Clarithromycin markedly increases
digoxin levels, and numerous cases of
digoxin toxicity have been reported. Increases in
serum digoxin levels also occur with
telithromycin. Cases of rapid and marked two to fourfold increases in
serum digoxin levels have also been reported for
azithromycin,
erythromycin, josamycin and roxithromycin.
It is important to monitor all patients well for signs of increased
digoxin effects (see digoxin) when any macrolide is first given. Measure
digoxin levels and reduce the dosage as necessary. It has been suggested that the interaction between
digoxin and
clarithromycin may be dependent on the
clarithromycin dosage, and may be more likely in the elderly, because of a reduction in
renal function.