The risk of torsade de pointes is related to the extent of QT prolongation, concomitant administration of QT prolonging medicinal products (such as class Ia and III antiarrythmics (e. g. quinidine, amiodarone, sotalol, dofetilide), antipsychotics (e. g. thioridazine), antidepressants (e. g. amitriptyline), some macrolides (e. g. erythromycin), some antihistamines (e. g. terfenadine and astemizole), some quinolone antibiotics (e. g. sparfloxacin), and other individual drugs known to increase QT interval (e. g. cisapride)), a history of torsade de pointes, pre-existing QT interval prolongation, congestive heart failure, administration of potassium-wasting diuretics, amphotericin B or other conditions that result in hypokalemia or hypomagnesaemia.