Amiodarone: an antiarrhythmic medication

Amiodarone: Most Effective and Most Toxic

By Steve S. Ryan, PhD

Amiodarone (Cordarone) is considered one of the most effective antiarrhythmic drugs, but it’s also one of the most toxic. It may affect your lungs, eyes, thyroid, liver, skin, heart, and nervous system. Also, amiodarone has a long half-life. It is retained in the body for up to 45 days after the drug has been discontinued. Many Electrophysiologists (EPs) considered it a drug of last resort or a drug that should only be used for a short time. (Cardiologists in general prescribe amiodarone more readily than EPs.)

Be advised: A newer drug, dronedarone (brand name Multaq), is now on the market and may be a substitute for amiodarone. Dronedarone may not be quite as effective as amiodarone, but is considered safer. However, some studies indicate that donedarone (Multaq) may have problems. 

Monitor and Test Frequently

If you are taking amiodarone, you should be monitored and tested frequently and scrupulously for damage to your organ systems (your doctor may already be doing this). You should keep copies of any tests. What’s important is not so much whether you are within a “normal” range, but whether your measurements are going up and how fast.

Note: it’s important that baseline values for organ systems should be documented before you start taking Amiodarone.

Contact your doctor immediately if, after taking amiodarone, you experience any new symptoms such as: coughing, wheezing, shortness of breath, visual changes, skin rash, pain, tingling or weakness in the arms or legs, fever, rapid heart beat, fatigue, lethargy, unusual weight gain, swelling, hair loss, cold or heat intolerance, lightheadedness or fainting.

The recommended maintenance dose of amiodarone is 200 mg/day. A possible toxic level of amiodarone may be 400 mg daily for more than two months, or a low dose for more than two years.

Susan Grider, of AmiodaroneToxicity: The Drug Amiodarone Is a Deadly Killer, emailed me this observation:

“While you do point out that amiodarone is dangerous, you’re not nearly emphatic enough about it. A patient could easily justify taking amiodarone after reading your description calculating that when symptoms present themselves, they will simply stop treatment. It’s not that easy as some have suffered permanently as a result of only one dose. In addition, the symptoms of amiodarone toxicity are not always recognized (even by the medical community) before it is too late. Amiodarone is a drug of last resort and that’s according to the FDA. Patients who take this drug should have exhausted every other treatment possibility.” See also the website: AmiodaroneToxicity: The Drug Amiodarone Is a Deadly Killer.

Damage and Toxicity to Organ Systems

LUNGS: Perhaps the most important test is for the lungs. “Amiodarone-induced pulmonary toxicity can be progressive and fatal if not recognized and treated.” You should have a chest X-Ray and Pulmonary function testing with diffusion capacity (DLCO) before starting and at least every year you are on amiodarone.

THYROID: Thyroid problems from amiodarone are all too common and can occur in as many as 22% of patients. Decreased energy, cold intolerance and weight gain are among the most common effects of decreased thyroid function. You should test for blood levels of TSH (Thyroid Stimulating Hormone), as well as the thyroid hormones free T4 and total T3. Amiodarone can also increase thyroid function with symptoms such as atrial rhythm disturbances, elevated heart rate, heat intolerance, and weight loss.

EYES: Corneal microdeposits occur in the majority of patients who take amiodarone, but they usually don’t cause any ill effects. More substantial microdeposits, however, can cause visual disturbances and even severe damage/inflammation of the optic nerve which can cause blindness. On taking amiodarone, you should have yearly eye exams. Report any visual changes immediately to your Electrophysiologist.

LIVER: Amiodarone commonly causes liver toxicity, but usually only mild increases in blood liver function tests (LFTs). The liver function tests are AST (SGOT), ALT (SGPT), and bilirubin. More severe cases can result in liver failure signaled by jaundice, abdominal pain, and distension.

SKIN: Amiodarone increases sensitivity to the sun and sun burning. This increased sensitivity to the sun can be severe in approximately 10% of patients. Avoid the sun, apply sunscreen, and wear additional clothing.
It also can produce a blue or gray discoloration of the skin if one takes heavy doses and/or for long periods. This discoloration can persist after stopping amiodarone, but may fade very gradually (often years) after drug discontinuation.

Nick Wander writes that after his ablation, he was put on amiodarone 400 mg/day for a month, then 200 mg/day for another month. This was to keep his heart in sync while it was healing. But after just 5 days on amio, he developed a bad rash on his upper body and had to go to the ER. They gave him steroids and Benadryl in an IV to no effect. An EpiPen (Epinephrene) helped. He was on steroids for 3 days. (Ndwander(at)gmail.com.)

HEART: Amiodarone can cause slow heart rhythm disorders such as slowing of the sinus rate and AV block. You may feel fatigued, lethargic, have poor exercise tolerance, and may experience dizziness and fainting. Less commonly, amiodarone may induce ventricular arrhythmias such as polymorphic ventricular tachycardias called “Torsades de Pointes” or TdP which can cause death.

You should have a 12 lead EKG before starting amiodarone and at six-month intervals in order to assess baseline heart rate, rhythm, and EKG signal intervals (PR, QRS, QTc). 

NEUROPATHY (weakness, numbness and pain from nerve damage): “Up to 10% of patients who take Cordarone over a period of years will develop neuropathy…and some will develop optic neuropathy, which can cause blurred vision, abnormalities in the visual field (such as “halo vision”) or even progressive (and painless) vision loss.”¹ Vision changes can occur in as little as six months. Tell your doctor right away if you notice any vision changes.

FETUS/NURSING INFANT: Amiodarone is known to cross the placenta and enter the fetus, and is excreted in breast milk. Use of amiodarone should be avoided if at all possible in women who are pregnant or likely to become pregnant. Lactating women who are taking amiodarone should not breastfeed. Due to the likelihood of toxicity if amiodarone is taken for decades, amiodarone use is strongly discouraged in children, unless there are no acceptable alternatives.

Keep in Mind

Amiodarone is a drug of last resort and that’s according to the FDA which has not approved it for A-Fib. Patients who take this drug should have exhausted every other treatment possibility. See also the website: AmiodaroneToxicity: The Drug Amiodarone Is a Deadly Killer.