Amiodarone pulmonary toxicity

Overview

Amiodarone is an antiarrhythmic drug which is commonly used to treat ventricular and supraventricular arrhythmias. It is an iodine-containing compound that tends to accumulate in several organs, including the lungs. It has been associated with a variety of adverse effects. Most individuals administered amiodarone on a chronic basis will experience at least one side effect. The most serious adverse effect is amiodarone-induced pulmonary toxicity. It occurs mostly in patients receiving large doses of the drug over prolonged periods.

Amiodarone Pulmonary Toxicity

Pulmonary toxicity is the most serious adverse effect of amiodarone, which may occur in up to 5–10% of treated patients.

Types

Acute Pulmonary Toxicity

• Acute respiratory distress syndrome

Intermediate Pulmonary Toxicity

• Diffuse alveolar hemorrhage
• Pneumonia

Chronic Pulmonary Toxicity

• Chronic interstitial pneumonitis
• Solitary lung mass

Risk Factors

Anybody taking amiodarone is at risk. People on higher doses and people who have been taking the drug for a long time appear to have a higher risk, and some evidence suggests that individuals with underlying lung disease are also more likely to have problems with amiodarone.

• High cumulative dose (more than 400 milligrams per day)
• Duration over two months
• Increased age
• 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 drug 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.