Should be administered at least 4 hr before or 8 hr after antacids containing Al or Mg, didanosine, sucralfate & agents containing Fe or Zn. Concomitant use of drugs that induce bradycardia, hypokalemia or QT prolongation including neuroleptic, anti-infectives (eg, antimalarials, azole antimycotics, macrolides), antihistaminic (eg, terfenadine, astemizole), cisapride. Antiarrhythmic drugs class IA (eg, quinidine & procainamide) & III (eg, amiodarone & sotalol). Increased anticoagulant activity w/ concurrent use of anticoagulants. Reduced systemic availability w/ charcoal.