Concomitant taking of P-gp inhibitors (including but not limited to ritonavir, cyclosporine A, ketoconazole, itraconazole, erythromycin, verapamil, quinidine, tacrolimus, nelfinavir, saquinavir, and amiodarone) with Afatinib can increase exposure to afatinib. Reduce Afatinib daily dose as recommended.
Concomitant taking of P-gp inducers (including but not limited to rifampicin, carbamazepine, phenytoin, phenobarbital, and St. John’s wort) with Afatinib can decrease exposure to afatinib. Increase Afatinib daily dose as recommended.
from FDA,2022.04