BSN Tracker

amiodarone

Brand: Pacerone, Nexterone

⚠ BBW ISMP High Alert Prototype Drug
Drug Class: antiarrhythmic (Class III)
Drug Family: antiarrhythmic
Subclass: iodinated benzofuran (multi-channel blocker)
Organ Systems: cardiovascular

Mechanism of Action

Complex Class III antiarrhythmic inhibiting multiple channels; major effect is potassium channel blockade prolonging action potential; also blocks Na+, Ca2+, and beta-receptors; high iodine content causes thyroid effects.

potassium channels (IKr, IKs)sodium channelscalcium channelsbeta-adrenergic receptors (non-competitive)

Indications

  • ventricular fibrillation/VT (ACLS)
  • atrial fibrillation/flutter
  • prevention of recurrent VT/VF

Contraindications

  • cardiogenic shock
  • sinus bradycardia with syncope
  • sino-atrial block
  • 2nd/3rd degree AV block
  • iodine hypersensitivity
  • thyroid disease (relative)

Adverse Effects

Common

  • bradycardia
  • hypotension (IV)
  • photosensitivity
  • blue-gray skin discoloration
  • GI upset

Serious

  • pulmonary toxicity (fibrosis)
  • hepatotoxicity
  • thyroid dysfunction (hyper- or hypothyroidism)
  • peripheral neuropathy
  • proarrhythmia (TdP, rare)
  • optic neuropathy

Pharmacokinetics (ADME)

Absorption 22-86% oral (extremely variable)
Distribution extremely large Vd (60 L/kg) — stored in fat, liver, lungs
Metabolism hepatic CYP3A4, CYP2C8; desethylamiodarone active metabolite
Excretion fecal (biliary)
Half-life 40-55 days (very long)
Onset days to weeks (oral)
Peak 3-7 hours
Duration months
Protein Binding 99%
Vd 60 L/kg

Drug Interactions

Drug / Agent Mechanism Severity
warfarin inhibits CYP2C9 — increases INR significantly (reduce warfarin dose 30-50%) major
digoxin increases digoxin levels 70% (inhibits P-gp and CYP3A4) major
simvastatin inhibits CYP3A4 — rhabdomyolysis risk major
many QT-prolonging drugs additive QT prolongation major

Nursing Considerations

  1. Pulmonary toxicity monitoring: annual CXR and PFTs; report new dyspnea
  2. Thyroid function tests q6 months (contains 37% iodine by weight; 200mg tablet → 75mg inorganic iodine)
  3. LFTs q6 months; corneal microdeposits (virtually all patients — benign)
  4. Reduce warfarin dose by 30-50% — check INR weekly until stable
  5. IV loading: 150 mg over 10 min, then 1 mg/min × 6h, then 0.5 mg/min × 18h

Clinical Pearls

  • 40-55 day half-life: weeks to months to reach steady state; adverse effects persist after discontinuation
  • Thyroid: 37% iodine by weight — inhibits thyroid hormone synthesis (hypothyroidism) OR triggers autonomous thyroid hormone release (hyperthyroidism); both occur
  • Most effective antiarrhythmic but toxicity limits chronic use

Safety Profile

Pregnancy avoid
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Required
TDM Not required

Concordance Terms

Cross-referenced clinical concepts — click any term to see all content where it appears.

Antiarrhythmic (Class III) Atrial Fibrillation/flutter Prevention Of Recurrent VT/VF Ventricular Fibrillation/VT (ACLS)
← Back to Medications