What is/are Amiodarone?
AMIODARONE is an antiarrhythmic drug. It helps make your heart beat regularly. Because of the side effects caused by this medicine, it is only used when other medicines have not worked. It is usually used for heartbeat problems that may be life threatening. This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.
What should I tell my health care providers before I take this medicine?
They need to know if you have any of these conditions:
- liver disease
- lung disease
- other heart problems
- thyroid disease
- an unusual or allergic reaction to amiodarone, iodine, other medicines, foods, dyes, or preservatives
- pregnant or trying to get pregnant
How should I use this medicine?
Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. You can take this medicine with or without food. However, you should always take it the same way each time. Take your doses at regular intervals. Do not take your medicine more often than directed. Do not stop taking except on the advice of your doctor or health care professional.
A special MedGuide will be given to you by the pharmacist with each prescription and refill. Be sure to read this information carefully each time.
Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.
Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.
Note: This medicine is only for you. Do not share this medicine with others.
What if I miss a dose?
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
What may interact with this medicine?
Do not take this medicine with any of the following:
- arsenic trioxide
- certain macrolide antibiotics
- certain quinolone antibiotics
- medicines for malaria like chloroquine and halofantrine
- medicines for mental depression such as tricyclic antidepressants
- medicines to control heart rhythm like disopyramide, dofetilide, ibutilide, propafenone, and sotalol
- phenothiazines like chlorpromazine, mesoridazine, and thioridazine
- red yeast rice
This medicine may also interact with the following:
- beta blockers
- calcium channel blockers
- general anesthetics
- grapefruit juice
- medicines for fungal infections like ketoconazole, fluconazole, and itraconazole
- medicines for HIV, AIDS
- medicines for seizures such as phenytoin
- medicines for thyroid problems
- medicines to lower cholesterol such as atorvastatin, cerivastatin, lovastatin, or simvastatin
- rifampin, rifabutin, or rifapentine
- St. John's Wort
This list may not describe all possible interactions. Give your health care providers a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.
What side effects may I notice from this medicine?
Side effects that you should report to your doctor or health care professional as soon as possible:
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- breathing problems
- chest pain
- dark urine
- fast, irregular heartbeat
- feeling faint or light-headed
- intolerance to heat or cold
- nausea or vomiting
- pain and swelling of the scrotum
- pain, tingling, numbness in feet, hands
- spitting up blood
- stomach pain
- unusual or uncontrolled movements of body
- unusually weak or tired
- weight gain or loss
- yellowing of the eyes or skin
Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):
- blue gray coloring of the skin
- blurred vision, seeing blue green halos, increased sensitivity of the eyes to light
- change in sex drive or performance
This list may not describe all possible side effects.
What should I watch for while using this medicine?
Your condition will be monitored closely when you first begin therapy. Often, this drug is first started in a hospital or other monitored health care setting. Once you are on maintenance therapy, visit your doctor or health care professional for regular checks on your progress. Because your condition and use of this medicine carry some risk, it is a good idea to carry an identification card, necklace or bracelet with details of your condition, medications, and doctor or health care professional.
You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells.
This medicine can make you more sensitive to the sun. Keep out of the sun. If you cannot avoid being in the sun, wear protective clothing and use sunscreen. Do not use sun lamps or tanning beds/booths.
You should have regular eye exams before and during treatment. Call your doctor if you have blurred vision, see halos, or your eyes become sensitive to light. Your eyes may get dry. It may be helpful to use a lubricating eye solution or artificial tears solution.
If you are going to have surgery or a procedure that requires contrast dyes, tell your doctor or health care professional that you are taking this medicine.
Where should I keep this medicine?
Keep out of the reach of children.
Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Protect from light. Keep container tightly closed. Throw away any unused medicine after the expiration date.
Mechanism of action
Amiodarone is categorized as a class III antiarrhythmic agent, and prolongs phase 3 of the cardiac action potential, the repolarization phase where there is normally decreased calcium permeability and increased potassium permeability. It has numerous other effects however, including actions that are similar to those of antiarrhythmic classes Ia, II, and IV.
Amiodarone shows beta blocker-like and potassium channel blocker-like actions on the SA and AV nodes, increases the refractory period via sodium- and potassium-channel effects, and slows intra-cardiac conduction of the cardiac action potential, via sodium-channel effects.
Amiodarone chemically resembles thyroxine (thyroid hormone), and its binding to the nuclear thyroid receptor might contribute to some of its pharmacologic and toxic actions
Indications for use
Because amiodarone has a low incidence of pro-arrhythmic effects, it has been used both in the treatment of acute life-threatening arrhythmias as well as the chronic suppression of arrhythmias. It is useful both in supraventricular arrhythmias and ventricular arrhythmias.
Amiodarone has numerous side effects. Most individuals administered amiodarone on a chronic basis will experience at least one side effect.
A chest X-ray demonstrating pulmonary fibrosis due to amiodarone.
The most serious reaction that is due to amiodarone is interstitial lung disease. Risk factors include high cumulative dose, more than 400 milligrams per day, duration over two months, increased age, and preexisting pulmonary disease. Some individuals were noted to develop pulmonary fibrosis after a week of treatment, while others did not develop it after years of continuous use. Common practice is to avoid the agent if possible in individuals with decreased lung function.
The most specific test of pulmonary toxicity due to amiodarone is a dramatically decreased DLCO noted on pulmonary function testing.
Thyroxine and amiodarone have similar structures.
Induced abnormalities in thyroid function are common. Amiodarone is structurally similar to thyroxine (a thyroid hormone), which contributes to the effects of amiodarone on thyroid function. Both under- and overactivity of the thyroid may occur on amiodarone treatment. Measurement of free thyroxine (FT4) alone may be unreliable in detecting these problems and thyroid-stimulating hormone (TSH) should therefore also be checked every 6 months.
Hypothyroidism (slowing of the thyroid) occurs frequently; in the SAFE trial, which compared amiodarone with other medications for the treatment of atrial fibrillation, biochemical hypothyroidism (as defined by a TSH level of 4.5-10 mU/l) occurred in 25.8% of the amiodarone-treated group as opposed to 6.6% of the control group (taking placebo or sotalol). Overt hypothyroidism (defined as TSH >10 mU/l) occurred at 5.0% compared to 0.3%; most of these (>90%) were detected within the first six months of amiodarone treatment.
Hyperthyroidism (an overactive thyroid, due to the Jod-Basedow Effect) can also occur. However, in the SAFE trial, the increased rate of hyperthyroidism (5.3% compared to 2.4%) was not statistically significant. Most hyperthyroid patients (defined as TSH <0.35 mU/l) were asymptomatic.
Thyroid uptake measurements (I-123 or I-131), which are used to differentiate causes of hyperthyroidism, are generally unreliable in patients who have been taking amiodarone. Because of the high iodine content of amiodarone, the thyroid gland is effectively saturated, thus preventing further uptake of isotopes of iodine. However, the radioactive iodine uptake (nuclear thyroid uptake test) may still be helpful in the diagnosis and management of amiodarone-induced hyperthyroidism.
Corneal micro-deposits (Cornea verticillata, also called vortex or whorl keratopathy) are almost universally present (over 90%) in individuals taking amiodarone longer than 6 months, especially doses greater than 400 mg/day. These deposits typically do not cause any symptoms. About 1 in 10 individuals may complain of a bluish halo. Anterior subcapsular lens deposits are relatively common (50%) in higher doses (greater than 600 mg/day) after 6 months of treatment. Optic neuropathy, nonarteritic anterior ischemic optic neuropathy (N-AION), occurs in 1-2% of people and is not dosage dependent. Bilateral optic disc swelling and mild and reversible visual field defects can also occur.
Gastrointestinal system and liver
Abnormal liver enzyme results are common in patients on amiodarone. Much rarer are jaundice, hepatomegaly (liver enlargement), and hepatitis (inflammation of the liver).
Low-dose amiodarone has been reported to cause pseudo-alcoholic cirrhosis.
Long-term administration of amiodarone is associated with a blue-grey discoloration of the skin. This is more commonly seen in individuals with lighter skin tones. The discoloration may revert upon cessation of the drug. However, the skin color may not return completely to normal.
Individuals taking amiodarone may become more sensitive to the harmful effects of UV-A light. Using sunblock that also blocks UV-A rays appears to prevent this side effect.
Long-term administration of amiodarone has been associated with peripheral neuropathies.
Amiodarone is sometimes responsible for epididymitis, a condition of the scrotum normally associated with bacterial infections but which can also occur as a non-bacterial inflammatory condition. Amiodarone accumulates in the head of the organ and can cause unilateral or bilateral inflammation. It tends to resolve if amiodarone is stopped.
Some cases of gynecomastia have been reported with men on amiodarone.
A study published in 2013 showed an association between amiodarone and an increased risk of cancer, especially in males, with a dose-dependent effect.
This article uses material from the Wikipedia article Amiodarone , which is released under the Creative Commons Attribution-Share-Alike License 3.0.