Drug interaction between rifampicin and sirolimus in transplant patients.

We report two cases of drug interaction between rifampicin and sirolimus in renal trans-plant patients who were diagnosed with tuberculosis after transplantation and induction of immuno-suppressive therapy with sirolimus. The dosage of sirolimus had to be increased, in one case up to six-fold and in the second case up to five-fold, to maintain serum levels after starting the rifampicin. The two patients tolerated the treatment well, with no signs of tuberculosis and good renal function.