Potentially fatal interaction between erythromycin and disopyramide

E rythromycin has been found to interact with waring disopyramide, 200 mg four times a day. His QT, farin, cyclosporine, and theophylline [l-3]. We interval measured during this period was 0.43 second describe two patients in whom we believe life-threatand his renal function was normal. Six days prior to ening complications may have resulted from a previadmission, he presented with trilobar pneumonia, and ously undescribed interaction between erythromycin erythromycin base, 500 mg four times a day, was beand the antiarrhvthmic agent disopsramide. gun. On the dav of admission, he presented with mal--