Sirolimus and everolimus intestinal absorption and interaction with calcineurin inhibitors: a differential effect between cyclosporine and tacrolimus.

The mTOR inhibitors (ImTORs) sirolimus (SRL) and everolimus (EVR) have been increasingly used in renal transplantation as part of calcineurin inhibitor (CNI) sparing or avoidance regimens. Those drugs have low and variable oral bioavailability that is increased when combined with cyclosporine or tacrolimus (TAC). We investigated the mechanisms involved in ImTORs intestinal absorption in vitro and associated it with their drug-drug interactions with CNIs.