. other drugs: astemizole, erythromycin, quinine, chloroquine, halofantrine, pentamidine, probucol, terfenadine, vincamine, some tricyclic antidepressants, some neuroleptics (e. g. sultopride, phenothiazines): risk of torsades de pointes due to prolongation of the Q-Tc interval (additive electrophysiologic effects).