APREPITANT AND CARBAMAZEPINE

Rifampicin, a potent inducer of CYP3A4, reduces the AUC of aprepitant by 91%; reduced efficacy would be expected. Carbamazepine, another potent inducer of CYP3A4, is predicted to interact similarly, both with aprepitant, and its prodrug fosaprepitant.
The UK manufacturer recommends that concurrent use should be avoided.