Amiodarone is an anti-arrhythmic medication that is classified as a Class III agent. It has been approved for the treatment of life-threatening arrhythmias that are resistant to first-line therapy. It is a powerful medication that works when other anti-arrhythmic medications fail; however, it has a wide range of adverse effects and complications that the patient must consider before agreeing to therapy.
Pulmonary Problems
Complications with the lungs, or pulmonary system, can be quite severe with amiodarone therapy. Patients often initially complain of cough, fever, wheezing, coughing up blood, or progressive dyspnea (difficulty breathing). These can be harbingers of complications such as pulmonary fibrosis, hypersensitivity pneumonitis or interstitial pneumonitis. The hypersensitivity pneumonitis is unique in that it can be treated with corticosteroids and cessation of the medication.
Gastrointestinal Disturbances
Problems with the gastrointestinal system can occur in patients on amiodarone. They include nausea, vomiting, constipation, and abdominal discomfort. They do not necessitate cessation of therapy and can be alleviated with decreased amiodarone dosage.
Toxicity to the liver can occur and can be fatal, however, and is manifested by weight loss, swelling of the liver, abdominal fluid buildup and right upper quadrant abdominal pain. In this case, the dosage should be reduced if not stopped.
Blood Abnormalities
Amiodarone therapy can be a cause of problems with cells found in blood. Anemia, decreased white cell count, and decreased platelet count are all possible.
Cardiovascular Complications
Often the biggest side effect of an anti-arrhythmic drug is disruptions with normal cardiac rhythm; this can make a complication difficult to distinguish from normal medication function. Patients have reported decreased heart rate (known as bradycardia), congestive heart failure, decreased blood pressure (hypotension), cardiac arrest and possible cardiovascular collapse. Supportive therapy such as intravenous fluids and cessation of therapy is usually necessary with complications involving the cardiovascular system.
Neurologic System Toxicity
The nervous system can also suffer complications during amiodarone therapy. Symptoms include tremor, ataxia (problems with coordination), dizziness, tingling, numbness, weakness and headaches. Therapy likely will need to be reduced to alleviate symptoms.
Endocrine Complications
The thyroid hormone is one of the principal sites of amiodarone complications. It can cause both increased (hyperthyroid) or decreased (hypothyroid) thyroid function and occurs in 2 to 10 percent of users. Symptoms can include problems with heart rate, skin manifestations (dry, mottled skin), fatigue, weight gain/loss, diarrhea, constipation and temperature intolerance among others depending on the exact effect on the thyroid. The dosage is often lowered, but often cessation of treatment is warranted. In addition, amiodarone has been associated with sexual dysfunction such as impotence and decreased libido.
Skin Complications
Numerous dermatologic problems can occur with amiodarone therapy. Examples include sensitivity to light (photosensitivity), blue-gray skin discoloration, skin cancer, itching and rash. These effects may reverse slowly with drug cessation but often resolve incompletely.
Visual Disturbances
Problems with the visual system in those undergoing amiodarone therapy include blurry vision, lens opacities, dry eyes, halos around objects and sensitivity to light. Often they occur when the length of therapy exceeds six months and in some cases have led to permanent blindness.
References
- Cordarone (amiodarone) package insert. Philadelphia, PA: Wyeth Laboratories; 2007 Mar
- "Annals of Internal Medicine;" Amiodarone: reevaluation of an old drug; Harjai, KJ et al. Volume 126, 1997
- "American Heart Journal;" A randomized comparison of amiodarone and class IC antiarrhythmic drugs to treat atrial fibrillation in patients paced for sinus node disease: The Prevention Investigation and Treatment: A Group for Observation and Research on Atrial arrhythmias ; Gulizia, M et al. Volume 155, January 2008
