Pacerone and Pulmonary dysfunction

Pulmonary toxicities such as hypersensitivity pneumonitis or interstitial/alveolar pneumonitis are potentially fatal (approximately 10% of the time) and have occurred in as many as 10% to 17% of patients administered daily dosages of approximately 400 mg of amiodarone. More frequently, asymptomatic abnormal diffusion capacity has been observed. Patients with preexisting pulmonary dysfunction does not appear to have an increased risk of pulmonary toxicity; however, they have a poorer prognosis if toxicity does develop. Thus, the risks and benefits of amiodarone therapy should be weighed carefully. Clinical monitoring of pulmonary function, including chest X-ray (baseline and every 3 to 6 months) and pulmonary function tests (with diffusion capacity), is recommended in all patients receiving amiodarone therapy. Any new respiratory symptom during treatment should be evaluated promptly and thoroughly, since toxicity is more likely to be reversible if diagnosed and managed early. Patients who develop hypersensitivity pneumonitis should be withdrawn permanently from amiodarone therapy and treated with steroids. In the case of interstitial/alveolar pneumonitis, steroid therapy and dosage reduction or discontinuation of amiodarone, if possible, usually result in clinical improvement. Subsequent rechallenge with amiodarone at reduced dosages does not always lead to return of toxicity and may be considered in some patients. The use of a lower loading dose and maintenance doses may also decrease the incidence of amiodarone- induced pulmonary toxicity.