Hypersensitivity. Discontinue use if life-threatening shock occurs. QT interval prolongation; increased risk for ventricular arrhythmias including Torsade de pointes. Myasthenia gravis; uncorrected hypokalemia; ongoing proarrhythmic conditions eg, clinically significant bradycardia, acute myocardial ischemia. Known or suspected CNS disorders predisposing to seizures or lowered seizure threshold. Risk of developing fluoroquinolone-associated tendonitis & tendon rupture; complicated pelvic inflammatory disease. Heart & lung transplant recipients. Patients receiving class IA (eg, quinidine, procainamide) or class III (eg, amiodarone, sotalol) antiarrhythmics. Concomitant use w/ drugs prolonging QT interval eg, cisapride, erythromycin, antipsychotics, TCAs; corticosteroids. Patients on controlled Na diet. Fulminant hepatitis potentially leading to hepatic failure. Hepatic cirrhosis. Renal transplant recipients. Elderly >60 yr.