Digoxin

• Maternal AF/flutter rate control
• Fetal SVT with hydrops (transplacental)
• Systolic HF adjunct

Inhibits Na⁺/K⁺ ATPase → ↑ intracellular Ca²⁺ → positive inotropy; enhances vagal tone → AV nodal slowing.

• Therapeutic 0.8–2 ng/mL (heart failure ≤1.2)
• Toxicity worsened by hypokalaemia, hypomagnesaemia, renal impairment
• Digibind = digoxin-specific Fab

Loading (adult)

0.75–1.5 mg total PO/IV in divided doses over 24 h

Maintenance

125–250 μg OD (adjust for renal function)

Fetal SVT

Maternal 0.25 mg TDS after load, target level 2 ng/mL

• Absolute2°/3° AV block (without pacing)
• AbsoluteWPW with AF (accelerates conduction)
• AbsoluteHypertrophic obstructive cardiomyopathy

• Nausea, anorexia (early toxicity)
• Yellow-green visual haloes
• Bradyarrhythmias / any arrhythmia
• Confusion

• • Crosses placenta well — used therapeutically for fetal SVT
• • No teratogenic signal
• • Compatible with breastfeeding

• Amiodarone / verapamil / quinidine

  Avoid

  ↑ digoxin levels — halve dose

• Diuretics

  Caution

  Hypokalaemia potentiates toxicity

• Erythromycin / clarithromycin

  Caution

  ↑ digoxin levels

• 💡 Take trough sample ≥6 h post-dose
• 💡 In toxicity: correct K⁺/Mg²⁺, atropine for bradycardia, Fab fragments for arrhythmia/hyperK/level >10