Amiodarone Hydrochloride

NEXTERONE is indicated for initiation of treatment and prophylaxis of frequently recurring ventricular fibrillation (VF) and hemodynamically unstable ventricular tachycardia (VT) in patients refractory to other therapy. NEXTERONE is an antiarrhythmic agent indicated for treatment and prophylaxis of ventricular fibrillation (VF) and hemodynamically unstable ventricular tachycardia (VT) in patients refractory to other therapy. (1)

Injection, 1.5 mg/mL (150 mg/100 mL) Premixed in Dextrose Injection, 1.8 mg/mL (360 mg/200 mL) Premixed in Dextrose Injection, 1.5 mg/mL (150 mg/100 mL) Premixed in Dextrose (3) Injection, 1.8 mg/mL (360 mg/200 mL) Premixed in Dextrose (3)

NEXTERONE is contraindicated in patients with:

• Known hypersensitivity to any of the components of NEXTERONE Premixed Injection, including iodine [ see Warnings and Precautions (5.8) ].
• Cardiogenic shock.
• Marked sinus bradycardia.
• Second- or third-degree atrioventricular (AV) block unless a functioning pacemaker is available. NEXTERONE is contraindicated in patients with (4) :
• Known hypersensitivity to any of the components of NEXTERONE, including iodine
• Cardiogenic shock
• Marked sinus bradycardia
• Second- or third-degree atrio-ventricular (AV) block unless a pacemaker is available.

• Hypotension: Slow the infusion; as needed, add vasopressor drugs, positive inotropic agents, and volume expansion. (5.2)
• Bradycardia and AV block: Slow the infusion or discontinue. ( 5.3 )

5.1 Persistence of Adverse Effects Because of the long half-life of amiodarone (9 to 36 days) and its metabolite desethylamiodarone (9 to 30 days), adverse reactions or interactions, as well as observed adverse effects, can persist following amiodarone withdrawal.

5.2 Hypotension Hypotension, the most common adverse reaction seen with intravenous amiodarone seen most often in the first several hours of treatment and is likely related to the rate of infusion. In some cases, hypotension may be refractory and result in a fatal outcome. Hypotension necessitating alterations in intravenous amiodarone therapy was reported in 3% of patients, with permanent discontinuation required in less than 2% of patients. Treat hypotension initially by slowing the infusion; additional standard therapy may be needed, including the following: vasopressor drugs, positive inotropic agents, and volume expansion . Monitor the initial rate of infusion closely and do not exceed the recommended rate [ see Dosage and Administration (2) ].

5.3 Bradycardia and Atrioventricular Block NEXTERONE causes bradycardia and AV block which may require slowing the infusion rate or discontinuing NEXTERONE. In some patients, inserting a pacemaker is required. Have a temporary pacemaker available when treating a patient predisposed to bradycardia or AV block.

5.4 Hepatic Injury Acute hepatocellular necrosis leading to hepatic coma, acute renal failure, and death has been associated with the administration of intravenous amiodarone. Intravenous infusions at much higher concentrations and rates of infusion than those recommended appear to increase this risk [ see Dosage and Administration (2) ]. Carefully monitor patients receiving NEXTERONE for evidence of progressive hepatic injury. Consider reducing the rate of administration or withdrawing NEXTERONE if hepatic injury occurs.

5.5 Proarrhythmia NEXTERONE may cause a worsening of existing arrhythmias or precipitate a new arrhythmia, sometimes leading to fatal outcomes [ see Adverse Reactions (6.2) ]. Proarrhythmia, primarily torsade de pointes (TdP), has been associated with prolongation, by intravenous amiodarone. Although QTc prolongation occurred frequently in patients receiving intravenous amiodarone, TdP or new-onset VF occurred infrequently (less than 2%). Monitor patients for QTc prolongation during infusion with NEXTERONE. Reserve the combination of amiodarone with other antiarrhythmic therapies that prolong the QTc to patients with life-threatening ventricular arrhythmias who are incompletely responsive to a single agent. Correct hypokalemia, hypomagnesemia or hypocalcemia whenever possible before initiating treatment with NEXTERONE, as these disorders can exaggerate the degree of QTc prolongation and increase the potential for TdP. Give special attention to electrolyte and acid-base balance in patients experiencing severe or prolonged diarrhea or in patients receiving concomitant diuretics and laxatives.

5.6 Pulmonary Injury Early-onset Pulmonary Toxicity There have been postmarketing reports of acute-onset (days to weeks) pulmonary injury in patients treated with intravenous amiodarone. Findings have included pulmonary infiltrates and masses on X-ray, pulmonary fibrosis, bronchospasm, wheezing, fever, dyspnea, cough, hemoptysis, and hypoxia. Two percent (2%) of patients were reported to have adult respiratory distress syndrome (ARDS) during clinical studies involving 48 hours of therapy. Some cases have progressed to respiratory failure or death. Monitor for new respiratory symptoms and evaluate appropriately. Obtain a baseline chest X-ray and pulmonary function tests in patients who are expected to be receiving amiodarone chronically.

5.7 Loss of Vision Cases of optic neuropathy and optic neuritis, usually resulting in visual impairment, have been reported in patients treated with oral amiodarone or intravenous amiodarone. In some cases, visual impairment has progressed to permanent blindness. Optic neuropathy and neuritis may occur at any time following initiation of therapy. Perform an ophthalmic examination if symptoms of visual impairment appear, such as changes in visual acuity and decreases in peripheral vision. Re-evaluate the necessity of amiodarone therapy if optic neuropathy or neuritis is suspected.

5.8 Thyroid Abnormalities Nexterone inhibits peripheral conversion of throxine (T4) to triiodothyronine (T3) and may cause increased T3 levels, and increased levels of inactive reverse T3 (rT3) in clinically euthyroid patients. Monitor thyroid function prior to treatment and periodically thereafter, particularly in elderly patients, and in any patient with a history of thyroid nodules, goiter, or other thyroid dysfunction. Hyperthyroidism may induce arrhythmia breakthrough. If any new signs of arrhythmia appear, the possibility of hyperthyroidism should be considered. Antithyroid drugs, β-adrenergic blockers, temporary corticosteroid therapy may be necessary to treat the symptoms of hyperthyroidism. The action of antithyroid drugs may be delayed in amiodarone-induced thyrotoxicosis because of substantial quantities of preformed thyroid hormones stored in the gland. Radioactive iodine therapy is contraindicated because of the low radioiodine uptake associated with amiodarone-induced hyperthyroidism. Nexterone-induced hyperthyroidism may be followed by a transient period of hypothyroidism. In some clinically hypothyroid amiodarone-treated patients, free thyroxine index values may be normal. Manage hypothyroidism by reducing the dose of or discontinuing amiodarone and thyroid hormone supplementation.

5.9 Neonatal Injury Amiodarone can cause fetal harm when administered to a pregnant woman. Fetal exposure may increase the potential for adverse experiences including cardiac, thyroid, neurodevelopmental, neurological and growth effects in neonate. Inform the patient of the potential hazard to the fetus if NEXTERONE is administered during pregnancy or if the patient becomes pregnant while taking NEXTERONE [ see Pregnancy (8.1) ].

5.10 Hypersensitivity Reactions Anaphylactic/anaphylactoid reactions have been reported with intravenous amiodarone including shock (sometimes fatal), cardiac arrest, and the following manifestations: hypotension, tachycardia, hypoxia, cyanosis, rash, Stevens-Johnson syndrome, flushing, hyperhidrosis and cold sweat.

5.11 Phlebitis Infusion site phlebitis has occurred in patients receiving intravenous amiodarone. Intravenous amiodarone concentrations greater than 3 mg/mL have been associated with a high incidence of peripheral vein phlebitis.

The following adverse reactions are described elsewhere in labeling:

• Hypotension [ see Warnings and Precautions (5.2) ]
• Hepatic injury [ see Warnings and Precautions (5.4) ]
• Proarrhythmia [ see Warnings and Precautions (5.5) ]
• Pulmonary injury [ see Warnings and Precautions (5.6) ]
• Thyroid injury [ see Warnings and Precautions (5.8) ]
• Hypersensitivity [ see Warnings and Precautions (5.10) ]
• The most common adverse reactions (1-2%) leading to discontinuation of intravenous amiodarone therapy are hypotension, asystole/cardiac arrest/pulseless electrical activity, VT, and cardiogenic shock. (6)
• Other important adverse reactions are torsade de pointes, congestive heart failure, and liver function test abnormalities. (6) To report SUSPECTED ADVERSE REACTIONS, contact Baxter Healthcare at 1-866-888-2472 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a total of 1836 patients in controlled and uncontrolled clinical trials, 14% of patients received intravenous amiodarone for at least one week, 5% received it for at least 2 weeks, 2% received it for at least 3 weeks, and 1% received it for more than 3 weeks. The mean duration of therapy in these studies was 5.6 days; median exposure was 3.7 days. The most important adverse reactions were hypotension, asystole/cardiac arrest/pulseless electrical activity (PEA), cardiogenic shock, congestive heart failure, bradycardia, liver function test abnormalities, VT, and AV block. Overall, treatment was discontinued for about 9% of the patients because of adverse reactions. The most common adverse reactions leading to discontinuation of intravenous amiodarone therapy were hypotension (1.6%), asystole/cardiac arrest/PEA (1.2%), VT (1.1%), and cardiogenic shock (1%). Other adverse reactions reported in less than 2% of patients receiving intravenous amiodarone in controlled and uncontrolled studies included the following: abnormal kidney function, diarrhea, shock, sinus bradycardia, Stevens-Johnson syndrome, VF, and vomiting.

6.2 Post-Marketing Experience The following adverse reactions have been reported in the post-marketing experience during or in close temporal relationship to intravenous amiodarone administration. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Blood and Lymphatic System Disorders: pancytopenia, neutropenia, hemolytic anemia, aplastic anemia, thrombocytopenia, and granulocytosis. Cardiac Disorders: sinus node dysfunction (sinus arrest, sinoatrial block), intraventricular conduction disorders including bundle branch block and infra-HIS block, bradycardia (sometimes fatal), ventricular extrasystoles, and antegrade conduction via an accessory pathway. Endocrine Disorders: syndrome of inappropriate antidiuretic hormone secretion (SIADH). Eye Disorders: visual field defect and blurred vision. Gastrointestinal Disorders: pancreatitis. General Disorders and Administration Site Conditions: infusion site reactions, including thombosis, phlebitis, thrombophlebitis, cellulitis, pain, induration, edema, inflammation, urticaria, pruritus, erythema, pigment changes, hypoesthesia, skin sloughing, extravasation possibly leading to venous/infusion site necrosis, and granuloma. Hepatobiliary Disorders: cholestasis, cirrhosis, jaundice, alkaline phosphatase and blood lactate dehydrogenase increase. Musculoskeletal and Connective Tissue Disorders: myopathy, muscle weakness, rhabdomyolysis, muscle spasms, and back pain. Neoplasms benign, malignant and unspecified (incl cysts and polyps) Disorders: thyroid nodules/thyroid cancer. Nervous System Disorders: intracranial pressure increased, pseudotumor cerebri, tremor, dizziness and hypoesthesia. Psychiatric Disorders: confusional state, hallucination, disorientation, and delirium. Renal and Urinary Disorders: acute renal failure (sometimes fatal), renal impairment, renal insufficiency, and blood creatinine increased. Reproductive Disorders and Breast Disorders: Epididymitis Respiratory, Thoracic and Mediastinal Disorders: interstitial pneumonitis, bronchiolitis obliterans organizing pneumonia (possibly fatal), pulmonary alveolar hemorrhage, pulmonary phospholipidoisis, pleural effusion, bronchospasm, dyspnea, cough, hemoptysis, wheezing, and hypoxia. Skin and Subcutaneous Tissue Disorders: toxic epidermal necrolysis (sometimes fatal), Stevens-Johnson syndrome, exfoliative dermatitis, erythema multiforme, skin cancer, pruritus, angioedema, and urticaria. Vascular Disorders: vasculitis and flushing.

Drug interactions with amiodarone are described in Table 5 below. Table 5: Amiodarone Drug Interactions Concomitant Drug Class/Name Examples Clinical Comment QT Prolonging Drugs class I and III antiarrhythmics, lithium, certain phenothiazines, tricyclic antidepressants, certain fluoroquinolone and macrolide antibiotics, azole antifungals, halogenated inhalation anesthetic agents Increased risk of Torsade de Pointes. Avoid concomitant use. Negative Chronotropes digoxin, beta blockers, verapamil, diltiazem, clonidine, ivabradine Potentiates the electrophysiologic and hemodynamic effects of amiodarone, resulting in bradycardia, sinus arrest and AV block. Monitor heart rate. CYP450 Inhibitors Grapefruit juice, certain fluoroquinolone and macrolide antibiotics, azole antifungals, cimetidine Increased exposure of amiodarone. Avoid concomitant use. CYP450 Inducers St. John’s Wort Reduced amiodarone serum levels Cyclosporine Increased plasma levels of cyclosporine have been reported resulting in elevated creatinine, despite reduction of cyclosporine dose. Monitor cyclosporine drug levels and renal function with concomitant use. Cholestyramine Reduced amiodarone serum levels Antiarrhythmics quinidine, procainamide, flecainide Reserve concomitant use for patients who are unresponsive to a single agent. Antiarrhythmic metabolism inhibited by amiodarone. Initiate antiarrhythmic at a lower than usual dose and monitor patient carefully. Reduce dose levels of previously administered antiarrhythmic by 30 to 50% for several days after transitioning to oral amiodarone. Evaluate continued need for antiarrhythmic. Digoxin Increased digoxin concentration. Reduce digoxin by half or discontinue. If continued, monitor for evidence of toxicity. HMG-CoA Reductase Inhibitors simvastatin, lovastatin, atorvastatin Increased plasma concentration of HMG-CoA reductase inhibitor. Limit the dose of lovastatin to 40 mg. Limit the coadministered dose of simvastatin to 20 mg. Lower starting dose of other CYP3A4 substrates may be required. Warfarin Potentiates anticoagulant response and can result in serious or fatal bleeding. Coadministration increases INR by 100% after 3 to 4 days. Reduce warfarin dose by one-third to one-half and monitor INR. Phenytoin Increased steady state levels of phenytoin. Monitor phenytoin levels. Hepatitis C direct acting antiviral Sofosbuvir Cases of symptomatic bradyarrhythmia requiring pacemaker insertion have been reported in patients on oral maintenance amiodarone who initiated therapy with Sofosbuvir.

• Amiodarone is a substrate for CYP3A and CYP2C8, so inhibitors and inducers affect amiodarone exposure ( 7 )
• Amiodarone inhibits p-glycoprotein and CYP1A2, CYP2C9, CYP2D6, and CYP3A, increasing exposure to other drugs ( 7 )

• Pregnancy: Use NEXTERONE during pregnancy only if the potential benefit to the mother justifies the risk to the fetus (8.1) .
• Nursing mothers: Advise mothers to discontinue breast feeding (8.2) .

8.1 Pregnancy Risk Summary Available data from postmarketing reports and published case series indicate that amiodarone use in pregnant women may increase the risk for fetal adverse effects including neonatal hypo- and hyperthyroidism, neonatal bradycardia, neurodevelopmental abnormalities, preterm birth and fetal growth restriction. Amiodarone and its metabolite, desethylamiodarone (DEA), cross the placenta. Untreated underlying arrhythmias, including ventricular arrhythmias, during pregnancy pose a risk to the mother and fetus (see Clinical Considerations). In animal studies, administration of amiodarone to rabbits, rats, and mice during organogenesis resulted in embryo-fetal toxicity at doses less than the maximum recommended human maintenance dose (see Data) . Advise pregnant women of the potential risk to a fetus. The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss or other adverse outcomes. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2%-4% and 15%‑20%, respectively. Clinical Considerations Disease-associated maternal and or embryo/fetal Risk The incidence of ventricular tachycardia is increased and may be more symptomatic during pregnancy. Ventricular arrhythmias most often occur in pregnant women with underlying cardiomyopathy, congenital heart disease, valvular heart disease, or mitral valve prolapse. Most tachycardia episodes are initiated by ectopic beats and the occurrence of arrhythmia episodes may therefore, increase during pregnancy due to the increased propensity to ectopic activity. Breakthrough arrhythmias may also occur during pregnancy, as therapeutic treatment levels may be difficult to maintain due to the increased volume of distribution and increased drug metabolism inherent in the pregnant state. Fetal/Neonatal adverse reactions Amiodarone and its metabolite have been shown to cross the placenta. Adverse fetal effects associated with maternal amiodarone use during pregnancy may include neonatal bradycardia, QT prolongation, and periodic ventricular extrasystoles, neonatal hypothyroidism (with or without goiter) detected antenatally or in the newborn and reported even after a few days of exposure, neonatal hyperthyroxinemia, neurodevelopmental abnormalities independent of thyroid function, including speech delay and difficulties with written language and arithmetic, delayed motor development, and ataxia, jerk nystagmus with synchronous head titubation, fetal growth restriction, and premature birth. Monitor the newborn for signs and symptoms of thyroid disorder and cardiac arrhythmias. Labor and Delivery Risk of arrhythmias may increase during labor and delivery. Data Animal Data In pregnant rats and rabbits during the period of organogenesis, an amiodarone HCl dose of 25 mg/kg/day (approximately 0.4 and 0.9 times, respectively, the maximum recommended human maintenance dose*) had no adverse effects on the fetus. In the rabbit, 75 mg/kg/day (approximately 2.7 times the maximum recommended human maintenance dose*) caused abortions in greater than 90% of the animals. In the rat, doses of 50 mg/kg/day or more were associated with slight displacement of the testes and an increased incidence of incomplete ossification of some skull and digital bones; at 100 mg/kg/day or more, fetal body weights were reduced; at 200 mg/kg/day, there was an increased incidence of fetal resorption (approximately 0.8, 1.6 and 3.2 times the maximum recommended human maintenance dose*). Adverse effects on fetal growth and survival also were noted in one of two strains of mice at a dose of 5 mg/kg/day (approximately 0.04 times the maximum recommended human maintenance dose*). *600 mg in a 60 kg patient (doses compared on a body surface area basis)

8.2 Lactation Risk Summary Amiodarone and one of its major metabolites, DEA, are present in breastmilk at between 3.5% and 45% of the maternal weight-adjusted dosage of amiodarone. There are cases of hypothyroidism and bradycardia in breastfed infants, although it is unclear if these effects are due to amiodarone exposure in breastmilk. Breastfeeding is not recommended during treatment with NEXTERONE [ see Warnings and Precautions (5.6, 5.7) ].

8.3 Females and Males of Reproductive Potential Infertility Based on animal fertility studies, NEXTERONE may reduce female and male fertility. It is not known if this effect is reversible. [ see Nonclinical Toxicology (13.1) ].

8.4 Pediatric Use The safety and effectiveness of amiodarone in pediatric patients have not been established. In a pediatric trial of 61 patients, aged 30 days to 15 years, hypotension (36%), bradycardia (20%), and AV block (15%) were common dose-related adverse reactions and were severe or life-threatening in some cases. Injection site reactions were seen in 5 (25%) of the 20 patients receiving intravenous amiodarone through a peripheral vein irrespective of dose regimen.

8.5 Geriatric Use Clinical studies of amiodarone did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. Carefully consider dose selection in an elderly patient. In general, start at the low end of the dosing range in the elderly to reflect the greater frequency of decreased hepatic, renal, or cardiac function, and concomitant disease or other drug therapy.

Amiodarone is considered a class III antiarrhythmic drug, but it possesses electrophysiologic characteristics of all four Vaughan Williams classes. Like class I drugs, amiodarone blocks sodium channels at rapid pacing frequencies, and like class II drugs, amiodarone exerts a noncompetitive antisympathetic action. One of its main effects, with prolonged administration, is to lengthen the cardiac action potential, a class III effect. The negative chronotropic effect of amiodarone in nodal tissues is similar to the effect of class IV drugs. In addition to blocking sodium channels, amiodarone blocks myocardial potassium channels, which contributes to slowing of conduction and prolongation of refractoriness. The antisympathetic action and the block of calcium and potassium channels are responsible for the negative dromotropic effects on the sinus node and for the slowing of conduction and prolongation of refractoriness in the atrioventricular (AV) node. Its vasodilatory action can decrease cardiac workload and consequently myocardial oxygen consumption. Intravenous amiodarone administration prolongs intranodal conduction (Atrial-His, AH) and refractoriness of the atrioventricular node (ERP AVN) but has little or no effect on sinus cycle length (SCL), refractoriness of the right atrium and right ventricle (ERP RA and ERP RV), repolarization (QTc), intraventricular conduction (QRS), and infra-nodal conduction (His-ventricular, HV). A comparison of the electrophysiologic effects of intravenous amiodarone and oral amiodarone is shown in the table below. Table 5: EFFECTS OF INTRAVENOUS AND ORAL AMIODARONE ON ELECTROPHYSIOLOGIC PARAMETERS Formulation SCL QRS QTc AH HV ERP RA ERP RV ERP AVN Intravenous ↔ ↔ ↔ ↑ ↔ ↔ ↔ ↑ Oral ↑ ↔ ↑ ↑ ↔ ↑ ↑ ↑ ↔No change At higher doses (>10 mg/kg) of intravenous amiodarone, prolongation of the ERP RV and modest prolongation of the QRS have been seen. These differences between oral and IV administration suggest that the initial acute effects of intravenous amiodarone may be predominately focused on the AV node, causing an intranodal conduction delay and increased nodal refractoriness due to slow channel blockade (class IV activity) and noncompetitive adrenergic antagonism (class II activity).