Amiodarone, a drug prescribed for heart conditions, is particularly effective at controlling rapid heart rates. While very effective, it also causes side effects in a number of organs that must be monitored by a physician. According to the U.S. Food and Drug Administration, major side effects tend to occur in the heart, liver, eyes, thyroid, and lungs. Several types of lung disease may be caused by amiodarone.
Types of Lung Disease
The incidence of amiodarone-related lung disease is estimated to be about 5 percent, according the 2010 article "Amiodarone Pulmonary Toxicity" published on the website UpToDate. Four types exist with the most common form being chronic interstitial pneumonitis, a condition that affects all of the lungs. Symptoms include the gradual onset of cough, shortness of breath and weight loss.
A second form of amiodarone lung damage is called organizing pneumonia. It comes on faster than chronic interstitial pneumonitis, and may mimic pneumonia caused by infections because of its association with fevers.
The third and most dangerous form is acute respiratory distress syndrome or ARDS, which is relatively rare. It tends to occur after major surgeries, heart surgery in particular. ARDS causes difficultly delivering oxygen to the blood and often patients require a ventilator.
The fourth type of amiodarone-related lung disease is characterized by a mass lesion in the lung which may be mistaken for an infection or cancer.
Screening and Diagnosis
According to an Archives of Internal Medicine article titled "Practical Guide for Clinicians Who Treat Patients with Amiodarone," screening is periodically undertaken to determine the presence of side effects. Screening for amiodarone-induced lung disease includes a detailed history and physical exam, yearly chest X-ray, and a measurement of gas exchange if the patient has unexplained shortness of breath or changes on X-ray. Diagnosis may also include a bronchoalveolar lavage, in which a small camera is placed down the wind pipe and cells are washed up from the lung. If that does not cinch the diagnosis, a lung biopsy may be required.
Risk Factors
An article published in the British Journal of Clinical Pharmacology in 2008 lists possible risk factors. These include a high overall dose, a daily dose of more than 400mg, preexisting lung disease, more than two months of drug therapy, old age and surgery.
Treatment
The prognosis is generally good with treatment, which primarily includes stopping the drug. For severe cases, or if the withdrawal of the drug would be too risky, steroids such as prednisone can be given.
Other Side Effects of Amiodarone
A 2007 article in the Journal of the American Medical Association notes that side effects include small deposits in the eyes in more than 90 percent of patients, damage to the eye nerves in less than 1 to 2 percent of people, gray-blue skin discoloration in 4 to 9 percent, sensitivity to the sun or light in roughly 50 percent, an underactive thyroid in 6 percent, overactive thyroid in 1 percent and minor liver issues in 15 to 30 percent. More serious liver issues are seen in less than 3 percent as well as a small number of psychiatric or nervous system problems. Lung toxicity occurs in 1 to 17 percent. Most side effects disappear after reducing the dose or stopping the medication.
References
- FDA: Amiodarone Hydrochloride Information
- JAMA: Prescribing amiodarone: an evidence-based review of clinical indications; Vassallo and Trohman; September 2007
- UpToDate: Amiodarone Pulmonary Toxicity
- Archive of Internal Medicine: Practical Guide for Clinicians
- British Journal of Clinical Pharmacology; Amiodarone-induced pulmonary toxicity; Ernawati et al; July 2008
