Overview
11 DESCRIPTION Pacerone (amiodarone hydrochloride tablets, USP) are an antiarrhythmic drug, available for oral administration as 100 mg; peach tablets, 200 mg; pink tablets and 400 mg; white tablets containing amiodarone hydrochloride, USP. All three strengths of Pacerone tablets contain the following inactive ingredients: lactose monohydrate, magnesium stearate, povidone, pregelatinized corn...
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action 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.
Indications
- 1 INDICATIONS AND USAGE Pacerone is 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. Pacerone is an antiarrhythmic indicated for: Recurrent ventricular fibrillation. ( 1 ) Recurrent hemodynamically unstable ventricular tachycardia. ( 1 )
Common Doses
- 1600 mg
- 800 mg
- 400 mg
- 1000 mg
Dosage
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 dose of 800 to 1600 mg/day until initial therapeutic response occurs (usually 1 to 3 weeks).
Black Box Warning
WARNING: PULMONARY, HEPATIC and CARDIAC TOXICITY Pacerone is intended for use only in patients with the indicated life-threatening arrhythmias because its use is accompanied by substantial toxicity [see Indications and Usage (1) ] . Pacerone can cause pulmonary toxicity (hypersensitivity pneumonitis or interstitial/alveolar pneumonitis) that has resulted in clinically manifest disease at rates as high as 17% in some series of patients. Pulmonary toxicity has been fatal about 10% of the time .
Contraindications
- 4 CONTRAINDICATIONS Cardiogenic shock. Sick sinus syndrome, second- or third-degree atrioventricular block, bradycardia leading to syncope without a functioning pacemaker. Known hypersensitivity to the drug or to any of its components, including iodine. Pacerone is contraindicated in patients with ( 4 ): Cardiogenic shock. Sick sinus syndrome, second- or third-degree AV block, bradycardia leading to syncope without a functioning pacemaker. Known hypersensitivity to the drug or any of its components.
Side Effects
- 6 ADVERSE REACTIONS The following serious adverse reactions are described in more detail in other sections of the prescribing information: Pulmonary Toxicity [see Warnings and Precautions (5.2) ] Hepatic Injury [see Warnings and Precautions (5.3) ] Worsened Arrhythmia [see Warnings and Precautions (5.4) ] Visual Impairment and Loss of Vision [see Warnings and Precautions (5.5) ] Thyroid Abnormalities [see Warnings and Precautions (5.6) ] Bradycardia [see Warnings and Precautions (5.7) ] Peripheral Neuropathy [see Warnings and Precautions (5.
Interactions
- 7 DRUG INTERACTIONS Because of amiodarone's long half-life, expect drug interactions to persist for weeks to months after discontinuation of amiodarone. Drug interactions with amiodarone are described in Table 1 below. Table 1: Amiodarone Drug Interactions Concomitant Drug Class/Name Examples Clinical Comment Pharmacodynamic Interactions 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...