Proarrhythmic effects (QTc prolongation) might occur. During first 3 months of therapy, blood dyscrasias can rarely occur. Use with caution in significant renal impairment. Pulmonary fibrosis, interstitial pneumonitis, fibrosing alveolitis, pulmonary edema, and pneumonia reported with use (fatalities occurred). Use with caution in heart failure (may precipitate or exacerbate condition). Electrolyte disturbances, especially hypokalemia or hypomagnesemia, should be corrected. Use with caution in significant hepatic impairment. Antiarrhythmic agents should be reserved for life-threatening ventricular arrhythmias.