- Caution should be exercised when administering paclitaxel (Taxol) concomitantly with medicines known to inhibit (e.g. ketoconazole and other imidazole antifungals, erythromycin, fluoxetine, gemfibrozil, cimetidine, ritonavir, saquinavir, indinavir and nelfinavir) OR induce (e.g. rifampicin, carbamazepine, phenytoin, efavirenz and nevirapine) either CYP2C8 or CYP3A4. Based on the in vitro data and SimCYP simulations, selumetinib is considered unlikely to perpetrate clinically significant drug-drug interaction via inhibition or induction of CYP enzymes