Unusual properties and side effects of amiodarone


Amiodarone (cordarone, paceron) is an effective and frequently prescribed antiarrhythmic agent, but it has some notable differences from many other drugs. If your doctor prescribes this drug for cardiac arrhythmias , you need to understand the idiosyncrasy and risks associated with it.

José Luis Peláez Inc. / Fake images

Unusual features

Amiodarone has a number of characteristics that make it unique among antiarrhythmic drugs and even drugs in general.

Long charging times

When taken by mouth, it takes several weeks for amiodarone to reach maximum effectiveness for a very unusual reason. Although most drugs circulate in the bloodstream for some time until they are metabolized or excreted from the body, amiodarone is stored in body tissues.

The full antiarrhythmic effects of the drug are not achieved until the tissues are sufficiently saturated with amiodarone. Therefore, a drug must be "loaded" before it can be optimally effective.

A typical amiodarone loading regimen is to use large oral doses for a week or two, followed by a gradual reduction in dose over the next month or so. It is not uncommon for people to first administer 800 or 1,200 milligrams (mg) per day and then finally keep it to just 100 or 200 mg per day (orally).

Amiodarone can also be given intravenously (with a much faster effect) when the treatment of an arrhythmia is urgent. However, the transition from intravenous to oral dosing should be done with caution, as the drug still needs to be loaded over a long period of time with continued use.

Long half life

Amiodarone leaves the body very, very slowly. It is not significantly excreted by the liver or kidneys. (Amiodarone is metabolized in the liver to desethylamiodarone, which has the same antiarrhythmic and toxic effects as amiodarone and which also remains in the body for a long time.)

For the most part, amiodarone and its metabolites are removed from the body when cells containing amiodarone are lost. These include, for example, cells from the skin or cells from the gastrointestinal tract, which are secreted by the millions every day. This is a long and slow process.

Therefore, even if it is determined that amiodarone should be stopped (for example, due to side effects), the drug remains in the body in measurable amounts for a long time after the last dose.

The half-life of amiodarone, unlike most other drugs, is measured in weeks, not hours .

Various mechanisms

Amiodarone works through many different mechanisms, unlike most medications. It is a class I and class III antiarrhythmic drug, it also acts as a beta- blocker and calcium blocker (class II and IV).

It dilates the blood vessels and often interferes with the action of the thyroid hormone.

All of these effects contribute to its ability to treat arrhythmias and probably explain the unique efficacy of amiodarone.

Side effects

Because amiodarone is stored in many different tissues in the body, it can cause side effects that affect many organs. Some of these side effects can take months or years to develop, so anyone taking this drug should always be vigilant.

Also, side effects of amiodarone are very rare with antiarrhythmic drugs or any other drug.

For these reasons, when amiodarone first entered clinical practice, it took health professionals more than a decade to realize that many of the strange symptoms they were seeing were caused by amiodarone.

To this day, healthcare professionals must closely monitor patients taking amiodarone at all times while taking the drug to determine if the drug is causing problems.

Some of the more common side effects that can be seen with amiodarone are:

  • Deposits on the cornea : Amiodarone usually causes deposits on the cornea of the eyes, which sometimes results in "halogen vision" when looking at a bright light at night is like looking at the moon on a foggy night.
  • Skin Discoloration: Amiodarone can cause a disfiguring (and possibly irreversible) blue-gray discoloration of the skin, usually in areas exposed to the sun.
  • Sun Sensitivity: Amiodarone often increases the skin's sensitivity to sunlight to the point that even minor exposure can cause sunburn.
  • Thyroid problems: Amiodarone can cause thyroid disorders, both hypothyroidism (low thyroid levels) and hyperthyroidism (high thyroid levels). These thyroid problems are quite common with amiodarone and can be serious. For this reason, thyroid function should be monitored regularly in patients taking this drug.
  • Liver Toxicity: Since amiodarone can cause liver toxicity , liver enzymes should be monitored regularly .
  • Upset stomach: Amiodarone often causes nausea, vomiting, or loss of appetite.
  • Pulmonary Toxicity: The most dangerous side effect of amiodarone, pulmonary toxicity , can take several forms. This can cause an acute pulmonary syndrome, from which patients become seriously ill, requires intensive care, and often leads to death. Or it can cause a more insidious, gradual, and subtle increase in lung stiffness that both the doctor and the patient may not notice until severe, probably irreversible, lung damage has occurred.

When should you use amiodarone?

Due to the unique risks and difficulties associated with the use of amiodarone, this drug should only be used in people whose arrhythmias are life-threatening or very life-threatening, and only when no other reasonable treatment is available.

Despite its shortcomings, amiodarone is in fact exceptionally effective and has helped thousands of people with disabling arrhythmias return to near-normal lives.

Get the word of drug information

When used correctly, amiodarone can be of great benefit to people with severe cardiac arrhythmias. But due to its potential toxicity, its use should be limited.

It is the responsibility of healthcare providers who prescribe amiodarone to carefully discuss with their patients the many potential problems that can arise with this drug. Physicians must commit to becoming long-term partners with their patients by carefully monitoring new side effects while using this unique drug.

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