Amiodarone Hydrochloride

Clinical summary

Indications and usage 1 INDICATIONS AND USAGE Amiodarone hydrochloride tablets are indicated for the treatment of documented, life-threatening recurrent ventricular fibrillation and life-threatening recurrent hemodynamically unstable tachycardia in adults who have not responded to adequate doses of other available antiarrhythmics or when alternative agents cannot be tolerated. Amiodarone hydrochloride tablets is an antiarrhythmic indicated for: Recurrent ventricular fibrillation. ( 1 ) Recurrent hemodynamically unstable ventricular tachycardia. ( 1 ) Dosage and administration 2 DOSAGE AND ADMINISTRATION Dosage must be individualized based on severity of arrhythmia and response. Use the lowest effective dose. Obtain baseline chest x-ray, pulmonary function tests, thyroid function tests, and liver aminotransferases. Correct hypokalemia, hypomagnesemia, and hypocalcemia before initiating treatment Initiate treatment with a loading doses of 800 to 1600 mg/day until initial therapeutic response occurs (usually 1 to 3 weeks). Once adequate arrhythmia control is achieved, or if side effects become prominent, reduce amiodarone hydrochloride tablets dose to 600 to 800 mg/day for one month and then to the maintenance dose, usually 400 mg/day. ( 2 ) Recommended Dosage: Initiate treatment with a loading doses of 800 to 1600 mg/day until initial therapeutic response occurs (usually 1 to 3 weeks). Once adequate arrhythmia control is achieved, or if side effects become prominent, reduce amiodarone hydrochloride tablets dose to 600 to 800 mg/day for one month and then to the maintenance dose, usually 400 mg/day. Administration: Administer amiodarone hydrochloride tablets consistently with regard to meals [see Clinical Pharmacology (12.3) ] . Administration of amiodarone hydrochloride tablets in divided doses with meals is suggested for total daily doses of 1000 mg or higher, or when gastrointestinal intolerance occurs. Warnings and cautions 5 WARNINGS AND PRECAUTIONS Persistence of Adverse Effects: Adverse reactions and drug interaction can persist for several weeks following discontinuation. ( 5.1 ) Impaired Vision: Corneal microdeposits (common; reversible), optic neuropathy/neuritis (rare; may lead to blindness). ( 5.5 ) Thyroid Abnormalities: Hyperthyroidism or hypothyroidism. ( 5.6 ) 5.1 Persistence of Adverse Effects Because of the long half-life of amiodarone (15 to 142 days) and its active metabolite desethylamiodarone (14 to 75 days), adverse reactions and drug interactions can persist for several weeks following amiodarone discontinuation [see Clinical Pharmacology (12.3) ] . 5.2 Pulmonary Toxicity Amiodarone hydrochloride tablets may cause a clinical syndrome of cough and progressive dyspnea accompanied by functional, radiographic, gallium-scan, and pathological data consistent with pulmonary toxicity. Pulmonary toxicity secondary to amiodarone hydrochloride tablets may result from either indirect or direct toxicity as represented by hypersensitivity pneumonitis (including eosinophilic pneumonia) or interstitial/alveolar pneumonitis, respectively. Rates of pulmonary toxicity have been reported to be as high as 17% and is fatal in about 10% of cases. Obtain a baseline chest X-ray and pulmonary-function tests, including diffusion capacity, when amiodarone hydrochloride tablets therapy is initiated. Repeat history, physical exam, and chest X-ray every 3 to 6 months or if symptoms occur. Consider alternative antiarrhythmic therapy if the patient experiences signs or symptoms of pulmonary toxicity. Prednisone 40 to 60 mg/day tapered over several weeks may be helpful in treating pulmonary toxicity. Adult Respiratory Distress Syndrome (ARDS) Postoperatively, occurrences of ARDS have been reported in patients receiving amiodarone hydrochloride tablets therapy who have undergone either cardiac or noncardiac surgery. Although patients usually respond well to vigorous respiratory therapy, in rare instances the outcome has been fatal. 5.3 Hepatic Injury Asymptomatic elevations of hepatic enzyme levels are seen frequently, but amiodarone hydrochloride tablets can cause life-threatening hepatic injury. Histology has resembled that of alcoholic hepatitis or cirrhosis. Obtain baseline and periodic liver transaminases. If transaminases exceed three times normal, or doubles in a patient with an elevated baseline, discontinue or reduce dose of amiodarone hydrochloride tablets, obtain follow-up tests and treat appropriately. 5.4 Worsened Arrhythmia Amiodarone hydrochloride tablets can exacerbate the presenting arrhythmia in about 2 to 5% of patients or cause new ventricular fibrillation, incessant ventricular tachycardia, increased resistance to cardioversion, and polymorphic ventricular tachycardia associated with QTc prolongation (Torsade de Pointes [TdP]). Correct hypokalemia, hypomagnesemia, and hypocalcemia before initiating treatment with amiodarone hydrochloride tablets, as these disorders can exaggerate the degree of QTc