A pharmacokinetic interaction between clarithromycin and sirolimus in kidney transplant recipient.

Bacterial infection is a frequent event in renal transplant recipients and often requires the use of antimicrobial agents. In this paper it is reported an evidence of pharmacokinetic interaction between clarithromycin and sirolimus in a kidney transplanted woman, suffering from pulmonary infection sustained by a bacterial pathogen, in particular Hemophilus Influenzae. In the present case report, the concomitant administration of clarithromycin and sirolimus determined impressive increase of sirolimus trough blood concentrations from 6.2 up to 54 ng/mL and this increase was associated with an acute impairment of renal function, almost completely reversed upon both drugs discontinuation. This drug-drug interaction is due to a likely inhibition of activity of both cytochrome P450 3A4 and P-glycoprotein. Although this interaction could be predicted, it represents the first reported clinical evidence.