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Amiodarone
- indication:Intravenously, for initiation of treatment and prophylaxis of frequently recurring ventricular fibrillation and hemodynamically unstable ventricular tachycardia in patients refractory to other therapy. Orally, for the treatment of life-threatening recurrent ventricular arrhythmias such as recurrent ventricular fibrillation and recurrent hemodynamically unstable ventricular tachycardia.
- pharmacologypharmacology:
- mechanism: The antiarrhythmic effect of amiodarone may be due to at least two major actions. It prolongs the myocardial cell-action potential (phase 3) duration and refractory period and acts as a noncompetitive a- and b-adrenergic inhibitor.
- toxicity: Intravenous, mouse: LD<sub>50</sub> = 178 mg/kg. Some side effects have a significant mortality rate: specifically, hepatitis, exacerbation of asthma and congestive failure, and pneumonitis.
- absorprion: Slow and variable (about 20 to 55% of an oral dose is absorbed).
- halflife: 58 days (range 15-142 days)
- roouteelimination: Amiodarone is eliminated primarily by hepatic metabolism and biliary excretion and there is negligible excretion of amiodarone or DEA in urine.
- volumedistribution:
- clearance: * 90-158 mL/h/kg [Healthy with a single dose IV (5 mg/kg over 15 min)] * 100 mL/h/kg [Normal subjects > 65 yrs] * 150 mL/h/kg [younger subjects] * 220 and 440 mL/h/kg [patients with VT and VF]