CC Pharm | Amiodarone

Amiodarone (Cordarone) Clinical 80/20 Summary 1. Mechanism & Physiological Effects (The 20% Science) Multiclass Action: Class III antiarrhythmic (potassium blocker delaying phase 2/3 repolarization and prolonging refractory period). Also exhibits Class I (sodium blockade slowing phase 0), Class II (noncompetitive alpha/beta-blockade), and Class IV (calcium blockade) properties. Hemodynamics: Relaxes smooth/cardiac muscle, decreasing peripheral/coronary vascular resistance and afterload, reducing myocardial oxygen demand (MVO2). 2. Clinical Uses & Key Dosing Ventricular Arrhythmias (ACLS): For pulseless VF/VT: 300 mg IV/IO push, then 150 mg if refractory. Stable VT / Wide-Complex Tachycardia: 150 mg IV over 10 min, then 1 mg/min for 6 hours, then 0.5 mg/min maintenance. Atrial Fibrillation/Flutter (Off-Label): Rate control and conversion. Oral Dosing: Slow absorption and massive tissue distribution require large loading (800–1600 mg/day for 1–3 weeks) before maintenance of 200–400 mg/day. 3. Critical Toxicities & Warnings (The High-Risk 20%) Pulmonary Toxicity: Fatal pneumonitis or alveolar/pulmonary fibrosis (up to 17% incidence; 10% mortality). Monitor baseline and regular PFTs and chest X-rays. Hepatotoxicity: Can cause severe liver injury. Monitor transaminases; hold or reduce dose if LFTs exceed 3x upper limit of normal. Thyroid Dysfunction: Amiodarone is 37% iodine by weight and blocks T4-to-T3 conversion. Can cause hypo- or hyperthyroidism (thyrotoxicosis). Monitor TSH. Cardiotoxicity: Bradycardia, AV blocks, and QT prolongation leading to Torsade de Pointes. Contraindicated in sick sinus syndrome and 2nd/3rd-degree block without a pacemaker. Ocular/Dermatologic: Corneal microdeposits (common), photosensitivity, and blue-gray skin discoloration. 4. Nursing & Administration Pearls Infusion Safety: Concentrations >2 mg/mL cause severe phlebitis; use a central line for infusions >1 hour. Always use an in-line filter and volumetric pump. Incompatibility: Adsorbs to PVC (dosing accounts for this) and leaches toxic DEHP plasticizers from PVC tubing. Use glass or polyolefin containers for infusions >2 hours. Pharmacokinetics: Highly lipophilic; volume of distribution is ~70 L/kg. Terminal half-life averages 53 days (range 26–107 days). Effects and interactions (inhibits CYP3A4, CYP2C9, P-gp) persist for months after stopping. Client Education: Take consistently with/without food. Report new dyspnea or cough immediately. Wear sunscreen. Follow up for ophthalmic, thyroid, and liver testing.