Amiodarone vs Cardizem vs Multaq: A Detailed Comparison

Arryhthmias are complications of many heart diseases. Problems with heart rhythm can occur due to atherosclerosis, heart failure, or a heart attack. Regardless of the origin, when not treated, arrhythmias can be fatal. In this article, we will take a close look at Amiodarone, Cardizem, and Multaq. All three of these medications are commonly used in the treatment of various heart rhythm disorders. We will review their indications, mechanisms of action, and potential side effects.
Jakub Gwiazdecki

Jakub Gwiazdecki

Fifth year medical student at the Medical Faculty of Comenius University in Bratislava.

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What is Amiodarone?

Amiodarone is a drug used in the treatment of various heart rhythm disorders. It belongs to the class III antiarrhythmic drugs prescribed, especially for ventricular and supraventricular arrhythmias [1, 2]. It is known to be very effective in the treatment of atrial fibrillation [3]. As this medication is an iodinated benzofuran derivative, it contains up to 40% iodine [4].

Amiodarone reduces the sympathetic effect of the autonomic nervous system on the heart. It is also known for its ability to prolong the refractory period in the heart cells. The refractory period is a time during which heart signals cannot excite heart cells [2].

It interacts with other medications, among which are digoxin, warfarin, and class I antiarrhythmic drugs [2].

Indications for Amiodarone

Indications for amiodarone include:

Mechanism of action of Amiodarone

Amiodarone works by inhibiting various types of myocardial potassium channels. The blockage of these channels results in longer refractory periods and, thus, longer breaks between the heartbeats [6].

Thanks to the inhibition and longer resting, non-excitable time, amiodarone limits the spread of unwanted additional electric stimuli, which leads to fibrillation or arrhythmias. The rhythm becomes slower and more regular.

Side effects of Amiodarone

Amiodarone is effective in rhythm stabilization and arrhythmia prevention, but it has its side effects. The most popular side effects are:

  • nausea
  • constipation
  • vomiting
  • fatigue
  • coordination problems
  • sleep disturbance
  • headache
  • stomach pain [7].

The more serious side effects include allergic reactions. They can take various forms, ranging from rashes to hives and swellings of the face and lips.

Also, respiratory problems can occur, including difficulty breathing, coughing, chest pain, or shortness of breath. Amiodaron can also affect vision. It can lead to higher light sensitivity and blurred sight [7].

Some other problems amiodarone can cause are hepatic side effects. They can exhibit tiredness and weakness with changes in the skin color and darkening of the urine.

Even though it is an antiarrhythmic drug, it can also cause chest pain with an irregular heartbeat, and fainting can also occur [7].

Other serious side effects are damage to the nerves and numbness in the extremities [7].

In rare cases, amiodarone can cause acute pancreatitis [8], liver cirrhosis [9], and alveolar hemorrhage [10].

What is Cardizem?

Cardizem is also known as diltiazem and is a prescription for high blood pressure and cardiac chest pain. It belongs to the class of calcium-channel blockers, which make the heart pump the blood with less effort. Less work by the heart means that the cardiac muscle needs less oxygen, which is helpful in situations like ischemic chest pain [1, 2].

Diltiazem is available in two forms: oral tablets or capsules and intravenous ones.

Typically, Cardizem is part of a comprehensive treatment plan that includes lifestyle changes such as diet and exercise [1].

Indications for Cardizem

There are two main indications for Diltiazem treatment:

  • high blood pressure [1],
  • angina pectoris (chest pain due to oxygen in the heart) [4, 11]

Mechanism of Action of Cardizem

Cardizem works by inhibiting the inflow of calcium ions into cardiac and smooth muscle cells during depolarization. Low levels of this ion in the cells of the peripheral and cardiac arteries lead to relaxation and dilation of vessels. An increase in the blood circulation tubes, which is achieved with general artery dilation, lowers the blood pressure and increases the blood perfusion of the heart [12].

In the heart, the blocked calcium channels limit the amount of calcium entering the cardiac muscle cells. Lower availability inside of the cardiomyocytes makes the heart contraction less intense, and this reduces the heart rate. A slower heart rate means that the heart consumes less oxygen, lowering the oxygen demand. This condition is beneficial in conditions where there is an obstruction of the blood flow leading to lower oxygen delivery, like in atherosclerosis [12].

A crucial factor in the decrease in heart workload is the decrease in blood pressure. Dilated peripheral arteries in the body decrease the force with which the heart has to pump. This allows the heart to sustain efficiency with less effort [12].

It's important to note that while Cardizem has a direct effect on the heart and arteries, it does not cure heart or circulatory diseases. Instead, it helps to manage symptoms and improve the quality of life for individuals with these conditions [12].

Side effects of Cardizem

Cardizem has a protective effect on all the organs of the body in hypertension. However, this calcium channel blocker also has several possible adverse effects. The most common side effects are:

  • headache,
  • dizziness,
  • flushing
  • constipation
  • diarrhea
  • bradycardia (slower than 60 bpm heart rate) [1].

There is also the probability of severe adverse effects like:

  • swelling of various parts of the body, like the face or tongue,
  • difficulty breathing,
  • extreme fatigue
  • fainting
  • bruising
  • change of the skin color to yellowish hue
  • flu similar symptoms [1].

In rare cases, dermatological side effects can occur, such as erythema multiforme with painful ulcerations [13].

What is Multaq?

Multaq, also known as dronedarone, is a class III antiarrhythmic drug used in atrial fibrillation (AFib). At the biochemical level, it is similar to amiodarone. Dronedarone is prescribed for persistent AFib as well as for paroxysmal AFib (episodes of AFib that stop within 7 days). Multaq comes in the form of an oral tablet, usually taken twice per day [14, 15, 16].

The drug regulates the electrical activity of the heart and helps with the maintenance of the normal rhythm. It achieves the modulation of the electric currents of the heart by inhibiting multiple ion channels in the heart.

Indications for Multaq

Multaq has two primary indications:

  • persistent atrial fibrillation,
  • history of atrial fibrillations (paroxysmal atrial fibrillation) [14].

Paroxysmal AFib is characterized by occasional episodes of fibrillation that stop within seven days. Patients with this condition can prevent any future hospitalizations with Multaq [14].

Persistent AFib lasts for more than seven days. Individuals with this type of AFib can also reduce the risk of a hospital stay when treated regularly with dronedarone [14].

Mechanism of action of Multaq

One of the key mechanisms of action of dronedarone is its ability to inhibit cardiac potassium channels (inwardly rectifying Kir2.1 channels). The drug achieves this blockage by binding to a subpart of the transporting membrane proteins. The inhibition lowers the activity of the IK1 currents, which play an important role in the electric excitation of the heart cells [17]. It could be understood that less potassium channels activity results in lower excitability of the cardiac muscle and, thus, has an antifibrillatory effect (fibrillation is promoted in cases when the tissue is easily excitable).

Dronedarone affets not only the potassium channels in the heart. Also, sodium ion channels are inhibited, what prolongs the cardiac action potential. A longer electrical signal helps with the heart rate control and stabilizes the rhythm in AFib individuals [16].

Multaq also has an antiadrenergic effect on the heart. By blocking the effects of norepinephrine and epinephrine, it can keep the heart rate low, further decreasing the probability of an AFib starting [18].

Side effects of Multaq

Like most medications, Multaq can cause a range of side effects, from mild to serious. Common side effects include:

  • diarrhea,
  • nausea,
  • vomiting,
  • skin rashes [19].

Some individuals can also have:

  • abdominal pain,
  • indigestion,
  • an allergic reaction [19].

Additionally, Multaq can also cause serious side effects like:

  • kidney problems,
  • long QT syndrome,
  • liver problems,
  • worsening or de novo heart failure.

Also, the drug increases the risk of death and stroke [19].

In rare cases, Multaq has been associated with leukocytoclastic vasculitis, a condition characterized by a rush on the legs [19].

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Jakub Gwiazdecki

Jakub Gwiazdecki

Jakub is in his fifth year as a medical student at Comenius University in Bratislava, Slovakia. He has special interested in cardiology and in patient-centered medicine. His love for heart health isn't just book-smarts; he wants to know how it works, what it means for our feelings, and how key it is for health and happiness. Jakub thinks real good health care comes from always putting the patient at the centre, treating each person as a whole.