Absorption may be impaired by antacids, minerals & multivitamins. Increased C
max of digoxin. Reduced systemic availability w/ charcoal. Increased risk of ventricular arrhythmias, including torsade de pointes in co-administration w/ anti-arrhythmics class IA (eg, quinidine, hydroquinone, disopyramide) & class III (eg, amiodarone, sotalol, dofetilide, ibutilide); antipsychotics (eg, phenothiazines, pimozide, sertindole, haloperidol, sultopride), TCAs; certain antimicrobials (eg, sparfloxacin, erythromycin IV, pentamidine, antimalarials particularly halofantrine); certain antihistamines (terfenadine, astemizole, mizalostine); cisapride, vincamine IV, bepridil, diphemanil.