Cordarone

Selected form

Amiodarone Hydrochloride

Method of action: Antianginal, Antiarrhythmic, Antispasmodic, Cardiac Therapy, Group Iii, Hypotensive

Treatment option: Ventricular Tachycardia, Wolff-Parkinson-White Syndrome, Tachycardia, Atrial flutter, Ventricular Fibrillation

Medically reviewed

Marina Burgos

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Cordarone

Property	Description
Active Ingredient	Amiodarone Hydrochloride
Form	Tablet (oral) and Solution for Injection (intravenous)
Pharmacological Class	Antiarrhythmic Drug (Class III)
Common Use	Stabilization of severe cardiac rhythm disorders
Origin	Synthetic, iodine-containing benzofuran derivative

1. What is Cordarone and Its Pharmacological Identity?

Cordarone is a potent, prescription-only medicine containing the active component Amiodarone Hydrochloride, an essential Antiarrhythmic drug used for complex, severe, life-threatening cardiac rhythm disorders. The drug is formally classified as a Class III antiarrhythmic agent within the Vaughan Williams classification system. This classification confirms its ability to provide comprehensive electrical stabilization for patients who are unable to be controlled by other antiarrhythmic therapies. Amiodarone is indicated for arrhythmias where other treatments are ineffective or contraindicated.

2. Composition, Origin, and Available Forms

The therapeutic product relies on the single active ingredient Amiodarone Hydrochloride, which is a synthetic compound derived from benzofuran and is chemically distinct due to its substantial iodine content. This iodine-containing structure gives the molecule properties that differentiate it from other antiarrhythmic agents. The medicine is prepared in two primary forms to support varied clinical needs: an oral formulation (tablet) for chronic management and a sterile solution for injection (intravenous) for immediate stabilization during acute critical events. While Cordarone is a well-known brand, other trade names, such as Pacerone, also utilize this identical Amiodarone Hydrochloride formulation.

3. The Principle of Rhythmic Stabilization (High-Level)

The core purpose of Amiodarone Hydrochloride is to restore and sustain a stable heart rhythm through specific electrophysiological effects. Its mechanism involves prolongation of the cardiac action potential, which results in an increased effective refractory period (the duration the heart muscle is electrically insulated). This action promotes robust electrical stabilization to prevent the recurrence of rapid, disorganized signals. Amiodarone is an agent for both ventricular and supraventricular arrhythmias due to its ability to modulate multiple cardiac ion channels. This reinforces the drug's essential capability to establish consistent control over complex cardiac rhythm disorders, such as maintaining a steady rhythm following an episode of sustained ventricular tachycardia.

Regulatory References

What side effects are possible with Cordarone?

Possible Side Effects and Safety Information

The official safety profile for Cordarone (Amiodarone) outlines adverse reactions categorized by frequency and the organ systems affected, as documented by regulatory authorities (e.g., FDA, EMA).

Adverse Reaction Scope

Classification	Examples of Officially Documented Adverse Reactions
Very Common	Corneal microdeposits, photosensitivity (sun sensitivity), gastrointestinal disturbances (e.g., nausea, taste changes).
Common	Hypothyroidism or hyperthyroidism, peripheral neuropathy, acute or chronic liver disorders, pulmonary toxicity (e.g., interstitial pneumonitis), tremor.
Uncommon to Rare	Proarrhythmia (onset or worsening of arrhythmia), severe cardiac conduction disturbances, severe liver failure, and optic neuropathy/neuritis (risk of blindness).

Official Safety Constraints and Patterns

The regulatory profile highlights risks associated with long-term exposure and potential severity. The most serious adverse reactions, including fatal pulmonary toxicity (such as pulmonary fibrosis) and fatal hepatotoxicity, are explicitly documented and typically manifest with extended therapy duration. The drug's safety profile mandates mandatory, routine monitoring of pulmonary function, liver enzymes, and thyroid function due to the potential for these systemic toxicities.

Safety notes also indicate that gastrointestinal effects are often observed at treatment initiation. The high iodine content is an intrinsic characteristic that contributes to the risk of thyroid dysfunction. Safety considerations for older adults include an increased risk of severe bradycardia and conduction disturbances.

Overdose and Emergency Response

Overdose and when to seek help

The official regulatory profile classifies Amiodarone Hydrochloride overdose as potentially severe and life-threatening. Overdose exposure requires patients to seek emergency medical attention immediately, as documented in government prescribing information.

Documented Overdose Manifestations

Domain	Official Regulatory Findings
Cardiovascular Manifestations	Profound sinus bradycardia (slow heartbeat), various degrees of heart block (conduction disturbances), circulatory failure (shock), and the potential for a fatal outcome. Arrhythmias, including Torsades de Pointes (TdP), may worsen or emerge.
Other Manifestations	Nausea, blurred vision, lightheadedness, and fainting have been reported. Hepatic injury is also documented as a potential severe systemic consequence.

Required Emergency Actions

In cases of suspected overdose, general management is strictly symptomatic and supportive. There is no specific antidote known, and regulatory documents state the drug is not removable by dialysis. Due to the severity of potential effects, adequate and prolonged surveillance of the patient, with particular focus on cardiac status and liver function, is required following exposure. Severe bradycardia and conduction disturbances are specifically noted as increased risks in elderly patients.

Therapeutic Uses of Cordarone

Quick Facts

Cordarone is authorized for the supportive management of serious, recurrent ventricular rhythm disturbances that pose a risk to life. Its use is generally reserved for individuals whose condition has not responded to other available therapies or who cannot tolerate alternative agents.

What Cordarone Treats: Main Uses and Benefits

Cordarone (amiodarone) is a prescription medication utilized to help manage and stabilize specific severe heart rhythm abnormalities. It is indicated for use in adult patients who experience documented, recurrent forms of ventricular arrhythmia.

Therapeutic Domains:

Recurrent Ventricular Fibrillation (VF): The medication is indicated for the treatment of VF that has returned despite previous attempts at control.
Recurrent Hemodynamically Unstable Ventricular Tachycardia (VT): Cordarone is used to address VT that is recurrent and causing unstable blood flow in the body.

The primary therapeutic goal is to help maintain a more regular heart rhythm and reduce the frequency of these life-threatening events. Cordarone is part of a therapeutic strategy when a patient's condition is refractory to other established antiarrhythmic agents, or when alternative therapies are not appropriate options.

Eligibility and Restrictions for Use

Cordarone (amiodarone) is reserved exclusively for adult patients with documented, life-threatening ventricular rhythm disorders that have not responded to, or are intolerant of, other antiarrhythmic therapies. Its eligibility profile is highly constrained by several absolute contraindications defined by regulatory bodies.

Populations Strictly Contraindicated

The medicine must not be used in patients with the following pre-existing conditions:

Severe Conduction Defects: Patients experiencing cardiogenic shock, marked sinus bradycardia, sick sinus syndrome, or second- or third-degree AV block without a functioning permanent pacemaker.
Thyroid Issues: Individuals with existing hyperthyroidism or a history of thyroid dysfunction.
Hypersensitivity: Known allergy to amiodarone, iodine, or any component of the drug formulation.

Specific Use Restrictions

Population Group	Regulatory Status
Pediatric Patients (<18 years)	Safety and efficacy have not been established; use is not recommended. The IV form is contraindicated in neonates due to benzyl alcohol content.
Pregnancy	Strongly advised against (FDA Category D); use is conditional on the potential benefit justifying the fetal risk.
Lactation	Contraindicated; nursing mothers must discontinue breastfeeding.
Electrolyte Imbalance	Hypokalemia or hypomagnesemia must be corrected before initiation of treatment.
Hepatic Impairment	Close clinical monitoring is prudent, as clearance may be reduced.

These rules ensure the drug is confined to the specific population where its specialized therapeutic use is warranted despite the defined risks.

What should I know about interactions with other medicines?

Pharmacokinetic Interactions (Exposure Modification)

Cordarone's official interaction profile is primarily governed by its potent ability to inhibit multiple metabolic enzymes (CYP2C9, CYP2D6, CYP3A4) and the P-glycoprotein (P-gp) transporter. This pharmacokinetic interaction reduces the clearance of co-administered medicines that are substrates for these systems, resulting in increased systemic exposure.

Warfarin and Digoxin: Co-administration significantly raises the plasma concentrations of both Warfarin and Digoxin, necessitating required dose adjustments and intensified monitoring for both medicines.
Simvastatin: Due to documented risk from increased exposure, the Simvastatin dose must be restricted to a maximum of 20 mg daily when co-administered.

Pharmacodynamic and Contraindication Restrictions

Interactions based on combined physiological effects are also officially documented by regulatory sources.

Antiarrhythmic Agents: Co-administration with other Class I and Class III antiarrhythmics is generally restricted due to the additive risk of QTc prolongation and proarrhythmia (Torsade de Pointes).
Antivirals: Combination with Sofosbuvir and other Direct Acting Antivirals (DAAs) is advised against because of the documented risk of severe symptomatic bradycardia.
Conduction-Slowing Agents: Co-administration with beta-blockers or non-dihydropyridine calcium channel blockers can result in additive depressant effects on cardiac conduction, such as bradycardia.

Food and Other Substances

Consumption of Grapefruit or Grapefruit juice should be avoided as it is documented to significantly increase amiodarone exposure (AUC and Cmax).
Elderly patients show lower clearance, which affects the potential for drug accumulation and the persistence of drug interactions after discontinuation.

Mechanism of Action

Multi-Channel Ion Current Regulation (Class III Effect)

The primary mechanism involves the non-competitive blockade of multiple cardiac ion channels—chiefly the delayed rectifier potassium currents ( I Kr), alongside effects on sodium ( I Na) and L-type calcium ( I Ca) channels. This multi-channel inhibition significantly prolongs the cardiac action potential duration (APD) and the effective refractory period (ERP) of myocardial tissue. The extended ERP interrupts the electrical feedback loops that perpetuate rapid, disorganized signal conduction, establishing electrical regulation.

Pathway Modulation and Dynamics

The molecule also acts as a non-competitive antagonist of alpha and beta adrenergic receptors, dampening sympathetic influence and reducing cellular excitability, which slows the spontaneous rate of electrical firing and impulse conduction, particularly through the SA and AV nodes. Furthermore, the drug and its active metabolite, Desethylamiodarone (DEA), require extensive tissue accumulation to achieve maximal electrophysiological effects, resulting in a delayed onset but facilitating the long-term maintenance of modulated electrical parameters.

Dosage and Administration Information

Cordarone (amiodarone) administration is governed by a Dual Administration Route System, which utilizes the oral tablet for long-term chronic management and the intravenous solution for injection for immediate intervention during acute clinical episodes. The medicine is typically initiated in a hospital setting where continuous monitoring is available, reflecting the clinical requirement for continuous monitoring during initiation.

The standard oral therapy employs a Multi-Phasic Dosing Regimen that systematically progresses from a high initial loading dose of 800 mg to 1600 mg per day, taken in divided doses. Following this initial period, the dose is reduced to an intermediate level (600 mg to 800 mg/ day) for about one month before settling into the long-term maintenance dose, which is usually 400 mg per day. Oral dosing must adhere to a Consistent Intake Requirement, meaning tablets should be administered consistently with meals.

For intravenous use, the solution must be diluted in 5% Dextrose in Water (D5W), and high concentrations are directed for delivery via a central venous catheter using an infusion pump. Dosage guidelines for pediatric patients are not formally established.

Recent Clinical Evidence

Research Evidence / Overview of Studies for Cordarone

Cordarone (amiodarone) was studied for complex, life-threatening heart rhythm disorders, primarily in patients whose conditions were considered refractory, meaning they had not responded adequately to other treatments. The research base consists primarily of Randomized Controlled Trials (RCTs), large systematic reviews, and long-term observational studies that contribute to understanding patient-reported outcomes.

Evidence for Use in Recurrent Ventricular Fibrillation (VF)

Research for life-threatening VF includes both short-term RCTs for acute emergency use and larger, long-term clinical trials. These studies focused on populations of adults who had experienced documented VF, a condition characterized by acute or disruptive episodes. Studies explored outcomes related to episodic changes, such as the rate of successful arrhythmia termination when the intravenous form was observed. Long-term research monitored the recurrence rate of VF episodes and measured overall survival rates among the observed populations. The evidence remains heterogeneous (variable) across studies, particularly regarding the long-term effect on all-cause mortality.

Long-Term Research and Durability of Response

The evidence base includes analyses where follow-up durations were limited in some acute trials, but also longer-term observational cohort studies that tracked patient status for up to five years or more. These extended studies examined the durability of the rhythm control achieved and tracked major outcomes. It is noted that long-term effects are not fully established and data are still emerging regarding the durability of the effect after treatment is stopped.

Evidence in Special Patient Populations

Research has explored how Cordarone affects various patient groups, particularly those with conditions marked by functional limitations. Evidence suggests that age alone was not reported to limit the drug's use in the studied populations. Studies also examined patient subgroups who had Left Ventricular Dysfunction (LVD) or Congestive Heart Failure (CHF). However, data for the pediatric population remains insufficient, and regulatory documentation indicates that appropriate studies have not been performed to establish safety and efficacy in children under 18 years of age.

Key Studies & References

Amiodarone Pharmacology, Side Effects, and Use - National Institutes of Health (NIH) StatPearls

Frequently Asked Questions (FAQ)

Common questions about Cordarone (FAQ)

Q: Do most patients experience the thyroid side effects of Cordarone?

Official product information indicates that thyroid dysfunction, which includes both an underactive (hypothyroidism) and overactive (hyperthyroidism) state, is a common adverse reaction. Estimates of hypothyroidism incidence generally range from 6% to 32%, while hyperthyroidism is cited less frequently, typically from 1% to 12% in adult populations. Mandatory, routine monitoring of thyroid function is described as necessary throughout therapy.

Q: Is it true that Cordarone can cause blue or gray skin discoloration?

Regulatory documents confirm that a blue-gray or slate-colored skin pigmentation is a possible, though uncommon, side effect of the medicine. This cosmetic change is often associated with the cumulative dose received over time and exposure to sunlight. Official information indicates that the medication can also cause photosensitivity, which is a very common reaction where the skin becomes highly sensitive to the sun.

Q: What common over-the-counter medications are listed as having interactions with Cordarone?

Official documents highlight that Cordarone inhibits certain liver enzymes, which can increase the concentration of other medicines in the body. This interaction extends to active ingredients found in some common over-the-counter (OTC) products. For example, ingredients like diphenhydramine (found in many sleep aids) have a documented potential for serious cardiac effects. Official documents also note that acetaminophen (a pain reliever) has associated liver warnings when combined with this drug.

Q: What evidence exists regarding Cordarone's use in patients with a pacemaker?

Cordarone is strictly contraindicated in patients who have pre-existing severe conduction defects, such as certain types of AV block. The contraindication for severe conduction defects specifically applies to patients who do not have a functioning permanent pacemaker in place. This indicates that its use is addressed when the patient has a device to manage severe conduction problems.

Q: Is fatigue a documented common side effect of Cordarone?

Yes, based on official regulatory data, unusual tiredness, weakness, or fatigue is categorized as a commonly reported adverse reaction. This is generally experienced as a feeling of weariness that occurs more often than expected during the course of treatment.

Q: What are the general expectations about the benefit-risk profile for Cordarone use?

Regulatory agencies have reserved Cordarone for the treatment of documented, life-threatening ventricular arrhythmias that have proven resistant to other therapies. The official boxed warning indicates that its therapeutic use is justified by its effectiveness in these critical heart conditions. This effectiveness is a factor considered against the documented risk of serious, potentially fatal toxicities, including injury to the lungs, liver, and thyroid.

Q: Does Cordarone interact with common anesthesia used for general surgery?

Yes, the official product information includes warnings about the potential for interaction with certain agents used in general surgery, including inhaled anesthetics and specific opioids. These interactions can increase the risk of severe cardiac complications, such as a drop in blood pressure (hypotension) or a critically slow heart rate (bradycardia). Official documentation highlights the importance of the surgical team being aware of Cordarone use prior to any procedure.

Q: What happens in general if a person accidentally misses a single dose of Cordarone?

Regulatory documents emphasize that doses should not be missed due to the potential risk of serious heart rhythm problems. Because the drug accumulates in the body over time, the effects of a single missed dose are complex. The importance of adherence to the prescribed schedule is emphasized. Official information directs patients to follow the specific instructions provided by their healthcare provider if a dose is missed.

Q: What are the common clinical signs that Cordarone is impacting the thyroid gland?

When Cordarone impacts the thyroid, it may present as two different conditions. Signs of an overactive thyroid (hyperthyroidism) can include a new or worsening heart arrhythmia, unexplained weight loss, or heat intolerance. Signs of an underactive thyroid (hypothyroidism) can include weight gain, sluggishness (lethargy), and intolerance to cold.

Q: What does official research evidence indicate about Cordarone's use for atrial fibrillation?

The official FDA approval is restricted to the treatment of life-threatening ventricular arrhythmias that are resistant to other treatments. Official labeling indicates that while its approval is limited, regulatory sources acknowledge its use in clinical practice for other supraventricular tachyarrhythmias, such as atrial fibrillation.

Q: Does taking Cordarone cause an effect on blood pressure?

Yes, the official warnings mention that Cordarone may cause hypotension, which is low blood pressure. This effect is seen most often when the medicine is administered intravenously in a hospital setting. The drug has vasodilatory properties, meaning it causes blood vessels to widen, which can result in a reduction of overall blood pressure.

Q: Is there any information on how Cordarone affects the kidneys?

While the medicine's primary toxicities are focused on the liver, lungs, and thyroid, regulatory documents include information on kidney effects. Rare cases of acute renal (kidney) failure have been documented. These instances were primarily associated with the intravenous form when it was administered at concentrations and rates exceeding the recommended guidelines.

How should Cordarone be stored and disposed of?

Storage and Disposal Requirements

Cordarone (amiodarone) must be stored at controlled room temperature, specifically 25°C (77°F), with permitted excursions between 15 C and 30 C (59 F and 86 F). Both tablets and the injection must be protected from light, heat, and moisture. The tablets should be kept in a tightly closed container.

Child Safety and Handling

The medication must be kept out of the reach of children. The injection is incompatible with saline and must only be diluted with 5% w/v dextrose; unused solution must be discarded immediately.

Disposal

Unused or expired Cordarone must not be disposed of in household waste or wastewater. Disposal should follow local requirements and be managed by a healthcare professional or pharmacist.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.