In vitro topotekan neinhiboval enzymy CYP1A2, CYP2A6, CYP2C8/ 9, CYP2C19, CYP2D6, CYP2E, CYP3A nebo CYP4A lidského cytochromu P450 ani lidské cytosolové enzymy dihydropyrimidin a xanthinoxidázu.
35 In-vitro werden de humane P450 enzymen CYP1A2, CYP2A6, CYP2C8/ 9, CYP2C19, CYP2D6, CYP2E, CYP3A of CYP4A evenals de humane cytosolenzymen dihydropyrimidine of xanthine oxidase niet door topotecan geremd.