Dronedarone Vs Amiodarone (Multaq Vs Amiodarone)

“Dronedarone Vs Amiodarone” compares two drugs commonly used to maintain normal sinus rhythm in patients with atrial fibrillation.

Atrial fibrillation is when electrical impulses bombard the AV node and the ventricles simultaneously resulting in rapid and irregular heart contractions.

Normally, one impulse travels via the AV node to the ventricles and this is followed by a cardiac contraction. However, in atrial fibrillation, multiple impulses travel at irregular intervals and so the ventricles contract rapidly and irregularly.

Various drugs are used to control the heart rate. These include:

• Beta-blockers
• Calcium channel blockers, and
• Digoxin

Anti-arrhythmic drugs are used to convert the rhythm into a normal sinus rhythm. These include:

• Quinidine
• Procainamide
• Flecainide
• Sotalol
• Amiodarone
• Dronedarone.

Here is a table summarizing the drugs used to treat atrial fibrillation:

Action	Drug Class	Examples of Drugs
Control heart rate	Beta-blockers	Metoprolol, Propranolol, Atenolol
	Calcium channel blockers	Diltiazem, Verapamil
	Digoxin	Digoxin
Convert into sinus rhythm	Class Ia antiarrhythmics	Quinidine, Procainamide
	Class Ic antiarrhythmics	Flecainide, Propafenone
	Class III antiarrhythmics	Amiodarone, Dronedarone, Sotalol

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Dronedarone (Multaq) Vs Amiodarone: Comparing the Pharmacokinetics:

To understand the difference between Dronedarone and Amiodarone, it is important to understand their pharmacokinetics.

A few important differences between Dronedarone Vs Amiodarone are:

• Dronedarone has a short half-life and so a shorter duration of action
• Dronedarone has an easy dosing schedule compared to Amiodarone
• Monitoring for thyroid function is not required when using Dronedarone Vs Amiodarone as Dronedarone (Multaq) does not contain iodine.

Other pharmacokinetic differences are highlighted in the table below:

Pharmacokinetics	Dronedarone (Multaq)	Amiodarone
Absorption	Rapid and extensive	Slow and variable
Bioavailability	Approximately 15%	Approximately 50%
Time to peak concentration	4-6 hours	3-7 hours
Distribution	High volume of distribution and extensively bound to plasma proteins	High volume of distribution and extensively bound to plasma proteins
Metabolism	Extensively metabolized in the liver by CYP3A4 and CYP2D6. Forms active and inactive metabolites	Extensively metabolized in the liver by CYP3A4 and CYP2C8. Forms active and inactive metabolites
Half-life	Approximately 13-19 hours	Long half-life of 20-47 days, with a terminal half-life of 61 days for amiodarone and up to 150 days for its major metabolite, desethylamiodarone
Excretion	Primarily fecal (81% of dose)	Primarily fecal (40-50% of dose) and urinary (10-15% of dose)
Dosing and Administration	Typically administered twice daily with food. Adjustments needed in patients with hepatic or renal impairment	Typically administered once or twice daily. Adjustments needed in patients with hepatic or renal impairment
Drug Interactions	Substrate and inhibitor of CYP3A4 and P-gp. Potential for significant drug interactions	Substrate and inhibitor of CYP3A4, CYP2C8, and P-gp. Potential for significant drug interactions
Special Considerations	Contraindicated in patients with severe liver or lung disease. Requires monitoring of liver and lung function. Potential for QT prolongation and proarrhythmic effects	Requires monitoring of liver and thyroid function due to the potential for thyroid abnormalities. Potential for QT prolongation and proarrhythmic effects

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Pros and Cons of Dronedarone Vs Amiodarone:

Both Dronedarone and amiodarone are considered to be equally effective. However, in patients with advanced decompensated heart failure, Amiodarone is considered to be a safer choice because of an increased risk of death from Dronderaone.

Contrary to patients with advanced structural heart disease, Dronedarone is more effective in maintaining sinus rhythm in patients with atrial fibrillation.

In addition, Dronedarone is much safer with fewer drug interactions and does not require monitoring of thyroid functions compared to Amiodarone.

The table below summarized the Pros and Cons of Dronedarone Vs Amiodarone:

	Dronedarone	Amiodarone
Side effects	Few	More
Dosing Schedule	Simple but frequent	Complicated but less frequent
Drug Interactions	Few	More
Efficacy	Less potent	More potent
Use in severe heart failure	Not recommended	May be used
Formulations	Oral	Oral and Intravenous
Monitoring	Does not require monitoring of thyroid functions	Thyroid functions need to be monitored
Potential for toxicity	Low because of short half-life	High because of the long half-life

The table above shows that although Dronedarone is considered less effective than amiodarone, it is safe, has fewer drug interactions, fewer side effects, easy dosing schedule, and does not interfere with the functioning of the thyroid gland.

These Pros and Cons are summarized in the table below:

	Dronedarone	Amiodarone
PROS	Fewer side effects compared to amiodarone Simpler dosing regimen Lower risk of drug interactions Potential reduced risk of hospitalization for cardiovascular events in certain populations	Established efficacy and safety profile Can be effective in certain difficult-to-treat cases Available in multiple formulations (oral and intravenous) Long half-life allows for less frequent dosing
CONS	Less potent antiarrhythmic effects compared to amiodarone May not be as effective in certain cases Contraindicated or cautioned in certain patient populations Not recommended for patients with severe heart failure May require dose adjustments in patients with liver or kidney impairment	More side effects compared to dronedarone Long half-life may result in accumulation in organs and potential toxicity Higher risk of drug interactions Requires a loading phase and maintenance phase dosing regimen Requires regular monitoring of thyroid and lung function May not be suitable for all patients due to potential organ toxicity

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Is Dronedarone really safe compared to Amiodarone?

Based on the information presented earlier, the pharmacokinetic parameters indicate that Dronedarone may be safer than Amiodarone.

However, the true safety of these drugs can be determined through clinical trials involving human subjects.

In a published study, the author summarized the following findings [Ref]:

Outcome	Dronedarone	Amiodarone
Recurrence of AF (per 1,000 patients treated)	Approximately 228 more recurrences compared to Amiodarone
Adverse events requiring discontinuation of the drug (per 1,000 patients treated)	62 fewer adverse events compared to Amiodarone
All-cause mortality	No statistically significant difference compared to Amiodarone
Incidence of thyroid toxicity (percentage)	Comparable between Dronedarone and Placebo: 4% vs. 3%	More with Amiodarone than Placebo: 7.5% vs. 0%
Incidence of symptomatic bradyarrhythmias	Comparable between Dronedarone and Placebo: 2.8% vs. 1.1%	More with Amiodarone than Placebo: 3.7% vs. 0%
Incidence of hepatotoxicity	Comparable between Dronedarone and Placebo: 3.5% vs. 2.5%	More with Amiodarone than Placebo: 0.1% vs. 0%

The table above shows the comparison of the outcomes between Dronedarone and Amiodarone treatments.

For every 1,000 patients treated with Dronedarone instead of Amiodarone, there would be approximately 228 more recurrences of atrial fibrillation (AF), but 62 fewer adverse events requiring discontinuation of the drug.

There was no significant difference in all-cause mortality between the two drugs.

The incidence of thyroid toxicity, symptomatic bradyarrhythmias, and hepatotoxicity were comparable between Dronedarone and placebo, while the incidence of these adverse effects was higher with Amiodarone than with placebo.

In addition, the FDA has issued a serious warning, known as a “Black Box Warning,” for the use of MULTAQ in certain situations. These include [Ref]:

• Patients with NYHA Class IV heart failure, where the risk of death doubles.
• Patients with symptomatic heart failure who have recently been hospitalized for heart failure, where the risk of death doubles.
• Patients with permanent atrial fibrillation who are unable to convert to normal sinus rhythm, where the risk of stroke, hospitalization, and death doubles.

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Efficacy of Dronedarone Vs Amiodarone:

Dronedarone is less effective than amiodarone, especially in patients with structural heart disease and heart failure.

In atrial fibrillation, it is equally effective as amiodarone and other anti-arrhythmic drugs. It has been shown to lower the risk of death and hospitalizations in patients with atrial flutter and atrial fibrillation.

Additionally, dronedarone may have the benefit of lowering blood pressure and reducing ischemic events. However, its main advantages, which the manufacturer emphasizes, are that:

• it is safer than amiodarone,
• has fewer drug interactions, and
• comes with an easy dosing schedule.

Cost of Dronedarone Vs Amiodarone:

Amiodarone is much cheaper than Dronedarone (Multaq). The average monthly cost of Amiodarone is roughly USD 60$.

Compared to Amiodarone, Dronedarone (Multaq) is about 10 times more expensive. The monthly supply of Dronedarone (Multaq) costs around USD 800$ +/-100$.

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