Several patients have had marked increases in
serum tacrolimus levels accompanied by evidence of
renal toxicity when they also took
erythromycin. The same interaction has been seen in patients given
clarithromycin, and is predicted with josamycin.
Tacrolimus levels and/or effects (e.g. on
renal function) should be monitored as a
matter of routine, but it may be prudent to increase monitoring if these
macrolides are started or stopped. Note that the
macrolides differ in their ability to inhibit
CYP3A4, see
macrolides. Azithromycin has been predicted not to interact and in general case reports seem to confirm this, although one patient has experienced increased
tacrolimus levels when also taking
azithromycin.