The SPC has been updated with the following information: Docetaxel should be administered with caution in patients concomitantly receiving potent CYP3A4 inhibitors (e.g. protease inhibitors like ritonavir, azole antifungals like ketoconazole or itraconazole). A drug interaction study performed in patients receiving ketoconazole and docetaxel showed that the clearance of docetaxel was reduced by half by ketoconazole, probably because the metabolism of docetaxel involves CYP3A4 as a major (single) metabolic pathway. Reduced tolerance of docetaxel may occur, even at lower doses.