Two patients had large elevations in their 
sirolimus levels following the addition of 
erythromycin. 
 This interaction is in line with the manufacturer's prediction. They also predict that other inhibitors of CYP3A4 (they name 
clarithromycin and telithromycin) will interact similarly, and should be avoided. Note that the 
macrolides differ in their ability to inhibit CYP3A4, see 
macrolides. Other 
macrolides seem less likely to interact.