Nexterone (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 also can be used to treat patients with VT/VF for whom oral amiodarone is indicated, but who are unable to take oral medication. During or after treatment with NEXTERONE, patients may be transferred to oral amiodarone therapy [see Dosage and Administration ( 2 )]. Use NEXTERONE for acute treatment until the patient's ventricular arrhythmias are stabilized. Most patients will require this therapy for 48 to 96 hours, but NEXTERONE may be safely administered for longer periods if necessary.

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

NEXTERONE is contraindicated in patients with:

• Known hypersensitivity to any of the components of NEXTERONE Premixed Injection, including iodine. Hypersensitivity reactions may involve rash, angioedema, cutaneous/mucosal hemorrhage (bleeding), fever, arthralgias (joint pains), eosinophilia (abnormal blood counts), uritcaria (hives), thrombotic thrombocytopenic purpura, or severe periarteritis (inflammation around blood vessels).
• Cardiogenic shock.
• Marked sinus bradycardia.
• Second- or third-degree atrio-ventricular (AV) block unless a functioning pacemaker is available.

NEXTERONE should be administered only by physicians who are experienced in the treatment of life-threatening arrhythmias, who are thoroughly familiar with the risks and benefits of amiodarone therapy, and who have access to facilities adequate for monitoring the effectiveness and side effects of treatment. Because of the long half-life of amiodarone and its metabolite desethylamiodarone, the potential for adverse reactions or interactions, as well as observed adverse effects, can persist following amiodarone withdrawal.

5.1 Hypotension Hypotension is the most common adverse reaction seen with intravenous amiodarone. In clinical trials, treatment-emergent, drug-related hypotension was reported as an adverse effect in 288 (16%) of 1836 patients treated with intravenous amiodarone. Clinically significant hypotension during infusions was seen most often in the first several hours of treatment and was not dose related, but appeared to be related to the rate of infusion. 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 )]. In some cases, hypotension may be refractory and result in a fatal outcome [see Adverse Reactions ( 6- 6.2)].

5.2 Bradycardia and Atrio-ventricular Block In 90 (4.9%) of 1836 patients in clinical trials, drug-related bradycardia that was not dose-related occurred while they were receiving intravenous amiodarone for life-threatening VT/VF. Treat bradycardia by slowing the infusion rate or discontinuing NEXTERONE. In some patients, inserting a pacemaker is required. Despite such measures, bradycardia was progressive and terminal in 1 patient during the controlled trials. Treat patients with a known predisposition to bradycardia or AV block with NEXTERONE in a setting where a temporary pacemaker is available.

5.3 Hepatic Injury Elevations of blood hepatic enzyme values [alanine aminotransferase (ALT), aspartate aminotransferase (AST), and gamma-glutamyl transferase (GGT)] are commonly seen in patients with immediately life-threatening VT/VF. Interpreting elevated AST activity can be difficult because the values may be elevated in patients who have had recent myocardial infarction, congestive heart failure, or multiple electrical defibrillations. Approximately 54% of patients receiving intravenous amiodarone in clinical studies had baseline liver enzyme elevations, and 13% had clinically significant elevations. In 81% of patients with both baseline and on-therapy data available, the liver enzyme elevations either improved during therapy or remained at baseline levels. Baseline abnormalities in hepatic enzymes are not a contraindication to treatment. Elevated bilirubin levels have been reported in patients administered intravenous amiodarone. Acute, centrolobular confluent hepatocellular necrosis leading to hepatic coma, acute renal failure, and death has been associated with the administration of intravenous amiodarone [see Dosage and Administration ( 2 )]. In patients with life-threatening arrhythmias, the potential risk of hepatic injury should be weighed against the potential benefit of NEXTERONE therapy. Carefully monitor patients receiving NEXTERONE for evidence of progressive hepatic injury. In such cases, consider reducing the rate of administration or withdrawing NEXTERONE.

5.4 Proarrhythmia Like all antiarrhythmic agents, NEXTERONE may cause a worsening of existing arrhythmias or precipitate a new arrhythmia, sometimes leading to fatal outcomes [see Adverse Reactions ( 6- 6.2)]. Proarrhythmia, primarily torsade de pointes (TdP), has been associated with prolongation, by intravenous amiodarone, of the QTc interval to 500 ms or greater. 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. Amiodarone causes thyroid dysfunction in some patients, which may lead to potentially fatal breakthrough or exacerbated arrhythmias.

5.5 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, bronchospasm, wheezing, fever, dyspnea, cough, hemoptysis, and hypoxia. Some cases have progressed to respiratory failure or death. ARDS Two percent (2%) of patients were reported to have adult respiratory distress syndrome (ARDS) during clinical studies involving 48 hours of therapy. Pulmonary Fibrosis There have been reports of early development of pulmonary fibrosis (within 1 to 3 months) following initiation of amiodarone treatment. Only 1 of more than 1000 patients treated with intravenous amiodarone in clinical studies developed pulmonary fibrosis. In that patient, the condition was diagnosed 3 months after treatment with intravenous amiodarone, during which time the patient received oral amiodarone. Pulmonary toxicity is a well-recognized complication of long-term amiodarone use (see package insert for oral amiodarone).

5.6 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. A causal relationship to the drug has not been clearly established. 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. Perform regular ophthalmic examination, including fundoscopy and slit-lamp examination, during administration of NEXTERONE.

5.7 Thyroid Abnormalities Amiodarone inhibits peripheral conversion of thyroxine (T4) to triiodothyronine (T3) and may cause increased T4 levels, decreased T3 levels, and increased levels of inactive reverse T3 (rT3) in clinically euthyroid patients. Amiodarone is also a potential source of large amounts of inorganic iodine and can cause either hypothyroidism or hyperthyroidism. Evaluate 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. Because of the slow elimination of amiodarone and its metabolites, high plasma iodide levels, altered thyroid function, and abnormal thyroid-function tests may persist for several weeks or even months following NEXTERONE withdrawal. There have been postmarketing reports of thyroid nodules/thyroid cancer in patients treated with amiodarone. In some instances hyperthyroidism was also present. Hyperthyroidism and Thyrotoxicosis Amiodarone causes hyperthyroidism in about 2% of patients. […]

The following adverse reactions are described in Warnings and Precautions: hypotension, rhythm disturbances, hepatic injury, pulmonary injury, thyroid injury, hypersensitivity.

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, without an increased incidence of severe adverse reactions. 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%). Table 4 lists the most common (incidence ≥2%) adverse reactions during intravenous amiodarone therapy considered at least possibly drug-related. These data were collected in clinical trials involving 1836 patients with life-threatening VT/VF. Data from all assigned treatment groups are pooled because none of the adverse reactions appeared to be dose-related. Other adverse reactions reported in less than 2% of patients receiving intravenous amiodarone in controlled and uncontrolled studies included the following: abnormal kidney function, atrial fibrillation, diarrhea, increased ALT, increased AST, lung edema, nodal arrhythmia, prolonged QT interval, atrioventricular block, respiratory disorder, shock, sinus bradycardia, Stevens-Johnson syndrome, thrombocytopenia, 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, intravascular amiodarone deposition/mass (developed in the superior vena cava around acentral venous catheter after long – term [28 days] amiodarone therapy administered through a central line), 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. ADVERSE

7.1 Pharmacodynamic Interactions Drugs prolonging the QT interval: Co-administration of drugs prolonging the QT interval (such as class I and III antiarrhythmics, lithium, certain phenothiazines, tricyclic antidepressants, certain fluoroquinolone and macrolide antibiotics, azole antifungals, halogenated inhalation anesthetic agents) increases the risk of Torsade de Pointes. In general, avoid concomitant use of drugs that prolong the QT interval [see Warnings and Precautions ( 5- 5.4)]. Drugs that slow heart rate: Concomitant use of drugs with depressant effects on the sinus and AV node (e.g., digoxin, beta blockers, verapamil, diltiazem, ivabradine, clonidine) can potentiate the electrophysiologic and hemodynamic effects of amiodarone, resulting in bradycardia, sinus arrest, and AV block. Monitor heart rate in patients on amiodarone and concomitant drugs that slow heart rate.

7.2 Pharmacokinetic Interactions Effect of other drugs on amiodarone Amiodarone is metabolized to the active metabolite desethylamiodarone (DEA) by the cytochrome P450 (CYP450) enzyme group, specifically CYP3A and CYP2C8. Amiodarone has the potential for interactions with drugs or substances that may be substrates, inhibitors or inducers of CYP450 enzymes (e.g., inhibitors such as protease inhibitors, grapefruit juice, certain fluoroquinolone and macrolide antibiotics, azole antifungals and inducers such as St. John’s Wort) or P-glycoprotein. In view of the long and variable half-life of amiodarone, potential for drug interactions exists not only with concomitant medication but also with drugs administered after discontinuation of amiodarone [see Clinical Pharmacology ( 12- 12.3)]. Patients should avoid grapefruit juice beverages while taking amiodarone because exposure to amiodarone is significantly increased [see Clinical Pharmacology ( 12- 12.3)]. Effect of amiodarone on other drugs Amiodarone and DEA are inhibitors of P-glycoprotein and certain CYP450 enzymes, including CYP1A2, CYP2C9, CYP2D6 and CYP3A [see Clinical Pharmacology ( 12- 12.3)]. Antiarrhythmics: The metabolism of quinidine, procainamide, flecainide can be inhibited by amiodarone. In general, initiate any added antiarrhythmic drug at a lower than usual dose and monitor the patient carefully. During transfer to oral amiodarone, reduce the dose levels of previously administered agents by 30 to 50% several days after the addition of oral amiodarone. Review the continued need for the other antiarrhythmic agent after the effects of amiodarone have been established, and attempt discontinuation [see Clinical Pharmacology ( 12- 12.3)]. Digoxin: In patients receiving digoxin therapy, administration of oral amiodarone results in an increase in serum digoxin concentration. Reduce dose of digoxin by half or discontinue digoxin. If digitalis treatment is continued, monitor serum levels closely and observe patients for clinical evidence of toxicity [see Clinical Pharmacology ( 12- 12.3)]. HMG-CoA Reductase Inhibitors: Limit the dose of simvastatin in patients on amiodarone to 20 mg daily. Limit the daily dose of lovastatin to 40 mg. Lower starting and maintenance doses of other CYP3A4 substrates (e.g., atorvastatin) may be required as amiodarone may increase the plasma concentration of these drugs. Anticoagulants: Potentiation of warfarin-type (CYP2C9 and CYP3A substrate) anticoagulant response is almost always seen in patients receiving amiodarone and can result in serious or fatal bleeding. Since the concomitant administration of warfarin with amiodarone increases the INR by 100% after 3 to 4 days, reduce the dose of the anticoagulant by one-third to one-half, and monitor INR closely. Cyclosporine (CYP3A substrate) administered in combination with oral amiodarone has been reported to produce persistently elevated plasma concentrations of cyclosporine resulting in elevated creatinine, despite reduction in dose of cyclosporine. Monitor cyclosporine drug levels and renal function in patients taking both drugs. Increased steady-state levels of phenytoin during concomitant therapy with amiodarone have been reported. Monitor phenytoin levels in patients taking both drugs.

7.3 Serious Symptomatic Bradycardia When Co-administered with Ledipasvir/Sofosbuvir or with Sofosbuvir with Simeprevir Postmarketing cases of symptomatic bradycardia, some requiring pacemaker insertion and at least one fatal, have been reported when ledipasvir/sofosbuvir or sofosbuvir with simeprevir were initiated in patients on amiodarone. Bradycardia generally occurred within hours to days, but in some cases up to 2 weeks after initiating antiviral treatment. Bradycardia generally resolved after discontinuation of antiviral treatment. The mechanism for this effect is unknown. Monitor heart rate in patients taking or recently discontinuing amiodarone when starting antiviral treatment.

8.1 Pregnancy Pregnancy Category D [see Warnings and Precautions ( 5- 5.8)]. Teratogenic Effects Amiodarone and desethylamiodarone cross the placenta. Reported risks 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 retardation
• premature birth Amiodarone has caused a variety of adverse effects in animals. Amiodarone was given intravenously to rabbits at dosages of 5, 10, or 25 mg/kg per day (about 0.1, 0.3, and 0.7 times human intravenous maintenance dose of 0.5 mg/min on a body surface area basis), during gestation days 8 to 16 (organogenesis). The incidence of maternal deaths increased with increasing dose and occurred in all treated groups and controls. Mean fetal weights were significantly decreased in the low and middle dose groups and embryotoxicity (as manifested by fewer full-term fetuses and increased resorptions) occurred at dosages of 10 mg/kg and above. There were no significant differences in the number of minor fetal abnormalities and no major fetal abnormalities were observed. Amiodarone was administered by continuous intravenous infusion to rats at dosages of 25, 50, or 100 mg/kg per day (about 0.3, 0.7 and 1.3 times the human intravenous maintenance dose of 0.5 mg/min on a body surface area basis) during gestation days 8 to 16 (organogenesis). Maternal toxicity (manifest as reduced weight gain and food consumption) and embryotoxicity (manifest as increased resorptions, decreased live litter size and fetal body weights, and delayed sternal and metacarpal ossification) were observed in the 100 mg/kg group. The delayed ossification was reversible and related to decreased fetal weight. Fetal thyroid tissues appeared normal in all groups. Nonteratogenic Effects Very high concentrations of amiodarone and desethylamiodarone may be found in testes. An elevated follicle-stimulating hormone and luteinizing hormone levels, suggestive of testicular dysfunction, have been reported in men on long-term amiodarone treatment. While planning pregnancy after discontinuation of amiodarone treatment, consider the long half-life of amiodarone and its metabolite DEA.

8.2 Labor and Delivery It is not known whether the use of amiodarone during labor or delivery has any immediate or delayed adverse effects. Preclinical studies in rodents have not shown any effect on the duration of gestation or on parturition.

8.3 Nursing Mothers Amiodarone and one of its major metabolites, desethylamiodarone (DEA), are excreted in human milk, suggesting that breast-feeding could expose the nursing infant to a significant dose of the drug. Nursing offspring of lactating rats administered amiodarone have demonstrated reduced viability and transient reduced body weight gains. The risk of exposing the infant to amiodarone and DEA must be weighed against the potential benefit of arrhythmia suppression in the mother. Advise the mother to discontinue nursing.

8.4 Pediatric Use The safety and effectiveness of amiodarone in pediatric patients have not been established; therefore, the use of amiodarone in pediatric patients is not recommended. 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.