Alectinib Posaconazole
ModeratePosaconazole is a strong CYP3A inhibitor. In a study, 400 mg of it twice daily was given with a single 300 mg dose of Alecensa (alectinib). Alectinib's peak level (Cmax) rose 1.18-fold and its total exposure (AUCinf) rose 1.75-fold. Levels of M4, its active by-product, went the other way: peak (Cmax) fell by 71% and total exposure (AUCinf) by 25%.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.