Case reports suggest that
erythromycin increases
disopyramide levels, and this has resulted in QT prolongation, cardiac arrhythmias and heart block. Similar effects have been seen when
clarithromycin or
azithromycin are given with
disopyramide. Josamycin and
telithromycin are expected to interact similarly. See also drugs that prolong the QT interval.
Some of the manufacturers of
disopyramide recommend avoiding the combin- ation of
disopyramide and
macrolides that inhibit CYP3A, and this would certainly be prudent in situations where close monitoring is not possible.