Skønt sirolimus hæmmer det humane levermikrosomale cytokrom P450, CYP2C9, CYP2C19, CYP2D6 og CYP3A4/ 5 in vitro, forventes det aktive indholdsstof ikke at hæmme aktiviteten af disse isozymer in vivo, eftersom de sirolimus koncentrationer, som er nødvendige for hæmningen er meget højere end koncentrationerne set hos patienter, der får terapeutiske doser af Rapamune.
Although sirolimus inhibits human liver microsomal cytochrome P450 CYP2C9, CYP2C19, CYP2D6, and CYP3A4/ 5 in vitro, the active substance is not expected to inhibit the activity of these isozymes in vivo since the sirolimus concentrations necessary to produce inhibition are much higher than those observed in patients receiving therapeutic doses of Rapamune.