- Patients taking any medication known to increase the QT interval, eg, amiodarone, astemizole, bepridil, chloroquine, chlorpromazine, cisapride, disopyuramide, dofetilide, droperidol, halofantrine, haloperidol, ibutilide, levomethadyl, mesoradazine, methadone, pimozide, procainamide, quinidine, sotalol, terfenadine