and immediately report loss of appetite, nausea, confusion, or yellow-green tinted vision.
- Meal & Clock Timing Instruction: With or without food (avoid taking simultaneously with high-fibre bran meals, which reduce absorption). (Once daily in the morning.)
- Missed Dose Protocol: If remembered within 12 hours, take the dose; if >12 hours late, skip. Never double a digoxin dose.
- Geriatric Dispensing Pearl: High-Alert Beers Criteria medication in the elderly: doses >0.125 mg/day should generally be avoided due to age-related drop in GFR and lean muscle mass. Always check if the patient is also taking furosemide (hypokalaemia) or amiodarone/telmisartan.
Storage, Stability & Dispensing Safeguards: Store below 25°C–30°C in original moisture- and light-resistant packaging out of reach of children. Available forms: Oral Uncoated Scored Tablets: 0.25 mg (250 mcg); Paediatric Elixir: 0.05 mg/mL (50 mcg/mL); Injection: 0.25 mg/mL (2 mL = 0.5 mg)
11. Visual Pharmacology & Mechanism Diagram (svg-v339-01-adme-12-step-journey)
12. Authoritative References, Regulatory Sources & Editorial Disclaimer
Primary Compendial & Guideline Reference: Indian Pharmacist Desk Reference — Professional Edition 2.7 (2026–27) • Ch 03 [3.21] (p. 31)
Official Verification Portals: Indian Pharmacopoeia Commission (IPC) & National Formulary of India (NFI) • Central Drugs Standard Control Organization (CDSCO) • Ministry of Health & Family Welfare — NLEM 2022 • NCBI Bookshelf / StatPearls Pharmacology Reference • DailyMed (US FDA Official Prescribing Reference)
Last Medically & Pharmaceutically Reviewed: 2026-11-10 • Verification Status: HANDBOOK_SOURCE_CONTENT
Educational & Clinical Disclaimer: This reference profile is published solely for pharmacy education, academic study, and professional clinical reference. It does not substitute for patient-specific clinical judgement, qualified specialist oncology/medical supervision, or official CDSCO/IP prescribing information. Never self-medicate with prescription, Schedule H/H1/X, NDPS, or oncology medicines.