Digoxin

Cardiac Glycoside·Cardiovascular - Antiarrhythmics

Rate control in AF, symptomatic relief in HFrEF

PBSCARDIAC GLYCOSIDELanoxinTablets (62S4+1

Max Dose

500 mcg/day

Half-life

36 h

Toxicity

DOSE-DEP

Target

0.5-0.9 ng/mL

Rapid Summary

Overview

Ancient, narrow therapeutic index agent derived from the foxglove plant. Increases cardiac contractility while strongly slowing the AV node.

Maximum Dose

Max 500 mcg/day (maintenance usually 62.5 - 250 mcg/day).

Clinical Focus

Hypokalemia makes the heart exquisitely sensitive to Digoxin, triggering fatal arrhythmias even at 'normal' blood levels.

Bottom Line

Digoxin is a unique positive inotrope for heart failure and AF rate control, but has an extremely narrow therapeutic index requiring drug level monitoring to avoid fatal toxicity.

Formulation & Access

Brand Names

Lanoxin

Oral Routes

Tablets (62.5 mcg, 250 mcg). Oral Liquid.

Parenteral

Ampoule (500 mcg/2 mL) for IV use.

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Rate control in AF, symptomatic relief in HFrEF.

Clinical Place

Add-on therapy when beta-blockers/CCBs fail or are contraindicated. Does NOT reduce mortality in heart failure, only reduces hospitalisations.

Quick reference

Class & Role

Cardiac Glycoside — Ancient, narrow therapeutic index agent derived from the foxglove plant.

Route / Formulation

Tablets (62.5 mcg, 250 mcg). Oral Liquid. (Lanoxin)

Usual Dose & Max

PO / IV 250-500 mcg. Repeat 250 mcg every 6 hours to a total loading dose of 750-1500 mcg. Max 500 mcg/day (maintenance usually 62.5 - 250 mcg/day).

Key Indication Doses

AF Rate Control (Loading): PO / IV 250-500 mcg. Repeat 250 mcg every 6 hours to a total loading dose of 750-1500 mcg. Maintenance: PO 125-250 mcg OD. Elderly / Renal Impairment: Max 62.5 mcg OD or alternate days if eGFR is poor.

Best Uses

Digoxin is a unique positive inotrope for heart failure and AF rate control, but has an extremely narrow therapeutic index requiring drug level monitoring to avoid fatal toxicity.

Avoid / Cautions

WPW syndrome with AF, 2nd/3rd degree heart block, ventricular tachycardia.

Key Risks

Cardiovascular: Arrhythmias (virtually any type, classically PVCs and bradycardia). Gastrointestinal: Nausea, vomiting, anorexia (often the very first sign of toxicity!). Neurological: Confusion, visual disturbances (yellow-green halos around lights - xanthopsia).

Key Interactions

Amiodarone, Verapamil, and Macrolides double Digoxin levels via P-glycoprotein inhibition. Diuretics (via potassium depletion).

Monitoring

Strict U&E monitoring. Maintain K+ > 4.0 mmol/L. Measure TDM (Digoxin levels) at least 6 hours post-dose (target 0.5-0.9 ng/mL for HF, up to 1.2 for AF). Baseline ECG.

Clinical Pearl

If an elderly patient on Digoxin suddenly loses their appetite or starts vomiting, assume Digoxin toxicity until proven otherwise and withhold the drug.

Access

LanoxinTablets (62

Brand: Lanoxin
Formulation: Tablets (62

Digoxin

Cardiac Glycoside·Cardiovascular - Antiarrhythmics

Rate control in AF, symptomatic relief in HFrEF

PBSCARDIAC GLYCOSIDELanoxinTablets (62S4+1

Max Dose

500 mcg/day

Half-life

36 h

Toxicity

DOSE-DEP

Target

0.5-0.9 ng/mL

Rapid Summary

Overview

Ancient, narrow therapeutic index agent derived from the foxglove plant. Increases cardiac contractility while strongly slowing the AV node.

Maximum Dose

Max 500 mcg/day (maintenance usually 62.5 - 250 mcg/day).

Clinical Focus

Hypokalemia makes the heart exquisitely sensitive to Digoxin, triggering fatal arrhythmias even at 'normal' blood levels.

Bottom Line

Digoxin is a unique positive inotrope for heart failure and AF rate control, but has an extremely narrow therapeutic index requiring drug level monitoring to avoid fatal toxicity.

Formulation & Access

Brand Names

Lanoxin

Oral Routes

Tablets (62.5 mcg, 250 mcg). Oral Liquid.

Parenteral

Ampoule (500 mcg/2 mL) for IV use.

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Rate control in AF, symptomatic relief in HFrEF.

Clinical Place

Add-on therapy when beta-blockers/CCBs fail or are contraindicated. Does NOT reduce mortality in heart failure, only reduces hospitalisations.

Quick reference

Class & Role

Cardiac Glycoside — Ancient, narrow therapeutic index agent derived from the foxglove plant.

Route / Formulation

Tablets (62.5 mcg, 250 mcg). Oral Liquid. (Lanoxin)

Usual Dose & Max

PO / IV 250-500 mcg. Repeat 250 mcg every 6 hours to a total loading dose of 750-1500 mcg. Max 500 mcg/day (maintenance usually 62.5 - 250 mcg/day).

Key Indication Doses

Best Uses

Digoxin is a unique positive inotrope for heart failure and AF rate control, but has an extremely narrow therapeutic index requiring drug level monitoring to avoid fatal toxicity.

Avoid / Cautions

WPW syndrome with AF, 2nd/3rd degree heart block, ventricular tachycardia.

Key Risks

Key Interactions

Amiodarone, Verapamil, and Macrolides double Digoxin levels via P-glycoprotein inhibition. Diuretics (via potassium depletion).

Monitoring

Strict U&E monitoring. Maintain K+ > 4.0 mmol/L. Measure TDM (Digoxin levels) at least 6 hours post-dose (target 0.5-0.9 ng/mL for HF, up to 1.2 for AF). Baseline ECG.

Clinical Pearl

If an elderly patient on Digoxin suddenly loses their appetite or starts vomiting, assume Digoxin toxicity until proven otherwise and withhold the drug.

Access

LanoxinTablets (62

Brand: Lanoxin
Formulation: Tablets (62