Review Question - QID 212795

This patient with dry cough, shortness of breath, and abdominal pain after starting an antiarrhythmic drug is most likely experiencing side effects from amiodarone, which works as a potassium channel blocker.

Amiodarone is a class III antiarrhythmic drug that works by blocking potassium channels. It has a wide variety of side effects so it is important to monitor patients who are started on this drug by checking pulmonary function tests, liver function tests, and thyroid function tests. These side effects include pulmonary fibrosis, hepatotoxicity, thyrotoxicity, blue/gray skin deposits, photodermatitis, corneal deposits, neurologic effects, gastrointestinal effects, cardiovascular depression, bradycardia, heart block, and heart failure. Despite these side effects, amiodarone can be effective in the treatment of persistent ventricular tachycardia.

Incorrect Answers:
Answer 1: Beta-adrenergic blockers (class II) such as metoprolol can cause exacerbation of existing lung disease; however, this patient has never experienced these symptoms before and thus this is most likely the development of new lung pathology.

Answer 2: Calcium channel blockers (class IV) such as verapamil can cause constipation and flushing but would not result in pulmonary symptoms.

Answer 4: Sodium channel blockers with a prolonged refractory period (class IA) such as procainamide can cause thrombocytopenia, headache, and tinnitus; however, they would not result in pulmonary symptoms.

Answer 5: Sodium channel blockers with a shortened refractory period (class IB and IC) such as flecainide can cause central nervous system effects and cardiovascular depression; however, they would not result in pulmonary symptoms.

Bullet Summary:
Amiodarone is a potassium channel blocker antiarrhythmic that is associated with the side effects of pulmonary fibrosis and liver toxicity.